Virtual synchronous control method and apparatus for energy storage system, device, and storage medium

Abstract

The present application relates to a virtual synchronous control method and apparatus for an energy storage system, a device, and a storage medium. The method comprises: controlling an output voltage of a direct-current energy storage valve on the basis of an output electrical signal measurement value of a direct-current side of a voltage source converter and an output voltage reference value of the direct-current energy storage valve; further, controlling an output signal of an alternating-current side of the voltage source converter on the basis of a grid connection point electrical signal measurement value and a grid connection point electrical signal reference value of the voltage source converter. It can thus be seen that the embodiments of the present application implement a virtual synchronous control method independently controlling a voltage source converter and a direct-current energy storage valve in an energy storage system, so that the method can be applied to virtual synchronous control of a high-voltage direct-current direct-mounted energy storage system. In addition, by means of independently controlling the voltage source converter and the direct-current energy storage valve in the energy storage system, the voltage source converter does not need to be configured to take into account both direct-current side control and alternating-current side control, so that the complexity of a control loop of the voltage source converter can be simplified.

Description

Virtual synchronization control method, device, equipment and storage medium for energy storage system Cross-references

[0001] This application refers to Chinese patent application No. 2023116087625, entitled “Virtual Synchronous Control Method, Device, Equipment and Storage Medium for Energy Storage System” filed on November 28, 2023, which is incorporated into this application in its entirety by reference. Technical Field

[0002] The present application relates to the field of energy storage technology, and in particular to a virtual synchronization control method, apparatus, device, and storage medium for an energy storage system. Background Art

[0003] With the rapid development of new power systems based on renewable energy, energy storage systems with high voltage, large capacity, and grid-friendly connectivity are becoming a new development demand and trend. Among them, high-voltage direct current (HVDC) energy storage systems have become a relatively important development direction.

[0004] In related technologies, HVDC direct-mounted energy storage systems integrate voltage source converters (VSCs) and DC energy storage valves, offering advantages such as a high degree of modularity. However, compared to traditional energy storage systems, HVDC direct-mounted energy storage systems differ in topology and functionality. Therefore, implementing virtual synchronous control of HVDC direct-mounted energy storage systems is an urgent issue. Summary of the Invention

[0005] In view of the above problems, the present application provides a virtual synchronous control method, device, equipment and storage medium for an energy storage system, which can solve the problem of virtual synchronous control of a high-voltage direct current energy storage system in the related art.

[0006] In a first aspect, the present application provides a virtual synchronization control method for an energy storage system, wherein the energy storage system includes a voltage source converter valve and a DC energy storage valve, and the method includes:

[0007] Controlling the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve;

[0008] According to the measured value of the grid-connected point electrical signal of the voltage source converter valve and the reference value of the grid-connected point electrical signal, the output signal of the AC side of the voltage source converter valve is controlled.

[0009] In the technical solution of the embodiment of the present application, the output voltage of the DC energy storage valve can be independently controlled according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve, and the output signal of the AC side of the voltage source converter valve can be independently controlled according to the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve. It can be seen that the embodiment of the present application realizes a virtual synchronous control method for independently controlling the voltage source converter valve and the DC energy storage valve in the energy storage system, so that it can be applied to the virtual synchronous control of the high-voltage direct current energy storage system, so as to realize the grid-type control of the high-voltage direct current energy storage system, which is beneficial to improving the low-voltage fault ride-through capability of the energy storage system. In addition, by independently controlling the voltage source converter valve and the DC energy storage valve in the energy storage system, the voltage source converter valve does not need to take into account both the DC side control and the AC side control, thereby simplifying the complexity of the control loop of the voltage source converter valve.

[0010] In some embodiments, the grid connection point electrical signal measurement value includes: a grid connection point active power measurement value, a grid connection point reactive power measurement value, and a grid connection point voltage measurement value; the grid connection point electrical signal reference value includes: a grid connection point active power reference value, a grid connection point reactive power reference value, and a grid connection point voltage reference value; and controlling the output signal of the AC side of the voltage source converter valve according to the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve includes:

[0011] Control the output frequency of the AC side of the voltage source converter valve according to the active power measurement value and the active power reference value of the grid connection point;

[0012] The output voltage amplitude of the AC side of the voltage source converter valve is controlled according to the reactive power measurement value of the grid connection point, the voltage measurement value of the grid connection point, the reactive power reference value of the grid connection point and the voltage reference value of the grid connection point.

[0013] In the technical solution of the embodiment of the present application, active power-frequency control of the voltage source converter valve is achieved based on the active power measurement value of the grid connection point and the active power reference value of the grid connection point, and reactive power-voltage control of the voltage source converter valve is achieved based on the reactive power measurement value of the grid connection point, the voltage measurement value of the grid connection point, the reactive power reference value of the grid connection point and the voltage reference value of the grid connection point, thereby achieving virtual synchronous control of the active power and reactive power decoupling of the voltage source converter valve, which is beneficial to the transient support of the grid connection point frequency and the grid connection point voltage, thereby further improving the low-voltage fault ride-through capability of the energy storage system.

[0014] In some embodiments, controlling the output frequency of the AC side of the voltage source converter valve according to the grid connection point active power measurement value and the grid connection point active power reference value includes:

[0015] Determine the active power deviation of the grid connection point based on the active power measurement value of the grid connection point and the active power reference value of the grid connection point;

[0016] Performing a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result;

[0017] The output frequency is controlled according to the closed-loop result and the rated angular frequency of the power grid.

[0018] In the technical solution of the embodiment of the present application, by converting the active power deviation of the grid connection point into the output frequency of the AC side of the voltage source converter valve, it is beneficial to adjust the active power of the grid connection point to the active power reference value of the grid connection point.

[0019] In some embodiments, determining the active power deviation of the grid connection point according to the measured active power value of the grid connection point and the active power reference value of the grid connection point includes:

[0020] The active power reference value of the grid connection point is limited according to the maximum active power limit value and the minimum active power limit value to obtain the active power reference value of the grid connection point after limiting;

[0021] The active power deviation of the grid connection point is obtained by subtracting the active power reference value of the grid connection point after limiting from the active power measurement value of the grid connection point.

[0022] In the technical solution of the embodiment of the present application, by limiting the grid-connected point active power reference value, the grid-connected point active power reference value after limiting can be made consistent with the actual capacity of the energy storage system, so that a more accurate grid-connected point active power deviation can be obtained based on the grid-connected point active power reference value after limiting and the grid-connected point active power measurement value, which is conducive to more accurately controlling the output frequency of the AC side of the voltage source converter valve based on the grid-connected point active power deviation.

[0023] In some embodiments, performing a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result includes:

[0024] Determining a first feedback signal based on historical closed-loop results and a damping coefficient;

[0025] A first integration process is performed on a difference signal between the active power deviation of the grid connection point and the first feedback signal to obtain a closed-loop result.

[0026] In some embodiments, performing a first integration process on a difference signal between the active power deviation of the grid connection point and the first feedback signal to obtain a closed-loop result includes:

[0027] A first integration process is performed on the difference signal according to the inertia time constant and the latch coefficient to obtain a closed-loop result.

[0028] In some embodiments, the method further comprises:

[0029] The maximum active power limit and the minimum active power limit are adjusted according to the grid connection point fault detection signal so that the active power reference value of the energy storage system does not exceed the actual capacity of the system during the fault, thereby improving the transient stability of the energy storage system during the fault.

[0030] In some embodiments, adjusting the maximum active power limit value and the minimum active power limit value according to the grid connection point fault detection signal includes:

[0031] When a grid connection point fault detection signal is detected indicating that a fault has occurred in the energy storage system, the maximum active power limit value is adjusted to the target maximum power limit value, and the minimum active power limit value is adjusted to the target minimum power limit value; or

[0032] When a grid connection point fault detection signal is detected to indicate that the fault is cleared within a first preset time period, the maximum active power limit value is adjusted from the target power maximum limit value to the preset power maximum limit value, and the minimum active power limit value is adjusted from the target power minimum limit value to the preset power minimum limit value.

[0033] In some embodiments, the target power maximum limit value and the target power minimum limit value are both related to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, and the drop amplitude of the grid connection point voltage measurement value during the fault period.

[0034] In the technical solution of the embodiment of the present application, by adjusting the target power maximum limit value and the target power minimum limit value according to the reactive power measurement value of the grid connection point, the voltage measurement value of the grid connection point and the drop amplitude of the grid connection point voltage measurement value during the fault period, the active power reference value of the energy storage system during the fault period can be made not to exceed the actual capacity of the system, thereby alleviating the problem that the active power input is always greater than zero, causing the angle to increase continuously, and ultimately leading to periodic changes in the grid connection point voltage and large swings in the active power, thereby improving the transient stability of the energy storage system during the fault period.

[0035] In some embodiments, the method further comprises:

[0036] The damping coefficient and latching coefficient are adjusted according to the grid connection point fault detection signal so that the active power reference value of the energy storage system does not exceed the actual capacity of the system during the fault, thereby improving the transient stability of the energy storage system during the fault.

[0037] In some embodiments, adjusting the damping coefficient and the latching coefficient according to the grid connection point fault detection signal includes:

[0038] When a grid connection point fault detection signal is detected indicating that a fault has occurred in the energy storage system, the damping coefficient is adjusted to a target damping coefficient, and the latching coefficient is adjusted to a target latching coefficient; or

[0039] When it is detected that the grid connection point fault detection signal indicates that the fault is cleared within the second preset time period, the damping coefficient is adjusted from the target damping coefficient to the preset damping coefficient, and the latching coefficient is adjusted from the target latching coefficient to the preset latching coefficient.

[0040] In the technical solution of the embodiment of the present application, by adaptively adjusting the damping coefficient and the latching coefficient to adjust the integral link of the active frequency, the power angle movement during the fault period can be further reduced, so that the absolute value of the active power deviation is as small as possible, thereby alleviating the problem of large power angle swing after fault recovery and continuous periodic fluctuation of the grid connection point voltage, thereby improving the transient stability of the energy storage system during the fault recovery process.

[0041] In some embodiments, the target latching coefficient is zero, and the target damping coefficient is related to the offset of the active power of the grid connection point during the fault period and the allowable frequency offset during the fault period.

[0042] In some embodiments, the method further comprises:

[0043] A grid connection point fault detection signal is determined based on the grid connection point voltage measurement value, a preset fault detection threshold, and a preset fault clearing threshold.

[0044] In the technical solution of the embodiment of the present application, a grid connection point fault detection signal is determined based on the grid connection point voltage measurement value, the preset fault detection threshold and the preset fault clearing threshold, so that the active power limit value, the damping coefficient and the latching coefficient can be adjusted according to the grid connection point fault detection signal, so that the active power reference value of the energy storage system during the fault period does not exceed the actual capacity of the system, thereby improving the transient stability of the energy storage system during the fault period.

[0045] In some embodiments, determining a grid connection point fault detection signal based on a grid connection point voltage measurement value, a preset fault detection threshold, and a preset fault clearing threshold includes:

[0046] Upon detecting that a change in the grid connection point voltage measurement value is less than 0, and the grid connection point voltage measurement value is less than or equal to a preset fault detection threshold value within a third preset time period, determining that a grid connection point fault detection signal is used to indicate that a fault has occurred in the energy storage system, and recording a drop in the grid connection point voltage measurement value during the fault period;

[0047] When it is detected that the change value of the grid connection point voltage measurement value is greater than 0, and the grid connection point voltage measurement value is greater than or equal to the preset fault clearing threshold, it is determined that the grid connection point fault detection signal is used to indicate that the energy storage system fault is cleared within a fourth preset time period, and the drop amplitude of the grid connection point voltage measurement value during the fault period is adjusted to the preset drop amplitude.

[0048] In some embodiments, controlling the output voltage amplitude of the AC side of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value, and the grid connection point voltage reference value includes:

[0049] Determining a first internal potential amplitude of the voltage source converter valve according to a measured value of reactive power at the grid connection point, a measured value of voltage at the grid connection point, a reference value of reactive power at the grid connection point, and a reference value of voltage at the grid connection point;

[0050] According to the first internal potential amplitude of the voltage source converter valve, the output voltage amplitude of the AC side of the voltage source converter valve is controlled.

[0051] In the technical solution of the embodiment of the present application, reactive power-voltage control of the voltage source converter valve is achieved by determining the first internal potential amplitude of the voltage source converter valve and controlling the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude, which is conducive to adjusting the grid connection point voltage to the grid connection point voltage reference value.

[0052] In some embodiments, determining a first internal potential amplitude of the voltage source converter valve according to a grid connection point reactive power measurement value, a grid connection point voltage measurement value, a grid connection point reactive power reference value, and a grid connection point voltage reference value includes:

[0053] Determine the reactive power deviation of the grid connection point based on the reactive power measurement value of the grid connection point and the reactive power reference value of the grid connection point;

[0054] Determine the grid connection point voltage deviation based on the grid connection point voltage measurement value and the grid connection point voltage reference value;

[0055] A second integration process is performed based on the reactive power deviation at the grid connection point and / or the voltage deviation at the grid connection point to obtain a first internal potential amplitude.

[0056] In some embodiments, controlling the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude of the voltage source converter valve includes:

[0057] Performing voltage outer loop control processing according to the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop;

[0058] Perform current limiting inner loop processing according to the current command value to obtain the output voltage signal of the AC side of the voltage source converter valve;

[0059] According to the output voltage signal of the AC side of the voltage source converter valve, the output voltage amplitude of the AC side of the voltage source converter valve is controlled.

[0060] In some embodiments, performing voltage outer loop control processing based on the first inner potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop includes:

[0061] A first PI adjustment process, a dynamic virtual impedance process or a static virtual impedance process is performed on the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop.

[0062] In some embodiments, the method further comprises:

[0063] When it is detected that the energy storage system is in the initial stage of grid connection, the output signal of the AC side of the voltage source converter valve is pre-synchronized according to the measured value of the grid connection point voltage. This ensures that the internal potential amplitude and output phase angle (or vector angle) of the voltage source converter valve can be kept the same as the amplitude and vector angle of the grid connection point voltage, respectively. This can minimize the current impact at the moment of grid connection, thereby facilitating smooth switching.

[0064] In some embodiments, the grid connection point voltage measurement value includes a first axis voltage measurement component and a second axis voltage measurement component, and pre-synchronization processing is performed on the output signal of the AC side of the voltage source converter valve according to the grid connection point voltage measurement value, including:

[0065] Performing a second PI adjustment process on the first axis voltage measurement component to obtain an adjusted first axis voltage measurement component;

[0066] Performing a second integration process on the adjusted first axis voltage measurement component and the grid rated angular frequency to obtain an output voltage phase angle on the AC side of the voltage source converter valve; wherein the output voltage phase angle is the same as the grid connection point voltage phase angle;

[0067] A second closed-loop processing is performed on the second axis voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve; wherein the second internal potential amplitude is the same as the grid connection point voltage amplitude.

[0068] In the technical solution of the embodiment of the present application, by performing PI adjustment processing and integration processing on the first-axis voltage measurement component and performing a second closed-loop processing on the second-axis voltage measurement component, the internal potential amplitude and output voltage phase angle of the voltage source converter valve synchronized with the grid connection point voltage can be generated, so as to minimize the current impact at the grid connection moment, thereby facilitating smooth switching.

[0069] In some embodiments, performing a second closed-loop processing on the second axis voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve includes:

[0070] determining a second feedback signal according to the historical internal potential amplitude;

[0071] The difference signal between the second axis voltage measurement component and the second feedback signal is sequentially subjected to a third PI adjustment process and a third integration process to obtain a second internal potential amplitude.

[0072] In some embodiments, the output electrical signal measurement value includes: an output voltage measurement value of the DC side of the voltage source converter valve and an output current measurement value of the DC side of the voltage source converter valve. Controlling the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve includes:

[0073] Performing a fourth PI adjustment process on a DC voltage difference between a measured output voltage value of the DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve to obtain a DC current command value;

[0074] Performing a fifth PI adjustment process on the DC current difference between the output current measurement value of the DC side of the voltage source converter valve and the DC current command value to obtain an output voltage command value of the DC energy storage valve;

[0075] The output voltage of the DC energy storage valve is controlled according to the output voltage command value of the DC energy storage valve.

[0076] In the technical solution of the embodiment of the present application, independent control of the output voltage of the DC energy storage valve is achieved based on the output voltage measurement value and output current measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve. This allows the voltage source converter valve to be free from the need to consider both DC side control and AC side control. On the one hand, this simplifies the complexity of the control loop of the voltage source converter valve. On the other hand, it is also beneficial to improve the dynamic control performance of the output voltage of the DC energy storage valve, thereby realizing grid-type control of the energy storage system to provide effective inertia support and voltage support for the power grid.

[0077] In a second aspect, the present application provides a virtual synchronization control device for an energy storage system, wherein the energy storage system includes a voltage source converter valve and a DC energy storage valve, and the device includes:

[0078] a first control module, configured to control the output voltage of the DC energy storage valve according to a measured value of an output electrical signal on the DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve;

[0079] The second control module is used to control the output signal of the AC side of the voltage source converter valve according to the measured value of the grid connection point electrical signal of the voltage source converter valve and the reference value of the grid connection point electrical signal.

[0080] In a third aspect, the present application provides a control device for an energy storage system, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps in the embodiment of the virtual synchronous control method for the energy storage system are implemented.

[0081] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps in the embodiment of the virtual synchronous control method for the energy storage system are implemented.

[0082] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the steps in the embodiment of the virtual synchronous control method of the energy storage system described above.

[0083] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0085] FIG1 is a schematic structural diagram of an energy storage system provided in some embodiments of the present application;

[0086] FIG2 is a schematic diagram of a virtual synchronization control framework of an energy storage system provided in some embodiments of the present application;

[0087] FIG3 is a flow chart of a virtual synchronization control method for an energy storage system provided in some embodiments of the present application;

[0088] FIG4 is a flow chart of a virtual synchronization control method for an energy storage system provided in some other embodiments of the present application;

[0089] FIG5 is a flow chart of a method for controlling the output frequency of a voltage source converter valve on the AC side according to some embodiments of the present application;

[0090] FIG6A is a flowchart of a first closed-loop control processing method provided in some embodiments of the present application;

[0091] FIG6B is a schematic flow chart of a first integral processing method provided in some embodiments of the present application;

[0092] FIG6C is a flow chart of a method for controlling an output frequency according to some embodiments of the present application;

[0093] FIG6D is a flow chart of an active power-frequency control method provided in some embodiments of the present application;

[0094] FIG7 is a flow chart of a method for controlling the output voltage amplitude of an AC side of a voltage source converter valve according to some embodiments of the present application;

[0095] FIG8A is a flowchart of a method for determining a first internal potential amplitude of a voltage source converter valve according to some embodiments of the present application;

[0096] FIG8B is a flow chart of a reactive power-voltage control method according to some embodiments of the present application;

[0097] FIG9A is a flow chart of a method for controlling the output voltage amplitude of an AC side of a voltage source converter valve according to some embodiments of the present application;

[0098] FIG9B is a flowchart of a first PI adjustment processing method provided in some embodiments of the present application;

[0099] FIG9C is a flow chart of a dynamic virtual impedance processing method provided in some embodiments of the present application;

[0100] FIG9D is a flow chart of a static virtual impedance processing method provided in some embodiments of the present application;

[0101] FIG10 is a flow chart of a method for adjusting an active power limit value according to some embodiments of the present application;

[0102] FIG11 is a flow chart of a method for adjusting the damping coefficient and the latching coefficient provided in some embodiments of the present application;

[0103] FIG12 is a flow chart of a method for determining a grid connection point fault detection signal according to some embodiments of the present application;

[0104] FIG13A is a flowchart of a method for pre-synchronization processing of an output signal on the AC side of a voltage source converter valve according to some embodiments of the present application;

[0105] FIG13B is a flowchart of a method for determining an output voltage phase angle on the AC side of a voltage source converter valve according to some embodiments of the present application;

[0106] FIG13C is a schematic flow chart of a second closed-loop processing method provided in some embodiments of the present application;

[0107] FIG13D is a schematic flow chart of a second closed-loop processing method provided in some embodiments of the present application;

[0108] FIG14A is a schematic flow chart of a virtual synchronization control method for an energy storage system provided in some other embodiments of the present application;

[0109] FIG14B is a flowchart of a fourth PI adjustment processing method provided in some embodiments of the present application;

[0110] FIG14C is a flowchart of a fifth PI adjustment processing method provided in some embodiments of the present application;

[0111] FIG14D is a flow chart of a method for controlling an output voltage of a DC energy storage valve according to some embodiments of the present application;

[0112] FIG15 is a schematic diagram of a virtual synchronization control framework of an energy storage system provided by some embodiments of the present application;

[0113] FIG16A shows the active power P of the grid connection point, the reactive power Q of the grid connection point, and the AC grid voltage amplitude U provided in an embodiment of the present application. s Schematic diagram of simulation results;

[0114] FIG16B is an output voltage u of a DC energy storage valve provided in an embodiment of the present application. dc , the output current i of the DC side of the voltage source converter valve dc Schematic diagram of simulation results of the output frequency ω on the AC side of the voltage source converter valve;

[0115] FIG17 is a schematic structural diagram of a virtual synchronization control device for an energy storage system provided in some embodiments of the present application;

[0116] FIG18 is a schematic diagram of the structure of a control device of an energy storage system in some embodiments of the present application. DETAILED DESCRIPTION

[0117] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0118] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the term "include" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0119] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is two or more (including two), unless otherwise clearly and specifically defined.

[0120] The virtual synchronous control method, apparatus, device, and storage medium of the energy storage system provided in the embodiments of the present application can be applied to the virtual synchronous control application scenario of the high-voltage direct current energy storage system; of course, it can also be applied to other application scenarios.

[0121] With the rapid development of new power systems dominated by renewable energy, their increasing proportion has led to a lack of inertia and damping in these systems, making them relatively fragile. Therefore, high-voltage, high-capacity energy storage systems with grid-friendly connectivity will become a new development demand and trend. Among these, the ability to support virtual inertia and damping, as well as the ability to form a grid, will become key indicators of the stable operation of these new power systems.

[0122] Typically, grid-connected control strategies for energy storage systems are primarily implemented through virtual synchronous generator (VSG) technology, enabling the system to transition from a current-source grid-following control mode to a voltage-source grid-connected control mode. VSG technology allows the energy storage system to mimic the characteristics of a traditional synchronous generator, making it an independent voltage source capable of independently supplying power to the load while also providing the necessary inertia and damping support for the grid. This research has important implications for the stable operation of new power systems.

[0123] With the advancement of energy storage technology, HVDC energy storage systems have become a significant development direction. HVDC energy storage systems integrate voltage source converters (VSCs) and DC energy storage valves in terms of topology and functionality, offering advantages such as high modularity, economic benefits, and high operational stability. Compared to traditional energy storage systems, HVDC energy storage systems differ in topology and functionality. The DC side of HVDC energy storage systems also requires control, and the virtual synchronization control methods used in traditional energy storage systems are not applicable to HVDC energy storage systems. Therefore, implementing virtual synchronization control for HVDC energy storage systems is an urgent issue that needs to be addressed.

[0124] In addition, the grid-connected inverter or VSC of the VSG technology in the related art can simulate the characteristics of a synchronous generator and has effective inertia and damping support capabilities in the face of fluctuations in grid frequency and voltage amplitude. However, once a serious grid fault occurs (for example, a deep grid voltage drop, etc.), the VSG technology in the related art lacks current or power limiting, resulting in an inability to suppress the fault current impact in the VSC valve, resulting in poor system fault ride-through performance. Another part of the related research introduced virtual impedance / resistance to suppress the impact current, but the current limiting effect of the virtual impedance / resistance under severe short-circuit faults is relatively insufficient, the response speed is slow, and it cannot meet the stability requirements of the new power system.

[0125] In order to solve the problem of how to perform virtual synchronous control on a high-voltage direct current (HVDC) energy storage system in the related art, the embodiment of the present application proposes a virtual synchronous control method for independently controlling the voltage source converter valve and the DC energy storage valve in the energy storage system. The method can be applied to the virtual synchronous control of the high-voltage direct current (HVDC) energy storage system, so as to realize the grid-type control of the high-voltage direct current (HVDC) energy storage system, which is beneficial to improving the low-voltage fault ride-through capability of the energy storage system.

[0126] For ease of understanding, the structure of the energy storage system is first described and illustrated in the embodiments of this application. For example, the energy storage system in the embodiments of this application may include, but is not limited to, a high-voltage direct current (HVDC) energy storage system. Compared to traditional energy storage systems, the high-voltage direct current (HVDC) energy storage system can directly support the operation of voltage source converter valves in a virtual synchronous control mode, has a higher voltage level, a larger capacity, and has stronger grid regulation capabilities and grid support functions.

[0127] In some embodiments, FIG1 is a schematic structural diagram of an energy storage system provided in some embodiments of the present application. As shown in FIG1 , the energy storage system in the embodiments of the present application may include, but is not limited to, a voltage source converter valve 101, a DC energy storage valve 102, and a control device 103 for the energy storage system, wherein the AC side of the voltage source converter valve 101 is connected to an AC power grid 104, and the DC side of the voltage source converter valve 101 is connected to the DC energy storage valve 102. The control device 103 in the embodiments of the present application can be used to control the voltage source converter valve 101 and the DC energy storage valve 102 using the virtual synchronous control method for the energy storage system provided in the embodiments of the present application.

[0128] It should be understood that when the voltage source converter valve 101 and the DC energy storage valve 102 are controlled by different control devices, the control device 103 may include a first sub-control device corresponding to the voltage source converter valve 101 and a second sub-control device corresponding to the DC energy storage valve 102. Correspondingly, the first sub-control device may control the voltage source converter valve 101 using the control method involving the voltage source converter valve 101 in the virtual synchronization control method for the energy storage system provided in the embodiment of the present application, and the second sub-control device may control the DC energy storage valve 102 using the control method involving the DC energy storage valve 102 in the virtual synchronization control method for the energy storage system provided in the embodiment of the present application.

[0129] It should be noted that FIG1 shows an example in which the control device 103 of the energy storage system in the embodiment of the present application is independent of the voltage source converter valve 101 and the DC energy storage valve 102; of course, the control device 103 of the energy storage system can also be integrated into the voltage source converter valve 101 and / or the DC energy storage valve 102.

[0130] In some embodiments, FIG2 is a schematic diagram of a virtual synchronous control framework for an energy storage system provided in some embodiments of the present application. As shown in FIG2 , the energy storage system in the embodiments of the present application may include, but is not limited to, a voltage source converter valve 101, a DC energy storage valve 102, and an energy storage system control device 103. The voltage source converter valve 101 may be connected to an AC power grid 104 via a transformer 105. The parameters in FIG2 may be referenced from Table 1.

[0131] Table 1 is a schematic table of the parameters in Figure 2

[0132] It should be noted that the voltage source converter valve 101 can be directly connected to the AC grid 104 without going through the transformer 105. That is, the transformer 105 in Figure 2 can be omitted. Accordingly, the AC side of the voltage source converter valve does not need to be distinguished between the AC grid side of the voltage source converter valve and the AC valve side of the voltage source converter valve. In other words, the AC grid side of the voltage source converter valve and the AC valve side of the voltage source converter valve are the same.

[0133] For example, the control device 103 in the embodiment of the present application may include, but is not limited to, a voltage source valve control unit 1031 for controlling the voltage source converter valve 101 and a DC energy storage valve control unit 1032 for controlling the DC energy storage valve 102. The voltage source valve control unit 1031 may include, but is not limited to, a fault detection unit 1031A for detecting whether a fault has occurred in the energy storage system, a VSG control unit 1031B, and a voltage and current control unit 1031C.

[0134] The VSG control unit 1031B can be used to implement pre-synchronization processing, active power-frequency control, and / or reactive power-voltage control of the voltage source converter valve. The voltage and current control unit 1031C can be used for voltage outer loop control processing and / or current limiting inner loop processing.

[0135] The DC energy storage valve control unit 1032 may include but is not limited to: a DC voltage outer loop control unit 1032A for DC voltage outer loop processing and a DC current inner loop control unit 1032B for DC current inner loop processing.

[0136] It should be noted that the following embodiments of this application will provide an exemplary introduction and description of the relevant contents of the above-mentioned different processing.

[0137] Any measurement value involved in the embodiments of the present application may include, but is not limited to, a per-unit value of the measurement value, and / or a nominal value (or non-per-unit value) of the measurement value.

[0138] It should be understood that per-unit value is a relative unit system and a numerical notation method commonly used in power system analysis and engineering calculations. It represents the relative value of each physical quantity (nominal value) relative to a certain reference value, and the unit is pu (it can also be considered dimensionless).

[0139] Any reference value involved in the embodiments of the present application may include but is not limited to a per-unit value of the reference value, and / or a nominal value of the reference value.

[0140] In some embodiments, FIG3 is a flow chart of a virtual synchronization control method for an energy storage system provided in some embodiments of the present application. In the embodiments of the present application, the method is described by applying the method to a virtual synchronization control device of the above-mentioned energy storage system as an example. For example, the energy storage system in the embodiments of the present application may include, but is not limited to, a voltage source converter valve and a DC energy storage valve. As shown in FIG3 , the method of the embodiments of the present application may include the following steps:

[0141] Step S301: Control the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve.

[0142] Illustratively, the output electrical signal measurement value of the DC side of the voltage source converter valve in the embodiments of the present application may include but is not limited to the output voltage measurement value of the DC side of the voltage source converter valve, and / or the output current measurement value of the DC side of the voltage source converter valve.

[0143] In this step, the virtual synchronous control device can control the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve.

[0144] Exemplarily, the virtual synchronous control device can perform DC voltage outer loop processing and / or DC current inner loop processing based on the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve to obtain the output voltage command value of the DC energy storage valve, so that the output voltage of the DC energy storage valve can be controlled according to the output voltage command value.

[0145] The DC voltage outer loop processing in the embodiment of the present application may include but is not limited to proportional and integral (PI) regulation processing based on the DC voltage difference between the output voltage measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve.

[0146] The DC current inner loop processing in the embodiment of the present application may include but is not limited to PI regulation processing based on the DC current difference between the output current measurement value of the DC side of the voltage source converter valve and the output current reference value of the DC energy storage valve.

[0147] It can be seen that in this step, the output voltage of the DC energy storage valve can be independently controlled based on the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve.

[0148] Step S302: Control the output signal of the AC side of the voltage source converter valve according to the measured value of the grid connection point electrical signal of the voltage source converter valve and the reference value of the grid connection point electrical signal.

[0149] For example, the grid connection point electrical signal measurement value in the embodiment of the present application may include but is not limited to at least one of the following: a grid connection point active power measurement value, a grid connection point reactive power measurement value, and a grid connection point voltage measurement value.

[0150] Illustratively, the grid connection point electrical signal reference value in the embodiment of the present application may include but is not limited to at least one of the following: a grid connection point active power reference value, a grid connection point reactive power reference value, and a grid connection point voltage reference value.

[0151] In this step, the virtual synchronization control device can control the output signal of the AC side of the voltage source converter valve by controlling the output frequency and / or output voltage amplitude of the AC side of the voltage source converter valve based on the grid connection point electrical signal measurement value and grid connection point electrical signal reference value of the voltage source converter valve.

[0152] Exemplarily, when the voltage source converter valve 101 is connected to the AC grid 104 through the transformer 105, the AC side of the voltage source converter valve in the embodiment of the present application may include: the AC grid side of the voltage source converter valve, and / or the AC valve side of the voltage source converter valve.

[0153] As another example, when the voltage source converter valve 101 is directly connected to the AC power grid 104, the AC side of the voltage source converter valve in the embodiment of the present application does not need to be distinguished between the AC grid side of the voltage source converter valve and the AC valve side of the voltage source converter valve, or in other words, the AC grid side of the voltage source converter valve and the AC valve side of the voltage source converter valve are the same.

[0154] It can be seen that in this step, the output signal of the AC side of the voltage source converter valve can be independently controlled based on the measured value of the grid connection point electrical signal of the voltage source converter valve and the reference value of the grid connection point electrical signal.

[0155] The above-mentioned virtual synchronous control method for the energy storage system controls the output voltage of the DC energy storage valve based on the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve. Furthermore, the output signal of the AC side of the voltage source converter valve is controlled based on the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve. In the embodiment of the present application, the output voltage of the DC energy storage valve can be independently controlled based on the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve, and the output signal of the AC side of the voltage source converter valve can be independently controlled based on the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve. It can be seen that the embodiment of the present application realizes a virtual synchronous control method for independently controlling the voltage source converter valve and the DC energy storage valve in the energy storage system, and thus can be applied to the virtual synchronous control of the high-voltage direct current energy storage system, so as to realize the grid-type control of the high-voltage direct current energy storage system, which is beneficial to improving the low-voltage fault ride-through capability of the energy storage system. In addition, by independently controlling the voltage source converter valve and the DC energy storage valve in the energy storage system, the voltage source converter valve does not need to take into account both DC side control and AC side control, thereby simplifying the complexity of the control loop of the voltage source converter valve.

[0156] In some embodiments, FIG4 is a flow chart of a virtual synchronous control method for an energy storage system provided in other embodiments of the present application. On the basis of the above embodiments, the embodiments of the present application introduce the relevant contents of "controlling the output signal of the AC side of the voltage source converter valve according to the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve" in the above step S302. For example, the grid connection point electrical signal measurement value in the embodiments of the present application may include but is not limited to: grid connection point active power measurement value, grid connection point reactive power measurement value and grid connection point voltage measurement value; the grid connection point electrical signal reference value may include but is not limited to: grid connection point active power reference value, grid connection point reactive power reference value and grid connection point voltage reference value. As shown in FIG4 , the above step S302 may include the following steps:

[0157] Step S3021: Control the output frequency of the AC side of the voltage source converter valve according to the measured active power value of the grid connection point and the active power reference value of the grid connection point.

[0158] In this step, the virtual synchronization control device can control the output frequency of the AC side of the voltage source converter valve based on the active power measurement value of the grid connection point and the active power reference value of the grid connection point, thereby realizing active power-frequency control of the voltage source converter valve so that the active power of the grid connection point can be adjusted to the active power reference value of the grid connection point.

[0159] Exemplarily, the virtual synchronization control device controls the output frequency of the AC side of the voltage source converter valve by controlling the grid connection point active power deviation between the grid connection point active power measurement value and the grid connection point active power reference value, so that the grid connection point active power can be adjusted to the grid connection point active power reference value.

[0160] Step S3022: Control the output voltage amplitude of the AC side of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value, and the grid connection point voltage reference value.

[0161] In this step, the virtual synchronization control device can control the output voltage amplitude of the AC side of the voltage source converter valve based on the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value, thereby realizing reactive power-voltage control of the voltage source converter valve so that the grid connection point voltage can be adjusted to the grid connection point voltage reference value.

[0162] Exemplarily, the virtual synchronization control device controls the output voltage amplitude on the AC side of the voltage source converter valve based on the grid point reactive power deviation between the grid point reactive power measurement value and the grid point reactive power reference value, and / or the grid point voltage deviation between the grid point voltage measurement value and the grid point voltage reference value, so that the grid point voltage can be adjusted to the grid point voltage reference value.

[0163] In summary, in the embodiment of the present application, the output frequency of the AC side of the voltage source converter valve is controlled based on the grid-connected active power measurement value and the grid-connected active power reference value. Furthermore, the output voltage amplitude of the AC side of the voltage source converter valve is controlled based on the grid-connected reactive power measurement value, the grid-connected voltage measurement value, the grid-connected reactive power reference value, and the grid-connected voltage reference value. It can be seen that in the embodiment of the present application, active power-frequency control of the voltage source converter valve is achieved based on the grid-connected active power measurement value and the grid-connected active power reference value, and reactive power-voltage control of the voltage source converter valve is achieved based on the grid-connected reactive power measurement value, the grid-connected voltage measurement value, the grid-connected reactive power reference value, and the grid-connected voltage reference value, thereby achieving virtual synchronous control of the active power and reactive power decoupling of the voltage source converter valve, which is beneficial to the transient support of the grid-connected frequency and grid-connected voltage, thereby further improving the low-voltage fault ride-through capability of the energy storage system.

[0164] In some embodiments, FIG5 is a flow chart of a method for controlling the output frequency of the AC side of a voltage source converter valve provided in some embodiments of the present application. Based on the above embodiments, the present embodiment provides an exemplary description of the relevant content of step S3021, "controlling the output frequency of the AC side of the voltage source converter valve based on the measured active power value at the grid connection point and the active power reference value at the grid connection point." As shown in FIG5 , step S3021 may include the following steps:

[0165] Step S501: Determine the active power deviation of the grid connection point according to the measured active power value of the grid connection point and the active power reference value of the grid connection point.

[0166] In this step, the virtual synchronization control device can determine the active power deviation of the grid connection point based on the active power measurement value of the grid connection point and the active power reference value of the grid connection point, so as to control the output frequency of the AC side of the voltage source converter valve based on the active power deviation of the grid connection point, thereby realizing active power-frequency control of the voltage source converter valve.

[0167] It should be noted that the active power-frequency control of the voltage source converter valve involved in the embodiment of the present application can convert the active power deviation of the grid connection point into the output frequency of the AC side of the voltage source converter valve by simulating the rotor inertia and speed regulator droop characteristics of the synchronous machine.

[0168] In a possible implementation, the virtual synchronization control device may subtract the grid connection point active power reference value from the grid connection point active power measurement value to obtain the grid connection point active power deviation.

[0169] In another possible implementation method, the virtual synchronization control device can limit the active power reference value of the grid connection point according to the maximum active power limit value and the minimum active power limit value to obtain the active power reference value of the grid connection point after limiting, and subtract the active power reference value of the grid connection point after limiting from the active power measurement value of the grid connection point to obtain the active power deviation of the grid connection point.

[0170] In this implementation, the virtual synchronous control device can limit the grid connection point active power reference value based on the maximum active power limit value and the minimum active power limit value, so that the limited grid connection point active power reference value can meet the actual capacity of the energy storage system. The maximum active power limit value refers to the maximum active power limit value of the grid connection point, and the minimum active power limit value refers to the minimum active power limit value of the grid connection point.

[0171] It should be noted that the maximum active power limit value and the minimum active power limit value in the embodiment of the present application can be preset values, or can be values ​​adjusted in real time based on the grid connection point fault detection signal. The grid connection point fault detection signal can be used to indicate whether a fault has occurred in the energy storage system.

[0172] For example, if the grid connection point active power reference value is greater than the active power maximum limit value, the virtual synchronization control device may use the active power maximum limit value as the grid connection point active power reference value after limit.

[0173] As another example, if the grid connection point active power reference value is less than or equal to the maximum active power limit value, and greater than or equal to the minimum active power limit value, the virtual synchronization control device can use the grid connection point active power reference value as the grid connection point active power reference value after limiting.

[0174] In another exemplary embodiment, if the grid connection point active power reference value is less than the active power minimum limit value, the virtual synchronization control device may use the active power minimum limit value as the grid connection point active power reference value after limit.

[0175] Furthermore, the virtual synchronous control device can subtract the limited grid-connected point active power reference value from the grid-connected point active power measurement value to obtain the grid-connected point active power deviation, so that the output frequency of the AC side of the voltage source converter valve can be more accurately controlled according to the grid-connected point active power deviation.

[0176] Step S502: Perform a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result.

[0177] In this step, the virtual synchronous control device can perform a first closed-loop control process on the active power deviation at the grid connection point so that it can be controlled according to the feedback signal, thereby facilitating obtaining an accurate closed-loop result. The first closed-loop control process can include, but is not limited to, a closed-loop control method based on a damping coefficient as a feedback coefficient, the product of an inertia time constant and a preset coefficient C as an integral coefficient, and a latch coefficient as a proportional coefficient.

[0178] For example, FIG6A is a flow chart of a first closed-loop control processing method provided in some embodiments of the present application. As shown in FIG6A , the virtual synchronous control device can determine a first feedback signal based on historical closed-loop results and a damping coefficient D, and perform a first integral process on the difference signal between the grid connection point active power deviation and the first feedback signal to obtain a closed-loop result. The historical closed-loop result may include, but is not limited to, the result obtained by the virtual synchronous control device performing the last first closed-loop control process on the historical grid connection point active power deviation (or the grid connection point active power deviation at the previous moment).

[0179] In an embodiment of the present application, the virtual synchronous control device may multiply the historical closed-loop result by the damping coefficient D to obtain a first feedback signal. Furthermore, the virtual synchronous control device may subtract the grid connection point active power deviation from the first feedback signal to obtain a difference signal, and perform a first integration on the difference signal to obtain a closed-loop result.

[0180] It should be noted that the damping coefficient D in the embodiment of the present application may be a preset value, or may be a value adjusted in real time according to a grid connection point fault detection signal.

[0181] For example, FIG6B is a flowchart of a first integral processing method provided by some embodiments of the present application. As shown in FIG6B , the virtual synchronous control device can be configured to generate a first integral processing method according to the inertia time constant H and the latch coefficient f SH Perform a first integration process on the difference signal to obtain a closed-loop result.

[0182] In the embodiment of the present application, the virtual synchronous control device can use the product of the inertia time constant H and the preset coefficient C as the integral coefficient and the latch coefficient f SH As a proportional coefficient, the difference signal is first integrated to obtain a closed-loop result. For example, the preset coefficient C may include but is not limited to 2.

[0183] It should be noted that the latch coefficient f in the embodiment of the present application is SH It can be a preset value, or a value adjusted in real time according to a grid connection point fault detection signal.

[0184] Step S503: Control the output frequency according to the closed-loop result and the rated angular frequency of the power grid.

[0185] In this step, the virtual synchronous control device can control the output frequency according to the closed-loop result and the grid rated angular frequency, wherein the grid rated angular frequency may include but is not limited to the grid rated angular frequency per unit value, and / or the grid rated angular frequency nominal value (or non-per-unit value).

[0186] For example, FIG6C is a flow chart of the output frequency control method provided in some embodiments of the present application. As shown in FIG6C , the virtual synchronous control device can compare the closed-loop result with the grid rated angular frequency per unit value ω n，pu Perform the summation and then compare the summation result with the nominal value of the grid rated angular frequency ω n Perform multiplication to obtain the output frequency ω VSG .

[0187] For ease of understanding, the following embodiments of the present application introduce the overall process of the active power-frequency control method of the voltage source converter valve. Figure 6D is a flow chart of the active power-frequency control method provided by some embodiments of the present application. As shown in Figure 6D, the virtual synchronous control device can be controlled by the maximum active power limit value P lim,max and the minimum active power limit value P lim,min The reference value of active power per unit value P at the grid connection point ref，pu Perform limiting processing to obtain the active power reference value of the grid connection point after limiting.

[0188] Furthermore, the virtual synchronous control device can compare the active power reference value of the grid connection point after limiting with the per-unit value of the active power measurement value of the grid connection point P pu Subtract the two to get the active power deviation of the grid connection point.

[0189] Furthermore, the virtual synchronous control device can obtain a closed-loop result by performing a first closed-loop control process on the active power deviation of the grid connection point. The implementation of the first closed-loop control process can refer to the relevant content of the above embodiment and will not be repeated here.

[0190] Furthermore, the virtual synchronous control device can compare the closed-loop result with the grid rated angular frequency per unit value ω n，pu Perform the summation and then compare the summation result with the nominal value of the grid rated angular frequency ω n Perform multiplication to obtain the output frequency ω VSG and by the output frequency ω VSG The reference phase angle θ can be obtained by integration VSG , so that it can achieve autonomous synchronization with the grid frequency and phase.

[0191] It should be noted that the maximum active power limit value P in the embodiment of the present application islim,max , the minimum limit value of active power P lim,min , damping coefficient D or latching coefficient f SH It can be based on the grid fault detection signal f sig The value is adjusted in real time so that the active power reference value of the energy storage system does not exceed the actual system capacity during a fault, thereby improving the transient stability of the energy storage system during the fault. Among them, the grid connection point fault detection signal can be used to indicate whether the energy storage system has a fault.

[0192] In the embodiment of the present application, when the reference phase angle θ VSG When the phase angle θ is greater than the grid connection point, or the grid connection point active power is greater than the grid connection point active power reference value, the virtual synchronous control device will reduce the output frequency of the AC side of the voltage source converter valve through the VSG active power-frequency control method, thereby reducing the output phase angle, and finally adjusting the grid connection point active power to the grid connection point active power reference value per unit value P ref，pu , and the grid connection point frequency and grid connection point phase are synchronized with the grid frequency and grid phase respectively.

[0193] In summary, in the embodiments of the present application, the grid connection point active power deviation is determined based on the measured grid connection point active power value and the grid connection point active power reference value. Furthermore, a first closed-loop control process is performed on the grid connection point active power deviation to obtain a closed-loop result, and the output frequency is controlled based on the closed-loop result and the rated grid angular frequency. It can be seen that the active power-frequency control of the voltage source converter valve in the embodiments of the present application, by converting the grid connection point active power deviation into the output frequency of the AC side of the voltage source converter valve, facilitates adjusting the grid connection point active power to the grid connection point active power reference value.

[0194] In some embodiments, FIG7 is a flow chart illustrating a method for controlling the output voltage amplitude on the AC side of a voltage source converter valve provided in some embodiments of the present application. Based on the above embodiments, the present embodiments provide an exemplary description of the content of step S3022, "controlling the output voltage amplitude on the AC side of the voltage source converter valve based on the measured grid-connection point reactive power value, the measured grid-connection point voltage value, the grid-connection point reactive power reference value, and the grid-connection point voltage reference value." As shown in FIG7 , step S3022 may include the following steps:

[0195] Step S701: Determine a first internal potential amplitude of a voltage source converter valve according to a measured reactive power value at a grid connection point, a measured voltage value at a grid connection point, a reference reactive power value at a grid connection point, and a reference voltage value at a grid connection point.

[0196] In this step, the virtual synchronous control device can determine the grid point reactive power deviation and the grid point voltage deviation based on the grid point reactive power measurement value, the grid point voltage measurement value, the grid point reactive power reference value and the grid point voltage reference value, so that the first internal potential amplitude of the voltage source converter valve, that is, the output voltage amplitude of the AC valve side of the voltage source converter valve, can be determined based on the grid point reactive power deviation and / or the grid point voltage deviation, thereby realizing reactive power-voltage control of the voltage source converter valve.

[0197] It should be noted that the reactive power-voltage control of the voltage source converter valve involved in the embodiment of the present application can convert the grid connection point reactive power deviation and grid connection point voltage deviation into the first internal potential amplitude of the voltage source converter valve by simulating the excitation regulation equation of the synchronous machine.

[0198] For example, FIG8A is a flowchart illustrating a method for determining a first internal potential amplitude of a voltage source converter valve provided in some embodiments of the present application. Based on the above embodiments, the present embodiments provide an exemplary description of the content related to "determining the first internal potential amplitude of the voltage source converter valve based on the measured grid connection point reactive power value, the measured grid connection point voltage value, the grid connection point reactive power reference value, and the grid connection point voltage reference value" in step S701. As shown in FIG8A , step S701 may include the following steps:

[0199] Step S7011: Determine the reactive power deviation of the grid connection point according to the reactive power measurement value of the grid connection point and the reactive power reference value of the grid connection point.

[0200] In this step, the virtual synchronous control device can determine the grid connection point reactive power deviation based on the grid connection point reactive power measurement value and the grid connection point reactive power reference value, so as to determine the first internal potential amplitude of the voltage source converter valve based on the grid connection point reactive power deviation.

[0201] Exemplarily, the virtual synchronous control device may perform a subtraction process on the grid connection point reactive power reference value and the grid connection point reactive power measurement value to obtain the grid connection point reactive power deviation.

[0202] Step S7012: Determine the grid connection point voltage deviation according to the grid connection point voltage measurement value and the grid connection point voltage reference value.

[0203] In this step, the virtual synchronous control device can determine the grid connection point voltage deviation based on the grid connection point voltage measurement value and the grid connection point voltage reference value, so as to determine the first internal potential amplitude of the voltage source converter valve based on the grid connection point voltage deviation.

[0204] Exemplarily, the virtual synchronous control device may perform a subtraction process on the grid connection point voltage reference value and the grid connection point voltage measurement value to obtain the grid connection point voltage deviation.

[0205] Step S7013: Perform a second integration process based on the reactive power deviation of the grid connection point and / or the voltage deviation of the grid connection point to obtain a first internal potential amplitude.

[0206] In this step, the virtual synchronous control device may perform a second integration process based on the reactive power deviation of the grid connection point and / or the voltage deviation of the grid connection point to obtain the first internal potential amplitude.

[0207] In a possible implementation, the virtual synchronous control device may obtain the first internal potential amplitude by performing a second integration process on the reactive power deviation of the grid connection point or the adjusted reactive power deviation of the grid connection point.

[0208] In another possible implementation, the virtual synchronous control device may obtain the first internal potential amplitude by performing a second integration process on the grid connection point voltage deviation or the adjusted grid connection point voltage deviation.

[0209] In another possible implementation, the virtual synchronous control device may determine a deviation sum based on the grid connection point reactive power deviation and the grid connection point voltage deviation, and perform a second integral process on the deviation sum to obtain the first internal potential amplitude. The deviation sum may include but is not limited to the first deviation sum or the second deviation sum.

[0210] Exemplarily, the virtual synchronous control device may obtain a first deviation sum by summing the grid connection point reactive power deviation and the grid connection point voltage deviation, and perform a second integration process on the first deviation sum to obtain a first internal potential amplitude.

[0211] As another example, the virtual synchronous control device can adjust the reactive power deviation and the grid connection point voltage deviation respectively, and add the adjusted grid connection point reactive power deviation and the adjusted grid connection point voltage deviation to obtain a second deviation sum; further, the virtual synchronous control device can perform a second integral processing on the second deviation sum to obtain a first internal potential amplitude.

[0212] In order to make the first internal potential amplitude more consistent with the actual capacity of the energy storage system, the virtual synchronous control device can perform a second integration process based on the reactive power deviation at the grid connection point and / or the voltage deviation at the grid connection point to obtain a first initial internal potential amplitude, and then limit the first initial internal potential amplitude based on the maximum internal potential amplitude and the minimum internal potential amplitude to obtain the first internal potential amplitude. The maximum internal potential amplitude refers to the maximum internal potential amplitude on the AC side of the voltage source converter valve, and the minimum internal potential amplitude refers to the minimum internal potential amplitude on the AC side of the voltage source converter valve.

[0213] It should be noted that the maximum amplitude of the internal potential and the minimum amplitude of the internal potential in the embodiment of the present application can be preset values, or can be values ​​obtained by other means.

[0214] For example, if the first initial internal potential amplitude is greater than the maximum internal potential amplitude, the virtual synchronous control device may use the maximum internal potential amplitude as the first internal potential amplitude.

[0215] As another example, if the first initial internal potential amplitude is less than or equal to the maximum internal potential amplitude and greater than or equal to the minimum internal potential amplitude, the virtual synchronous control device may use the first initial internal potential amplitude as the first internal potential amplitude.

[0216] As another example, if the first initial internal potential amplitude is smaller than the minimum internal potential amplitude, the virtual synchronous control device may use the minimum internal potential amplitude as the first internal potential amplitude.

[0217] It can be seen that in the embodiment of the present application, by limiting the first initial internal potential amplitude according to the maximum internal potential amplitude and the minimum internal potential amplitude, a more accurate first internal potential amplitude can be obtained, so that the output voltage amplitude on the AC side of the voltage source converter valve can be more accurately controlled according to the first internal potential amplitude.

[0218] For ease of understanding, the following embodiments of the present application introduce the overall process of the reactive power-voltage control method of the voltage source converter valve. Figure 8B is a flow chart of the reactive power-voltage control method provided by some embodiments of the present application. As shown in Figure 8B, the virtual synchronous control device can set the grid point reactive power reference value per unit value Q ref,pu The measured value of reactive power at the grid connection point is Q pu Subtract the two to get the reactive power deviation of the grid connection point.

[0219] Furthermore, the virtual synchronous control device can standardize the grid voltage reference value u s,ref,pu The measured value of the grid voltage is u s,pu Subtract the two and get the voltage deviation of the grid connection point.

[0220] Furthermore, the virtual synchronous control device can be used to adjust the reactive power droop coefficient K q Adjust the reactive power deviation of the grid connection point to obtain the adjusted reactive power deviation of the grid connection point and the voltage droop coefficient K. v The grid connection point voltage deviation is adjusted to obtain an adjusted grid connection point voltage deviation. Further, the virtual synchronous control device can add the adjusted grid connection point reactive power deviation and the adjusted grid connection point voltage deviation to obtain a second deviation sum.

[0221] It should be noted that by changing the reactive droop coefficient K q and / or voltage droop factor K v The value of can realize the switching of reactive power-voltage control mode. qis 1, K v When it is 0, it corresponds to constant reactive power control; when K q is 0, K v When it is 1, it corresponds to constant voltage control; when K q and K v When both are not 0, it corresponds to reactive power-voltage droop control. q and K v By selecting appropriate values, adaptive regulation of the reactive power at the grid connection point can be achieved during system faults and fault recovery processes to support the stability of the grid connection point voltage.

[0222] Furthermore, the virtual synchronous control device can control the integral coefficient K according to the first internal potential Ei1 A second integration process is performed on the second deviation and φ to obtain the first initial internal potential amplitude.

[0223] Furthermore, the virtual synchronous control device can be configured to control the maximum internal potential E max and the minimum amplitude of the internal potential E min The first initial internal potential amplitude is limited to obtain a first internal potential amplitude E.

[0224] It can be seen that the reactive power-voltage control in the embodiment of the present application simulates the excitation regulation equation of the synchronous machine, takes the deviation corresponding to the reactive power deviation and the voltage deviation of the grid connection point as the error signal, and integrates it through an integrator to obtain the first internal potential amplitude.

[0225] Step S702: Control the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude of the voltage source converter valve.

[0226] In this step, the virtual synchronous control device can control the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude of the voltage source converter valve.

[0227] Exemplarily, the virtual synchronous control device may control the output voltage amplitude of the AC side of the voltage source converter valve by performing voltage outer loop control processing and / or current limiting inner loop processing according to the first internal potential amplitude of the voltage source converter valve.

[0228] The voltage outer loop control processing in the embodiment of the present application can be used to include but is not limited to PI adjustment processing based on the first inner potential amplitude and the grid connection point voltage measurement value, dynamic virtual impedance processing or static virtual impedance processing.

[0229] The current limiting inner loop processing in the embodiments of the present application may include but is not limited to current limiting processing and / or current inner loop processing.

[0230] For example, FIG9A is a flowchart illustrating a method for controlling the output voltage amplitude on the AC side of a voltage source converter valve provided in some embodiments of the present application. Based on the above embodiments, the present embodiment provides an exemplary description of the content related to "controlling the output voltage amplitude on the AC side of the voltage source converter valve based on the first internal potential amplitude of the voltage source converter valve" in step S702. As shown in FIG9A , step S702 may include the following steps:

[0231] Step S7021: Perform voltage outer loop control processing according to the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop.

[0232] In this step, the virtual synchronous control device can perform voltage outer loop control processing according to the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain the current command value of the current inner loop.

[0233] Illustratively, the grid connection point voltage measurement value in the embodiments of the present application may include, but is not limited to, a first-axis voltage measurement component and / or a second-axis voltage measurement component. For example, the first-axis voltage measurement component may be a q-axis component measurement value of the grid connection point voltage in a dq coordinate system (or referred to as the q-axis component measurement value of the output voltage on the AC grid side of the voltage source converter valve in the dq coordinate system), and the second-axis voltage measurement component may be a d-axis component measurement value of the grid connection point voltage in a dq coordinate system (or referred to as the d-axis component measurement value of the output voltage on the AC grid side of the voltage source converter valve in the dq coordinate system).

[0234] The voltage outer loop control process in the embodiment of the present application may include but is not limited to any of the following: a first PI adjustment process, a dynamic virtual impedance process, or a static virtual impedance process.

[0235] The current command value of the inner current loop in the embodiments of the present application may include, but is not limited to, a first-axis current component command value of the inner current loop, and / or a second-axis current component command value of the inner current loop. For example, the first-axis current component command value of the inner current loop may be a q-axis component command value of the current of the inner current loop (or the output current of the AC valve side of the voltage source converter valve) in the dq coordinate system, and the second-axis current component command value may be a d-axis component command value of the current of the inner current loop (or the output current of the AC valve side of the voltage source converter valve) in the dq coordinate system.

[0236] Exemplarily, the virtual synchronous control device can obtain the current command value of the inner current loop by performing a first PI adjustment process, a dynamic virtual impedance process or a static virtual impedance process on the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value.

[0237] For example, FIG9B is a flow chart of a first PI adjustment processing method provided in some embodiments of the present application. As shown in FIG9B , in the embodiment of the present application, on the one hand, the virtual synchronous control device can convert the first internal potential amplitude E and the d-axis component measurement value u of the grid connection point voltage in the dq coordinate system into a unit value. d1,pu Perform subtraction processing and perform PI processing on the subtraction result to obtain the d-axis component command value per unit value i of the current inner loop in the dq coordinate system. d2,cmd,pu On the other hand, the virtual synchronous control device can convert the zero and grid-connected point voltage into the q-axis component measured value u in the dq coordinate system. q1,pu By performing subtraction processing and performing PI processing on the subtraction result, the q-axis component command value per unit value i of the current inner loop in the dq coordinate system can be obtained. q2,cmd,pu .

[0238] For example, FIG9C is a flow chart of a dynamic virtual impedance processing method provided by some embodiments of the present application. As shown in FIG9C, in the embodiment of the present application, on the one hand, the virtual synchronous control device can convert the first internal potential amplitude E and the d-axis component measurement value u of the grid connection point voltage in the dq coordinate system into a unit value. d1,pu Subtract the current from the inner loop of the historical current and compare it with the q-axis component command value per unit value and the virtual reactance X in the dq coordinate system. v Furthermore, the virtual synchronous control device can process the summed result as shown in the first branch of FIG9C to obtain the d-axis component command value per unit value i of the current in the current inner loop in the dq coordinate system. d2,cmd,pu Among them, R v represents the virtual resistance, and s represents the differential after Laplace transformation.

[0239] On the other hand, the virtual synchronous control device can convert the zero and grid-connected point voltage into the q-axis component measured value u in the dq coordinate system. q1,pu Subtract the current from the inner loop of the historical current and compare it with the d-axis component command value per unit value and the virtual reactance X in the dq coordinate system. v Further, the virtual synchronous control device can perform the fourth branch processing on the subtraction result as shown in FIG9C , and the q-axis component instruction value per unit value i of the current inner loop in the dq coordinate system can be obtained. q2,cmd,pu .

[0240] For example, FIG9D is a flow chart of a static virtual impedance processing method provided by some embodiments of the present application. As shown in FIG9D , the virtual synchronous control device can convert the first internal potential amplitude E and the d-axis component measurement value u of the grid connection point voltage in the dq coordinate system into a unit value. d1,puPerform subtraction processing to obtain the first subtraction result, and standardize the q-axis component measurement value u of the grid-connected point voltage in the dq coordinate system to zero. q1,pu A subtraction process is performed to obtain a second subtraction result.

[0241] Furthermore, the virtual synchronous control device can perform the first branch processing shown in FIG9D on the first subtraction result to obtain a first processing result, and perform the third branch processing shown in FIG9D on the second subtraction result to obtain a third processing result. Furthermore, the virtual synchronous control device can add the first processing result and the third processing result to obtain the d-axis component command value per unit value i of the current in the current inner loop in the dq coordinate system. d2,cmd,pu .

[0242] Furthermore, the virtual synchronous control device can perform the second branch processing shown in FIG9D on the first subtraction result to obtain a second processing result, and perform the fourth branch processing shown in FIG9D on the second subtraction result to obtain a fourth processing result. Furthermore, the virtual synchronous control device can perform the subtraction processing on the fourth processing result from the second processing result to obtain the q-axis component command value per unit value i of the current in the current inner loop in the dq coordinate system. q2,cmd,pu .

[0243] Step S7022: Perform current limiting inner loop processing according to the current command value to obtain an output voltage signal of the AC side of the voltage source converter valve.

[0244] Exemplarily, the current limiting inner loop processing in the embodiments of the present application may include but is not limited to: current limiting processing, and / or current inner loop processing.

[0245] The output voltage signal of the AC side of the voltage source converter valve in the embodiments of the present application may include, but is not limited to: a first-axis output voltage component of the AC side of the voltage source converter valve, and / or a second-axis output voltage component of the AC side of the voltage source converter valve. For example, the first-axis output voltage component of the AC side of the voltage source converter valve may be the q-axis component of the output voltage of the AC side of the voltage source converter valve in a dq coordinate system, and the second-axis output voltage component of the AC side of the voltage source converter valve may be the d-axis component of the output voltage of the AC side of the voltage source converter valve in a dq coordinate system.

[0246] In this step, the virtual synchronous control device may perform current limiting processing on the current command value to obtain a current command value after limiting (or referred to as an output current reference value on the AC side of the voltage source converter valve). Furthermore, the virtual synchronous control device may perform current inner loop processing on the current command value after limiting to obtain an output voltage signal on the AC side of the voltage source converter valve.

[0247] Exemplarily, the virtual synchronous control device may perform current inner loop processing on the current command value after limiting according to the output current measurement value and the output voltage measurement value of the AC side of the voltage source converter valve.

[0248] Step S7023: Control the output voltage amplitude of the AC side of the voltage source converter valve according to the output voltage signal of the AC side of the voltage source converter valve.

[0249] In this step, the virtual synchronous control device may generate a first control signal based on the output voltage signal of the AC side of the voltage source converter valve, wherein the first control signal is used to control the output voltage amplitude of the AC side of the voltage source converter valve.

[0250] Exemplarily, the virtual synchronous control device may perform coordinate system conversion processing on the output voltage signal of the AC side of the voltage source converter valve to obtain a converted output voltage signal of the AC side of the voltage source converter valve, and generate a first control signal based on the converted output voltage signal of the AC side of the voltage source converter valve. The coordinate system conversion processing may include, but is not limited to, converting from a dq coordinate system to an abc coordinate system; and the converted output voltage signal of the AC side of the voltage source converter valve may include, but is not limited to, the output voltage of the AC side of the voltage source converter valve in the abc coordinate system.

[0251] In the embodiments of the present application, an outer voltage control loop and an inner current limiting loop are sequentially performed based on the first internal potential amplitude of the voltage source converter valve and the measured grid connection point voltage value to obtain an output voltage signal on the AC side of the voltage source converter valve. The output voltage amplitude on the AC side of the voltage source converter valve is then controlled based on the output voltage signal on the AC side of the voltage source converter valve. This demonstrates that the embodiments of the present application accurately control the output voltage amplitude on the AC side of the voltage source converter valve based on the first internal potential amplitude of the voltage source converter valve.

[0252] In summary, in the embodiments of the present application, a first internal potential amplitude of the voltage source converter valve is determined based on the measured grid connection point reactive power value, the measured grid connection point voltage value, the grid connection point reactive power reference value, and the grid connection point voltage reference value. Furthermore, the output voltage amplitude of the AC side of the voltage source converter valve is controlled based on the first internal potential amplitude of the voltage source converter valve. It can be seen that the reactive power-voltage control of the voltage source converter valve in the embodiments of the present application facilitates adjusting the grid connection point voltage to the grid connection point voltage reference value by converting the grid connection point reactive power deviation and / or the grid connection point voltage deviation into the first internal potential amplitude of the voltage source converter valve and controlling the output voltage amplitude of the AC side of the voltage source converter valve based on the first internal potential amplitude.

[0253] In some embodiments, based on the above embodiments, the adjustment process of the above-mentioned maximum active power limit value and the minimum active power limit value is exemplarily introduced and explained in the embodiments of the present application.

[0254] In order to ensure that the active power reference value does not exceed the actual capacity of the system during the fault period and to alleviate the problem of voltage and active power swing at the grid connection point, in the embodiment of the present application, the virtual synchronization control device of the energy storage system can also adjust the maximum active power limit value P according to the grid connection point fault detection signal. lim,max and the minimum active power limit value.

[0255] In a possible implementation, the virtual synchronization control device detects a grid connection point fault detection signal f sig It is used to indicate that the energy storage system has a fault and the maximum active power limit value P lim,max Adjust to the target power maximum limit value P lim,max,pu , and the minimum active power limit value P lim,min Adjust to the target power minimum limit value P lim,min,pu .

[0256] For example, if the grid connection point fault detection signal f sig is the first preset signal, then the grid fault detection signal f sig It can be used to indicate that the energy storage system has failed; if the grid connection point fault detection signal f sig is the second preset signal, then the grid fault detection signal f sig It can be used to indicate that the energy storage system has no faults. For example, the first preset signal can be 1 and the second preset signal can be 0.

[0257] It should be understood that when the energy storage system is fault-free, the maximum active power limit value P lim,max It can be used to preset the maximum power limit value and the minimum active power limit value P lim,min The preset minimum power limit value may be, for example, 1 pu, and the preset minimum power limit value may be -1 pu.

[0258] For example, the target power maximum limit value P in the embodiment of the present application is lim,max,pu and the target power minimum limit value P lim,min,pu They are all related to the measured reactive power and voltage at the grid connection point, and the magnitude of the voltage drop at the grid connection point during the fault period. The measured reactive power and voltage at the grid connection point can correspond to the feasible region of the grid connection point voltage, and the magnitude of the voltage drop at the grid connection point during the fault period can correspond to the magnitude drop of the positive sequence component of the grid connection point voltage.

[0259] 1) Feasible region of grid connection point voltage

[0260] The virtual synchronous control device can determine the first candidate maximum power limit value P according to the grid connection point reactive power measurement value and the grid connection point voltage measurement value. lim,max,us,puand the first candidate minimum power limit value P lim,min,us,pu .

[0261] For example, the virtual synchronous control device can determine the first candidate maximum power limit value P according to the measured value of the reactive power at the grid connection point and the measured value of the voltage at the grid connection point by the following formula (1): lim,max,us,pu .

[0262]

[0263] Among them, u s,pu Represents the per-unit value of the grid-connected point voltage measurement value, i s,lim,pu Represents the preset current limit value, Q pu Represents the per-unit value of the reactive power measurement value at the grid connection point.

[0264] Of course, the virtual synchronous control device can also determine the first candidate power maximum limit value P according to the measured value of the reactive power and the measured value of the voltage at the grid connection point by other variations or equivalent formulas of the above formula (1): lim,max,us,pu .

[0265] Furthermore, the virtual synchronization control device may determine the first candidate minimum power limit value Plim,min,us,pu according to the first candidate maximum power limit value Plim,max,us,pu.

[0266] For example, the virtual synchronization control device is configured to generate a first candidate maximum power limit value P lim,max,us,pu The first candidate minimum power limit value P can be determined by the following formula (2): lim,min,us,pu .

[0267] P lim,min,us,pu = -P lim,max,us,pu Formula (2)

[0268] Of course, the virtual synchronization control device is based on the first candidate maximum power limit value P lim,max,us,pu The first candidate minimum power limit value P can also be determined by other variations or equivalent formulas of the above formula (2): lim,min,us,pu .

[0269] 2) Amplitude drop of the positive sequence component of the grid connection point voltage

[0270] Since the positive sequence component amplitude of the grid connection point voltage is positively correlated with the active power, the virtual synchronous control device can determine the second candidate power maximum limit value P according to the drop amplitude of the grid point voltage measurement value during the fault period. lim,max,ud1,pu and the second candidate minimum power limit value P lim,min,ud1,pu .

[0271] For example, the virtual synchronous control device can determine the second candidate maximum power limit value P according to the drop amplitude of the grid voltage measurement value during the fault period by the following formula (3): lim,max,ud1,pu .

[0272] P lim,max,ud1,pu =u record Formula (3)

[0273] Among them, u record Represents the drop in the measured voltage at the network point during a fault.

[0274] Of course, the virtual synchronous control device can also determine the second candidate maximum power limit value P according to the drop amplitude of the network point voltage measurement value during the fault period through other variations or equivalent formulas of the above formula (3): lim,max,ud1,pu .

[0275] Furthermore, the virtual synchronization control device can be configured to determine the maximum power limit value P of the second candidate power source according to the second candidate power maximum limit value P. lim,max,ud1,pu Determine the second candidate minimum power limit value P lim,min,ud1,pu .

[0276] For example, the virtual synchronization control device is configured to control the second candidate maximum power limit value P lim,max,ud1,pu The second candidate minimum power limit value P can be determined by the following formula (4): lim,min,ud1,pu .

[0277] P lim,min, ud1,pu = -P lim,max,ud1,pu Formula (4)

[0278] Of course, the virtual synchronization control device is based on the second candidate maximum power limit value P lim,max,ud1,pu The second candidate minimum power limit value P can also be determined by other variations or equivalent formulas of the above formula (4): lim,min,ud1,pu .

[0279] 3) Determine the target power limit value based on the candidate power limit value

[0280] The virtual synchronization control device can set the first candidate maximum power limit value P lim,max,us,pu and the second candidate maximum power limit value P lim,max,ud1,pu The minimum value among them is taken as the target power maximum limit value P lim,max,pu , and the first candidate minimum power limit value P lim,min,us,pu and the second candidate minimum power limit value P lim,min,ud1,pu The maximum value among them is taken as the target power minimum limit value P lim,min,pu .

[0281] Of course, the virtual synchronous control device can also determine the target power maximum limit value P by other means. lim,max,pu and the target power minimum limit value P lim,min,pu .

[0282] In another possible implementation, the virtual synchronization control device detects the grid connection point fault detection signal f sig It is used to indicate that if the fault is cleared within the first preset time, the maximum active power limit value P lim,max The target power maximum limit value P lim,max,pu Adjust to the preset maximum power limit value and the minimum active power limit value P lim,min The target power minimum limit value P lim,min,pu Adjust to the preset minimum power limit value.

[0283] For example, the virtual synchronous control device may set the maximum active power limit value P to lim,max The target power maximum limit value P lim,max,pu Adjust to the preset maximum power limit value, and adjust the active power minimum limit value P according to the second preset rate lim,min The target power minimum limit value P lim,min,pu Adjust to the preset minimum power limit value.

[0284] For ease of understanding, the overall process of the active power limit value adjustment method is exemplarily introduced in the following embodiments of the present application. Figure 10 is a flow chart of the active power limit value adjustment method provided by some embodiments of the present application. As shown in Figure 10, the method of the embodiment of the present application may include the following steps:

[0285] Step S1001: In the initial state, the virtual synchronous control device can set the maximum active power limit value P lim,max Set to the preset maximum power limit value and the minimum active power limit value P lim,min Set to the preset minimum power limit value.

[0286] Step S1002: The virtual synchronization control device can detect the grid fault detection signal f sig Whether it is the first preset signal.

[0287] If the grid connection point fault detection signal f is detected sig is the first preset signal, i.e., based on the grid fault detection signal f sig If a fault in the energy storage system is detected, step S1003 is executed; if a grid connection point fault detection signal f is detected, sig If it is not the first preset signal, that is, it is detected that the energy storage system has no fault according to the grid connection point fault detection signal fsig, the process returns to step S1002.

[0288] Step S1003: The virtual synchronous control device sets the maximum active power limit value P lim,max Adjust to the target power maximum limit value P lim,max,pu , and the minimum active power limit value P lim,min Adjust to the target power minimum limit value P lim,min,pu .

[0289] Step S1004: The virtual synchronization control device can detect the grid fault detection signal f sig Is it the second preset signal, and the grid fault detection signal change Δf sig Is it less than 0?

[0290] If the fault detection signal f sig is the second preset signal, and the grid fault detection signal change Δf sig Less than 0, that is, the grid connection point fault detection signal f is detected sig It is used to indicate that the fault is cleared within the first preset time, then step S1005 is executed; if the grid fault detection signal f is detected sig Not the second preset signal, or the grid fault detection signal change Δf sig Not less than 0, that is, the grid connection point fault detection signal f is detected sig It is used to indicate that the fault is not cleared within the first preset time period, and then the process returns to step S1004.

[0291] Step S1005: The virtual synchronous control device can set the maximum active power limit value P lim,max The target power maximum limit value P lim,max,pu Adjust to the preset maximum power limit value and the minimum active power limit value P lim,min The target power minimum limit value P lim,min,pu Adjust to the preset minimum power limit value.

[0292] In summary, in the embodiments of the present application, by adjusting the target power maximum limit value and the target power minimum limit value according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value and the drop amplitude of the grid connection point voltage measurement value during the fault period, the active power reference value of the energy storage system during the fault period can be made not to exceed the actual capacity of the system, thereby alleviating the problem that the active power input is always greater than zero, causing the work angle to continue to increase, and ultimately leading to periodic changes in the grid connection point voltage and large swings in the active power, thereby improving the transient stability of the energy storage system during the fault period.

[0293] In some embodiments, based on the above embodiments, the adjustment process of the damping coefficient and the latching coefficient is exemplarily introduced and explained in the embodiments of the present application.

[0294] Considering that it is necessary to further prevent the power angle movement during the fault period to prevent the periodic fluctuation of the grid voltage and alleviate the problem of power angle swing after the fault is restored, the core solution proposed in the embodiment of the present application is to make ΔP pu =P ref,pu -P pu The absolute value of is as small as possible. The following two methods can be used: 1. Adaptively increase the damping coefficient D; 2. Adaptively adjust the latch coefficient to adjust the integral link of the active frequency.

[0295] In the embodiment of the present application, the virtual synchronous control device of the energy storage system can also adjust the damping coefficient D and the latching coefficient f according to the grid fault detection signal. SH .

[0296] In a possible implementation, the virtual synchronization control device detects a grid connection point fault detection signal f sig When the energy storage system fails, the damping coefficient D can be adjusted to the target damping coefficient D. f , and the latch coefficient f SH Adjust to the target latch coefficient. For example, the target latch coefficient can be zero. Correspondingly, the integral link of the first integral process shown in FIG6C can be expressed as the following formula (5).

[0297]

[0298] It should be understood that when the energy storage system has no faults, the damping coefficient D can be the preset damping coefficient D0, and the latching coefficient f SH It can be a preset latch coefficient. For example, the preset latch coefficient can be 1. Correspondingly, the integration link of the first integration process shown in FIG6C can be expressed as the following formula (6).

[0299]

[0300] The target damping coefficient D in the embodiment of the present application f It can be related to the offset of the active power at the grid connection point during the fault and the allowable frequency offset during the fault.

[0301] For example, the virtual synchronous control device can determine the target damping coefficient D according to the offset ΔP of the active power of the grid connection point during the fault period and the allowable frequency offset Δf during the fault period by the following formula (7): f .

[0302]

[0303] Among them, f b Represents the frequency reference value, which is generally 50Hz; S bRepresents the AC power reference value; P ref,pu Represents the per-unit value of the active power reference value at the grid connection point.

[0304] Of course, the virtual synchronous control device can also determine the target damping coefficient D by other variations or equivalent formulas of the above formula (7) based on the offset ΔP of the active power of the grid connection point during the fault period and the allowable frequency offset Δf during the fault period. f .

[0305] In another possible implementation, the virtual synchronization control device detects the grid connection point fault detection signal f sig It is used to indicate that if the fault is cleared within the second preset time, the damping coefficient D can be changed from the target damping coefficient D f Adjust to the preset damping coefficient D0 and the latch coefficient f SH The target latch coefficient is adjusted to the preset latch coefficient.

[0306] For example, the virtual synchronous control device may change the damping coefficient D from the target damping coefficient D to the target damping coefficient D according to a third preset rate. f Adjust to the preset damping coefficient D0 to solve the power angle swing problem after fault recovery.

[0307] For ease of understanding, the damping coefficient D and the latching coefficient f are given in the following embodiments of the present application. SH FIG11 is a flow chart of a method for adjusting the damping coefficient and the latching coefficient provided in some embodiments of the present application. As shown in FIG11 , the method of the embodiment of the present application may include the following steps:

[0308] Step S1101: In the initial state, the virtual synchronous control device can set the damping coefficient D to the preset damping coefficient D0 and the latch coefficient f SH Set to the preset latch coefficient.

[0309] Step S1102: The virtual synchronization control device can detect the grid fault detection signal f sig Whether it is the first preset signal.

[0310] If the grid connection point fault detection signal f is detected sig is the first preset signal, i.e., based on the grid fault detection signal f sig If a fault in the energy storage system is detected, step S1103 is executed; if a grid connection point fault detection signal f is detected, sig It is not the first preset signal, that is, according to the grid fault detection signal f sig If it is detected that the energy storage system has no fault, the process returns to step S1102 .

[0311] Step S1103: The virtual synchronous control device adjusts the damping coefficient D to the target damping coefficient D. f , and the latch coefficient f SH Adjust to target latch factor.

[0312] Step S1104: The virtual synchronization control device can detect the grid fault detection signal f sig Is it the second preset signal, and the grid fault detection signal change Δf sig Is it less than 0?

[0313] If the fault detection signal f sig is the second preset signal, and the grid fault detection signal change Δf sig Less than 0, that is, the grid connection point fault detection signal f is detected sig It is used to indicate that the fault is cleared within the second preset time, then step S1105 is executed; if the grid fault detection signal f is detected, sig Not the second preset signal, or the grid fault detection signal change Δf sig Not less than 0, that is, the grid connection point fault detection signal f is detected sig It is used to indicate that the fault is not cleared within the second preset time period, and then the process returns to step S1104.

[0314] Step S1105: The virtual synchronous control device can change the damping coefficient D from the target damping coefficient D f Adjust to the preset damping coefficient D0 and the latch coefficient f SH The target latch coefficient is adjusted to the preset latch coefficient.

[0315] In summary, in the embodiments of the present application, by adaptively adjusting the damping coefficient and the latching coefficient to adjust the integral link of the active frequency, the power angle movement during the fault period can be further reduced, so that the absolute value of the active power deviation is as small as possible, thereby alleviating the large power angle swing after the fault is recovered and the problem of continuous periodic fluctuation of the grid voltage, thereby improving the transient stability of the energy storage system during the fault recovery process.

[0316] In some embodiments, based on the above embodiments, the process of determining the above-mentioned grid connection point fault detection signal is exemplarily introduced and explained in the embodiments of the present application.

[0317] In the embodiment of the present application, the virtual synchronous control device of the energy storage system can also determine the grid connection point fault detection signal based on the grid connection point voltage measurement value, the preset fault detection threshold and the preset fault clearing threshold. For example, the grid connection point voltage measurement value may include but is not limited to the second axis voltage measurement component. For example, the second axis voltage measurement component can be the d-axis component measurement value u of the grid connection point voltage in the dq coordinate system. d1,pu.

[0318] Illustratively, in an embodiment of the present application, the virtual synchronization control device determines a grid connection point fault detection signal by comparing a grid connection point voltage measurement value with a preset fault detection threshold and a preset fault clearing threshold.

[0319] In one possible implementation, the virtual synchronous control device detects that the change value of the grid connection point voltage measurement value is less than 0, and the grid connection point voltage measurement value is less than or equal to the preset fault detection threshold fault within a third preset time period. thd In the case of the fault detection signal f, the grid connection point can be determined sig It is used to indicate that the energy storage system has failed and record the drop in the voltage measurement value at the grid connection point during the fault period. record , where the drop amplitude u record It can be equal to the measured value of the grid connection point voltage. It should be understood that when the energy storage system has no fault, the drop amplitude u record The preset drop amplitude may be, for example, a preset drop amplitude including but not limited to 1 pu.

[0320] In another possible implementation, the virtual synchronization control device detects that the change value of the grid connection point voltage measurement value is greater than 0 and the grid connection point voltage measurement value is greater than or equal to the preset fault clearing threshold value. thd In the case of the fault detection signal f, the grid connection point can be determined sig It is used to indicate that the energy storage system has cleared the fault within the fourth preset time period and to calculate the drop amplitude of the grid connection point voltage measurement value during the fault period u record Adjust to the preset drop value.

[0321] For ease of understanding, the overall process of the method for determining a grid connection point fault detection signal is exemplarily described in the following embodiments of the present application. Figure 12 is a flow chart of the method for determining a grid connection point fault detection signal provided by some embodiments of the present application. As shown in Figure 12, the method of the embodiment of the present application may include the following steps:

[0322] Step S1201: In the initial state, the virtual synchronization control device can detect the fault of the grid point. sig Set as the second preset signal.

[0323] Step S1202: The virtual synchronous control device can detect the change value Δu of the grid connection point voltage measurement value. d1,pu Is it less than 0, and the grid voltage measurement value u d1,pu Is it less than or equal to the preset fault detection threshold fault thd .

[0324] If the change value Δu of the grid connection point voltage measurement value is detected d1,puLess than 0, and the grid voltage measurement value u d1,pu Less than or equal to the preset fault detection threshold fault thd , then execute step S1203; if the change value Δu of the grid point voltage measurement value is detected d1,pu Not less than 0, or the grid voltage measurement value u d1,pu Greater than the preset fault detection threshold fault thd , then execute step S1204.

[0325] Step S1203: The virtual synchronization control device may wait for a third preset time t wait , and detect the grid voltage measurement value u d1,pu Is it less than or equal to the preset fault detection threshold fault thd Among them, the third preset time length t wait It may include but is not limited to 5ms.

[0326] If the voltage measurement value u of the grid connection point is detected d1,pu Less than or equal to the preset fault detection threshold fault thd , then execute step S1205; if the grid point voltage measurement value u is detected d1,pu Greater than the preset fault detection threshold fault thd , then return to step S1202.

[0327] Step S1204: The virtual synchronization control device can detect the fault of the grid point. sig Continue to set it as the second preset signal and set the drop amplitude u record Set to the preset drop value.

[0328] Step S1205: The virtual synchronization control device can detect the fault of the grid point. sig Adjust to the first preset signal and set the drop amplitude u record Set to the grid point voltage measurement value u d1,pu .

[0329] Step S1206: The virtual synchronous control device can detect the change value Δu of the grid point voltage measurement value. d1,pu Is it greater than 0, and the grid voltage measurement value u d1,pu Is it greater than or equal to the preset fault clearing threshold? thd .

[0330] If the change value Δu of the grid connection point voltage measurement value is detected d1,pu Greater than 0, and the grid voltage measurement value u d1,pu Greater than or equal to the preset fault clearing threshold clear thd, then execute step S1207; if the change value Δu of the grid point voltage measurement value is detected d1,pu Not greater than 0, or the grid voltage measurement value u d1,pu Less than the preset fault clearing threshold clear thd , then return to step S1206.

[0331] Step S1207: The virtual synchronization control device can detect the fault of the grid point. sig Adjust to the second preset signal and set the drop amplitude u of the grid voltage measurement value during the fault period record Adjust to the preset drop value.

[0332] In summary, in the embodiments of the present application, a grid connection point fault detection signal is determined based on the grid connection point voltage measurement value, the preset fault detection threshold, and the preset fault clearing threshold, so that the active power limit value, the damping coefficient, and the latching coefficient can be adjusted according to the grid connection point fault detection signal, so that the active power reference value of the energy storage system during the fault period does not exceed the actual capacity of the system, thereby improving the transient stability of the energy storage system during the fault period.

[0333] In some embodiments, based on the above embodiments, in the embodiments of the present application, the virtual synchronization control device of the energy storage system can also perform pre-synchronization processing on the output signal of the AC side of the voltage source converter valve according to the grid connection point voltage measurement value when it detects that the energy storage system is in the initial stage of grid connection, so that the internal potential amplitude and output phase angle (or vector angle) of the voltage source converter valve can be kept the same as the amplitude and vector angle of the grid connection point voltage, respectively, so as to minimize the current impact at the grid connection moment, thereby facilitating smooth switching.

[0334] It should be noted that the virtual synchronization control device exits the pre-synchronization process after completing the pre-synchronization process.

[0335] FIG13A is a flow chart of a method for pre-synchronization processing of an output signal on the AC side of a voltage source converter valve according to some embodiments of the present application. As shown in FIG13A , the pre-synchronization processing method according to the embodiment of the present application may include the following steps:

[0336] Step S1301: Perform a second PI adjustment process on the first-axis voltage measurement component to obtain an adjusted first-axis voltage measurement component.

[0337] Illustratively, the grid connection point voltage measurement value in the embodiments of the present application may include, but is not limited to, a first-axis voltage measurement component and a second-axis voltage measurement component. For example, the first-axis voltage measurement component may be a q-axis component measurement value of the grid connection point voltage in a dq coordinate system, and the second-axis voltage measurement component may be a d-axis component measurement value of the grid connection point voltage in the dq coordinate system.

[0338] In this step, the virtual synchronous control device may perform a second PI adjustment process on the first-axis voltage measurement component to obtain an adjusted first-axis voltage measurement component.

[0339] Step S1302: Perform a second integration process on the adjusted first-axis voltage measurement component and the grid rated angular frequency to obtain an output voltage phase angle on the AC side of the voltage source converter valve; wherein the output voltage phase angle is the same as the grid connection point voltage phase angle.

[0340] Exemplarily, the grid rated angular frequency may include but is not limited to a per-unit value of the grid rated angular frequency, and / or a nominal value (or non-per-unit value) of the grid rated angular frequency.

[0341] In this step, the virtual synchronous control device can perform a second integration process on the adjusted first axis voltage measurement component and the grid rated angular frequency to obtain the output voltage phase angle of the AC side of the voltage source converter valve, so that the output voltage phase angle is the same as the grid connection point voltage phase angle.

[0342] For example, FIG13B is a flow chart of a method for determining the output voltage phase angle of the AC side of a voltage source converter valve provided in some embodiments of the present application. As shown in FIG13B , the virtual synchronous control device can standardize the first axis voltage measurement component u q1,pu The second PI adjustment process is performed to obtain the adjusted first axis voltage measurement component. Further, the virtual synchronous control device can be used to adjust the rated angular frequency per unit value ω n，pu The nominal value of the grid rated angular frequency ω n The multiplication process is performed, and the multiplication result and the adjusted first axis voltage measurement component are added. Further, the virtual synchronous control device can perform a second integration process on the addition result to obtain the output voltage phase angle of the AC side of the voltage source converter valve.

[0343] Step S1303: Perform a second closed-loop processing on the second axis voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve; wherein the second internal potential amplitude is the same as the grid connection point voltage amplitude.

[0344] In this step, the virtual synchronous control device may perform a second closed-loop processing on the second axis voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve, such that the second internal potential amplitude is equal to the grid connection point voltage amplitude. The second closed-loop processing may include, but is not limited to, a closed-loop control method based on PI regulation processing and a second internal potential control integral coefficient.

[0345] For example, FIG13C is a flow chart of a second closed-loop processing method provided in some embodiments of the present application. As shown in FIG13C , the virtual synchronous control device may determine a second feedback signal based on the historical internal potential amplitude, and sequentially perform a third PI adjustment process and a third integral process on the difference signal between the second axis voltage measurement component and the second feedback signal to obtain the second internal potential amplitude. The historical internal potential amplitude may include, but is not limited to, the result obtained by the virtual synchronous control device performing the last second closed-loop processing on the historical second axis voltage measurement component (or the second axis voltage measurement component at the previous moment).

[0346] In this embodiment of the present application, the virtual synchronous control device may use the historical internal potential amplitude as a second feedback signal and subtract the second axis voltage measurement component from the second feedback signal to obtain a difference signal. Furthermore, the virtual synchronous control device may sequentially perform a third PI adjustment process and a third integration process on the difference signal to obtain the second internal potential amplitude.

[0347] Furthermore, in order to make the second internal potential amplitude more consistent with the actual capacity of the energy storage system, in an embodiment of the present application, the virtual synchronous control device can perform a third PI adjustment process and a third integral process on the difference signal between the second axis voltage measurement component and the second feedback signal in sequence to obtain a second initial internal potential amplitude, and limit the second initial internal potential amplitude according to the maximum internal potential amplitude and the minimum internal potential amplitude to obtain a second internal potential amplitude.

[0348] For example, FIG13D is a flow chart of the second closed-loop processing method provided by some embodiments of the present application. As shown in FIG13D , the virtual synchronous control device can use the historical internal potential amplitude as the second feedback signal and the second axis voltage measurement component per unit value u d1,pu The difference signal is obtained by subtracting the second feedback signal. Further, the virtual synchronous control device can sequentially perform a third PI adjustment process on the difference signal and control the integral coefficient K according to the second internal potential. Ei2 The third integral process is performed to obtain the second initial internal potential amplitude. Further, the virtual synchronous control device can perform a limiting process on the second initial internal potential amplitude according to the maximum internal potential amplitude and the minimum internal potential amplitude to obtain the second internal potential amplitude E.

[0349] It can be seen that in the embodiment of the present application, by limiting the second initial internal potential amplitude according to the maximum internal potential amplitude and the minimum internal potential amplitude, a more accurate second internal potential amplitude can be obtained, so that the second internal potential amplitude can be made the same as the grid connection point voltage amplitude according to the second internal potential amplitude, which is beneficial to improving the pre-synchronization processing effect.

[0350] In summary, in the embodiment of the present application, the first-axis voltage measurement component is subjected to a second PI adjustment process to obtain an adjusted first-axis voltage measurement component, and the adjusted first-axis voltage measurement component and the grid rated angular frequency are subjected to a second integration process to obtain the output voltage phase angle of the AC side of the voltage source converter valve; wherein, the output voltage phase angle is the same as the grid connection point voltage phase angle. Further, the second-axis voltage measurement component is subjected to a second closed-loop process to obtain the second internal potential amplitude of the voltage source converter valve; wherein, the second internal potential amplitude is the same as the grid connection point voltage amplitude. It can be seen that in the embodiment of the present application, by performing PI adjustment and integration processing on the first-axis voltage measurement component and performing a second closed-loop process on the second-axis voltage measurement component, the internal potential amplitude and output voltage phase angle of the voltage source converter valve synchronized with the grid connection point voltage can be generated, so as to minimize the current impact at the grid connection moment, thereby facilitating smooth switching.

[0351] In some embodiments, FIG14A is a flow chart of a virtual synchronous control method for an energy storage system provided in other embodiments of the present application. Based on the above embodiments, the embodiments of the present application introduce the relevant content of "controlling the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve" in the above step S301. For example, the output electrical signal measurement value in the embodiments of the present application may include but is not limited to: the output voltage measurement value of the DC side of the voltage source converter valve and the output current measurement value of the DC side of the voltage source converter valve. As shown in FIG14A, the above step S301 may include the following steps:

[0352] Step S3011: Perform a fourth PI adjustment process on the DC voltage difference between the output voltage measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve to obtain a DC current command value.

[0353] In this step, the virtual synchronous control device can obtain a DC voltage difference by subtracting the output voltage measurement value of the DC side of the voltage source converter valve from the output voltage reference value of the DC energy storage valve, and obtain a DC current command value by performing a fourth PI adjustment process on the DC voltage difference through the PI regulator, so as to realize the DC voltage outer loop processing.

[0354] For example, FIG14B is a flow chart of a fourth PI regulation processing method provided in some embodiments of the present application. As shown in FIG14B , the virtual synchronous control device can standardize the output voltage measurement value of the DC side of the voltage source converter valve to a per-unit value e dc,pu The output voltage reference value per unit value u of the DC energy storage valve dc,ref,pu The DC voltage difference is obtained by subtracting the difference. p,udcAs the DC voltage control proportional coefficient and K i,udc As the DC voltage control integral coefficient, the DC voltage difference is subjected to the fourth PI adjustment process to obtain the DC current command value per unit value i dc,cmd,pu .

[0355] To ensure that the output voltage of the DC energy storage valve more closely matches the actual capacity of the energy storage system, the virtual synchronous control device may perform a fourth PI adjustment on the DC voltage difference between the measured output voltage of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve to obtain an initial DC current reference value. The initial DC current reference value is then clipped based on the maximum and minimum DC current amplitudes to obtain a DC current command value. The maximum DC current amplitude refers to the maximum output voltage amplitude of the DC energy storage valve, and the minimum DC current amplitude refers to the minimum output voltage amplitude of the DC energy storage valve.

[0356] For example, if the initial DC current command value is greater than the maximum DC current amplitude, the virtual synchronous control device may use the maximum DC current amplitude as the DC current command value.

[0357] In another exemplary embodiment, if the initial DC current command value is less than or equal to the maximum DC current amplitude and greater than or equal to the minimum DC current amplitude, the virtual synchronous control device may use the initial DC current command value as the DC current command value.

[0358] As another example, if the initial DC current command value is smaller than the minimum DC current amplitude, the virtual synchronous control device may use the minimum DC current amplitude as the DC current command value.

[0359] It can be seen that in the embodiment of the present application, by limiting the initial DC current command value according to the maximum DC current amplitude and the minimum DC current amplitude, a more accurate DC current command value can be obtained, so that a more accurate output voltage command value of the DC energy storage valve can be obtained according to the DC current command value, thereby more accurately controlling the output voltage of the DC energy storage valve.

[0360] Step S3012: Perform a fifth PI adjustment process on the DC current difference between the output current measurement value of the DC side of the voltage source converter valve and the DC current command value to obtain an output voltage command value of the DC energy storage valve.

[0361] In this step, the virtual synchronous control device can subtract the output current measurement value of the DC side of the voltage source converter valve from the DC current command value to obtain a DC current difference, and perform a fifth PI adjustment process on the DC current difference through the PI regulator to obtain the output voltage command value of the DC energy storage valve, so as to realize the DC current inner loop processing.

[0362] For example, FIG14C is a flowchart of a fifth PI regulation processing method provided in some embodiments of the present application. As shown in FIG14C , the virtual synchronous control device can standardize the output current measurement value of the DC side of the voltage source converter valve to a per-unit value i dc,pu The DC current command value per unit value i dc,cmd,pu The DC current difference is obtained by subtracting the difference. p,idc As the DC current control proportional coefficient and K i,idc As the DC current control integral coefficient, the DC current difference is subjected to the fifth PI adjustment process to obtain the output voltage command value per unit value u of the DC energy storage valve dc,cmd,pu .

[0363] To ensure that the output voltage of the DC energy storage valve more closely matches the actual capacity of the energy storage system, the virtual synchronous control device can perform a fifth PI adjustment on the DC current difference between the measured output current value on the DC side of the voltage source converter valve and the DC current command value to obtain an initial output voltage command value. The initial output voltage command value is then clipped based on the maximum and minimum DC voltage amplitudes to obtain an output voltage command value. The maximum DC voltage amplitude refers to the maximum output voltage amplitude of the DC energy storage valve, and the minimum DC voltage amplitude refers to the minimum output voltage amplitude of the DC energy storage valve.

[0364] For example, if the initial output voltage command value is greater than the maximum DC voltage amplitude, the virtual synchronous control device may use the maximum DC voltage amplitude as the output voltage command value.

[0365] In another exemplary embodiment, if the initial output voltage command value is less than or equal to the maximum DC voltage amplitude and greater than or equal to the minimum DC voltage amplitude, the virtual synchronous control device may use the initial output voltage command value as the output voltage command value.

[0366] In another exemplary embodiment, if the initial output voltage command value is smaller than the minimum DC voltage amplitude, the virtual synchronous control device may use the minimum DC voltage amplitude as the output voltage command value.

[0367] It can be seen that in the embodiment of the present application, by limiting the initial output voltage command value according to the maximum DC voltage amplitude and the minimum DC voltage amplitude, a more accurate output voltage command value can be obtained, so that the output voltage of the DC energy storage valve can be more accurately controlled according to the output voltage command value.

[0368] For ease of understanding, the overall process of the output voltage control method of the DC energy storage valve is introduced in the following embodiments of the present application. Figure 14D is a flow chart of the output voltage control method of the DC energy storage valve provided in some embodiments of the present application. As shown in Figure 14D, the virtual synchronous control device can standardize the output voltage measurement value of the DC side of the voltage source converter valve to the unit value e dc,pu The output voltage reference value per unit value u of the DC energy storage valve dc,ref,pu The DC voltage difference is obtained by subtracting the difference. p,udc As the DC voltage control proportional coefficient and K i,udc As the DC voltage control integral coefficient, the DC voltage difference is subjected to the fourth PI adjustment process to obtain the initial DC current reference value, and the initial DC current reference value is subjected to DC current limiting process according to the DC current maximum amplitude and the DC current minimum amplitude to obtain the DC current command value per unit value i dc,cmd,pu .

[0369] Furthermore, the virtual synchronous control device can standardize the output current measurement value of the DC side of the voltage source converter valve to the unit value i dc,pu The DC current command value per unit value i dc,cmd,pu The DC current difference is obtained by subtracting the difference. p,idc As the DC current control proportional coefficient and K i,idc As the DC current control integral coefficient, the DC current difference is subjected to the fifth PI adjustment process to obtain the initial output voltage command value, and the initial output voltage command value is subjected to DC voltage limiting process according to the maximum DC voltage amplitude and the minimum DC voltage amplitude to obtain the output voltage command value command value per unit value u dc,cmd,pu .

[0370] Step S3013: controlling the output voltage of the DC energy storage valve according to the output voltage command value of the DC energy storage valve.

[0371] In this step, the virtual synchronous control device may generate a second control signal according to the output voltage command value of the DC energy storage valve, wherein the second control signal is used to control the output voltage of the DC energy storage valve to achieve independent control of the output voltage of the DC energy storage valve.

[0372] In summary, in the embodiments of the present application, a DC current command value is obtained by performing a fourth PI adjustment process on the DC voltage difference between the output voltage measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve. Furthermore, a fifth PI adjustment process is performed on the DC current difference between the output current measurement value of the DC side of the voltage source converter valve and the DC current command value to obtain the output voltage command value of the DC energy storage valve, and the output voltage of the DC energy storage valve is controlled based on the output voltage command value of the DC energy storage valve. It can be seen that in the embodiments of the present application, independent control of the output voltage of the DC energy storage valve is achieved based on the output voltage measurement value and output current measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve. This eliminates the need for the voltage source converter valve to take into account both DC and AC side control. This simplifies the complexity of the control loop of the voltage source converter valve and improves the dynamic control performance of the output voltage of the DC energy storage valve, thereby achieving grid-type control of the energy storage system and providing effective inertia support and voltage support for the power grid.

[0373] In some embodiments, FIG15 is a schematic diagram of a virtual synchronous control framework of an energy storage system provided in other embodiments of the present application. Based on the above embodiments, the overall block diagram of the virtual synchronous control of the energy storage system in the embodiments of the present application is exemplarily introduced and explained.

[0374] As shown in Figure 15 , 1) the control chain of the DC energy storage valve may include, but is not limited to, a DC voltage and current sampling unit, a DC voltage outer loop control unit, a DC current inner loop control unit, and a pulse generation unit. The DC voltage outer loop control unit and the DC current inner loop control unit are core control units. Their specific implementations can be found in the relevant sections of the aforementioned method embodiments and will not be further elaborated here.

[0375] 2) The control chain of the voltage source converter valve may include, but is not limited to: an AC voltage and current sampling unit, an AC voltage and current coordinate transformation unit, a grid connection point power and voltage amplitude calculation unit (or simply a power and amplitude calculation unit), a fault detection unit, a VSG active and reactive power decoupling control unit (or simply a VSG control unit), a voltage outer loop control unit, a current limiting unit, a current inner loop control unit, and a pulse generation unit. The fault detection unit, the VSG active and reactive power decoupling control unit, the voltage outer loop control unit, and the current inner loop control unit are core control units. Their specific implementation can be found in the relevant content of the above-mentioned method embodiments and will not be further described here.

[0376] It should be understood that the AC voltage and current coordinate transformation unit may include but is not limited to T abc-dq Transformation unit (or Parker transform unit) and T dq-abc Transformation unit.

[0377] Part of the parameters in FIG15 can be referred to as shown in Table 2.

[0378] Table 2 is a schematic table of some parameters in Figure 15

[0379] It should be noted that, when the voltage source converter valve 101 can be directly connected to the AC power grid 104 without passing through the transformer 105, the AC side of the voltage source converter valve in the embodiment of the present application does not need to be distinguished between the AC network side of the voltage source converter valve and the AC valve side of the voltage source converter valve, or in other words, the AC network side of the voltage source converter valve and the AC valve side of the voltage source converter valve are the same.

[0380] In summary, in the embodiments of the present application, the high-voltage direct current (HVDC) energy storage system is divided into two parts: a voltage source converter valve and a DC energy storage valve, which are independently controlled. By adopting a DC voltage-DC current dual closed-loop control for the DC energy storage valve, the DC side voltage of the voltage source converter valve is kept constant, thereby supporting the operation of the voltage source converter valve in a virtual synchronous control mode. Furthermore, by adopting a virtual synchronous control for the voltage source converter valve that decouples active power from reactive power, transient support for the grid connection point frequency and grid connection point voltage is achieved. Furthermore, by coordinating the damping parameters with the power limit value, the problem of large power angle swing and continuous periodic fluctuation of the grid connection point voltage after fault recovery can be solved, which is beneficial to improving the transient stability of the system during faults and during fault recovery, thereby achieving reliable low-voltage fault ride-through of the energy storage system.

[0381] FIG16A shows the active power P of the grid connection point, the reactive power Q of the grid connection point, and the AC grid voltage amplitude U provided in an embodiment of the present application. s 16B is a schematic diagram of the simulation results, FIG16B is an output voltage u of the DC energy storage valve provided in the embodiment of the present application dc , the output current i of the DC side of the voltage source converter valve dc The simulation results for the output frequency ω of the AC side of the voltage source converter valve are shown in Figures 16A and 16B. The simulation results for a single-phase grid-side fault show that the energy storage system experiences a full active power step at time 1s; the energy storage system fails at time 2.5s; and the energy storage system fault is cleared at time 3s. Time-domain simulations verify that the virtual synchronous control method for the energy storage system provided in this embodiment of the application has both inertia support and grid voltage support capabilities, and can meet the grid-connection specification requirements for the low-voltage fault ride-through capability of the energy storage system.

[0382] It should be understood that, although the steps in the flowcharts of the above embodiments are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be performed in other orders. Moreover, at least a portion of the steps in the flowcharts of the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily to be performed in sequence, but can be performed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0383] Based on the same inventive concept, embodiments of the present application also provide a virtual synchronization control device for implementing the aforementioned virtual synchronization control method for an energy storage system. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of the embodiments of the virtual synchronization control device for one or more energy storage systems provided below can be found in the aforementioned limitations of the virtual synchronization control method for an energy storage system, and will not be further elaborated here.

[0384] In some embodiments, Figure 17 is a schematic diagram of the structure of a virtual synchronization control device for an energy storage system provided in some embodiments of the present application. The virtual synchronization control device for an energy storage system provided in embodiments of the present application can be applied to a control device of the energy storage system. As shown in Figure 17, the virtual synchronization control device for an energy storage system in embodiments of the present application may include: a first control module 1701 and a second control module 1702.

[0385] The first control module 1701 is configured to control the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve;

[0386] The second control module 1702 is configured to control the output signal of the AC side of the voltage source converter valve according to the measured value of the grid connection point electrical signal of the voltage source converter valve and the reference value of the grid connection point electrical signal.

[0387] In some embodiments, the grid point electrical signal measurement value includes: a grid point active power measurement value, a grid point reactive power measurement value, and a grid point voltage measurement value; the grid point electrical signal reference value includes: a grid point active power reference value, a grid point reactive power reference value, and a grid point voltage reference value; and the second control module 1702 includes:

[0388] A first control unit is configured to control the output frequency of the AC side of the voltage source converter valve according to the measured active power value of the grid connection point and the active power reference value of the grid connection point;

[0389] The second control unit is used to control the output voltage amplitude of the AC side of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value.

[0390] In some embodiments, the first control unit includes:

[0391] A first determining subunit, configured to determine a grid connection point active power deviation based on a grid connection point active power measurement value and a grid connection point active power reference value;

[0392] A closed-loop control subunit, configured to perform a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result;

[0393] The first control subunit is used to control the output frequency according to the closed-loop result and the rated angular frequency of the power grid.

[0394] In some embodiments, the first determining subunit is specifically configured to:

[0395] The active power reference value of the grid connection point is limited according to the maximum active power limit value and the minimum active power limit value to obtain the active power reference value of the grid connection point after limiting;

[0396] The active power deviation of the grid connection point is obtained by subtracting the active power reference value of the grid connection point after limiting from the active power measurement value of the grid connection point.

[0397] In some embodiments, the closed-loop control subunit is specifically configured to:

[0398] Determining a first feedback signal based on historical closed-loop results and a damping coefficient;

[0399] A first integration process is performed on a difference signal between the active power deviation of the grid connection point and the first feedback signal to obtain a closed-loop result.

[0400] In some embodiments, the closed-loop control subunit is specifically configured to:

[0401] A first integration process is performed on the difference signal according to the inertia time constant and the latch coefficient to obtain a closed-loop result.

[0402] In some embodiments, the virtual synchronization control device of the energy storage system further includes:

[0403] The first adjustment module is used to adjust the maximum active power limit value and the minimum active power limit value according to the grid connection point fault detection signal.

[0404] In some embodiments, the first adjustment module is specifically configured to:

[0405] When a grid connection point fault detection signal is detected indicating that a fault has occurred in the energy storage system, the maximum active power limit value is adjusted to the target maximum power limit value, and the minimum active power limit value is adjusted to the target minimum power limit value; or

[0406] When a grid connection point fault detection signal is detected to indicate that the fault is cleared within a first preset time period, the maximum active power limit value is adjusted from the target power maximum limit value to the preset power maximum limit value, and the minimum active power limit value is adjusted from the target power minimum limit value to the preset power minimum limit value.

[0407] In some embodiments, the virtual synchronization control device of the energy storage system further includes:

[0408] The second adjustment module is used to adjust the damping coefficient and the latching coefficient according to the grid connection point fault detection signal.

[0409] In some embodiments, the second adjustment module is specifically configured to:

[0410] When a grid connection point fault detection signal is detected indicating that a fault has occurred in the energy storage system, the damping coefficient is adjusted to a target damping coefficient, and the latching coefficient is adjusted to a target latching coefficient; or

[0411] When it is detected that the grid connection point fault detection signal indicates that the fault is cleared within the second preset time period, the damping coefficient is adjusted from the target damping coefficient to the preset damping coefficient, and the latching coefficient is adjusted from the target latching coefficient to the preset latching coefficient.

[0412] In some embodiments, the virtual synchronization control device of the energy storage system further includes:

[0413] The first determination module is used to determine a grid connection point fault detection signal according to a grid connection point voltage measurement value, a preset fault detection threshold, and a preset fault clearing threshold.

[0414] In some embodiments, the first determining module is specifically configured to:

[0415] Upon detecting that a change in the grid connection point voltage measurement value is less than 0, and the grid connection point voltage measurement value is less than or equal to a preset fault detection threshold value within a third preset time period, determining that a grid connection point fault detection signal is used to indicate that a fault has occurred in the energy storage system, and recording a drop in the grid connection point voltage measurement value during the fault period;

[0416] When it is detected that the change value of the grid connection point voltage measurement value is greater than 0, and the grid connection point voltage measurement value is greater than or equal to the preset fault clearing threshold, it is determined that the grid connection point fault detection signal is used to indicate that the energy storage system fault is cleared within a fourth preset time period, and the drop amplitude of the grid connection point voltage measurement value during the fault period is adjusted to the preset drop amplitude.

[0417] In some embodiments, the second control unit includes:

[0418] a second determining subunit, configured to determine a first internal potential amplitude of the voltage source converter valve according to a measured reactive power value at the grid connection point, a measured voltage value at the grid connection point, a reference reactive power value at the grid connection point, and a reference voltage value at the grid connection point;

[0419] The second control subunit is used to control the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude of the voltage source converter valve.

[0420] In some embodiments, the second determining subunit is specifically configured to:

[0421] Determine the reactive power deviation of the grid connection point based on the reactive power measurement value of the grid connection point and the reactive power reference value of the grid connection point;

[0422] Determine the grid connection point voltage deviation based on the grid connection point voltage measurement value and the grid connection point voltage reference value;

[0423] A second integration process is performed based on the reactive power deviation at the grid connection point and / or the voltage deviation at the grid connection point to obtain a first internal potential amplitude.

[0424] In some embodiments, the second control subunit is specifically configured to:

[0425] Performing voltage outer loop control processing according to the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop;

[0426] Perform current limiting inner loop processing according to the current command value to obtain the output voltage signal of the AC side of the voltage source converter valve;

[0427] According to the output voltage signal of the AC side of the voltage source converter valve, the output voltage amplitude of the AC side of the voltage source converter valve is controlled.

[0428] In some embodiments, the second control subunit is specifically configured to:

[0429] A first PI adjustment process, a dynamic virtual impedance process or a static virtual impedance process is performed on the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop.

[0430] In some embodiments, the virtual synchronization control device of the energy storage system further includes:

[0431] The pre-synchronization module is used to pre-synchronize the output signal of the AC side of the voltage source converter valve according to the voltage measurement value of the grid connection point when it is detected that the energy storage system is in the initial stage of grid connection.

[0432] In some embodiments, the grid connection point voltage measurement value includes a first axis voltage measurement component and a second axis voltage measurement component, and the pre-synchronization module includes:

[0433] a first regulating unit, configured to perform a second PI regulation process on the first shaft voltage measurement component to obtain an regulated first shaft voltage measurement component;

[0434] an integration unit, configured to perform a second integration process on the adjusted first axis voltage measurement component and the grid rated angular frequency to obtain an output voltage phase angle on the AC side of the voltage source converter valve; wherein the output voltage phase angle is the same as the grid connection point voltage phase angle;

[0435] The closed-loop unit is used to perform a second closed-loop processing on the second axis voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve; wherein the second internal potential amplitude is the same as the grid connection point voltage amplitude.

[0436] In some embodiments, the closed-loop unit includes:

[0437] a third determining subunit, configured to determine a second feedback signal according to the historical internal potential amplitude;

[0438] The fourth determining subunit is configured to sequentially perform a third PI adjustment process and a third integration process on a difference signal between the second axis voltage measurement component and the second feedback signal to obtain a second internal potential amplitude.

[0439] In some embodiments, the output electrical signal measurement value includes: an output voltage measurement value of the DC side of the voltage source converter valve and an output current measurement value of the DC side of the voltage source converter valve. The first control module 1701 includes:

[0440] a second regulating unit, configured to perform a fourth PI regulation process on a DC voltage difference between a measured output voltage value of the DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve to obtain a DC current command value;

[0441] a third regulating unit, configured to perform a fifth PI regulation process on a DC current difference between an output current measurement value of the DC side of the voltage source converter valve and a DC current command value, to obtain an output voltage command value of the DC energy storage valve;

[0442] The third control unit is used to control the output voltage of the DC energy storage valve according to the output voltage command value of the DC energy storage valve.

[0443] The virtual synchronization control device for an energy storage system provided in the embodiment of the present application can be used to execute the technical solution in the embodiment of the virtual synchronization control method for an energy storage system described above. The implementation principle and technical effects thereof are similar and will not be described in detail here.

[0444] Each module in the aforementioned virtual synchronous control device for an energy storage system can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor within the energy storage system's control device in hardware form, or stored in memory within the energy storage system's control device in software form, allowing the processor to call and execute the corresponding operations of each module.

[0445] In some embodiments, Figure 18 is a structural diagram of the control device of the energy storage system in some embodiments of the present application. As shown in Figure 18, the control device of the energy storage system provided in the embodiment of the present application may include a processor, a memory, a communication interface and an input device connected through a system bus. Among them, the processor of the control device is used to provide computing and control capabilities. The memory of the control device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The communication interface of the control device is used to communicate with external devices in a wired or wireless manner. The wireless manner can be achieved through WIFI, mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, it implements the technical solution in the embodiment of the virtual synchronous control method of the energy storage system mentioned above in the present application. Its implementation principle and technical effect are similar and will not be repeated here.

[0446] Exemplarily, the input device of the control device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the control device, or an external keyboard, touchpad or mouse.

[0447] Those skilled in the art will understand that the structure shown in Figure 18 is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the control device to which the scheme of the present application is applied. The specific control device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0448] In some embodiments, a control device for an energy storage system is also provided, including a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the technical solution in the embodiment of the virtual synchronous control method for the energy storage system described above in this application is implemented. The implementation principle and technical effects are similar and will not be repeated here.

[0449] In some embodiments, a computer-readable storage medium is further provided, on which a computer program is stored. When the computer program is executed by a processor, the technical solution in the embodiment of the virtual synchronous control method of the energy storage system mentioned above in this application is implemented. The implementation principle and technical effect are similar and will not be repeated here.

[0450] In some embodiments, a computer program product is also provided, including a computer program. When the computer program is executed by a processor, the technical solution in the virtual synchronization control method embodiment of the energy storage system of the present application is implemented. The implementation principle and technical effect are similar and will not be repeated here.

[0451] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. For purposes of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The processors involved in the various embodiments provided herein may be general-purpose processors, central processing units (CPUs), graphics processors (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like, without limitation thereto.

[0452] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A virtual synchronization control method for an energy storage system, wherein: The energy storage system includes a voltage source converter valve and a DC energy storage valve, and the method includes: Controlling the output voltage of the DC energy storage valve according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve; The output signal of the AC side of the voltage source converter valve is controlled according to the measured value of the grid-connected point electrical signal of the voltage source converter valve and the reference value of the grid-connected point electrical signal.

2. The method according to claim 1, wherein: The grid connection point electrical signal measurement value includes: grid connection point active power measurement value, grid connection point reactive power measurement value and grid connection point voltage measurement value; the grid connection point electrical signal reference value includes: grid connection point active power reference value, grid connection point reactive power reference value and grid connection point voltage reference value; the output signal of the AC side of the voltage source converter valve is controlled according to the grid connection point electrical signal measurement value and the grid connection point electrical signal reference value of the voltage source converter valve, including: Controlling the output frequency of the AC side of the voltage source converter valve according to the grid connection point active power measurement value and the grid connection point active power reference value; The output voltage amplitude of the AC side of the voltage source converter valve is controlled according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value.

3. The method according to claim 2, wherein: The controlling the output frequency of the AC side of the voltage source converter valve according to the grid connection point active power measurement value and the grid connection point active power reference value comprises: Determining the active power deviation of the grid connection point according to the active power measurement value of the grid connection point and the active power reference value of the grid connection point; Performing a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result; The output frequency is controlled according to the closed-loop result and the rated angular frequency of the power grid.

4. The method according to claim 3, wherein: Determining the active power deviation of the grid connection point according to the grid connection point active power measurement value and the grid connection point active power reference value includes: According to the maximum active power limit value and the minimum active power limit value, the active power reference value of the grid connection point is limited to obtain the active power reference value of the grid connection point after limiting; The grid connection point active power reference value after limiting is subtracted from the grid connection point active power measurement value to obtain the grid connection point active power deviation.

5. The method according to claim 4, wherein: The performing a first closed-loop control process on the active power deviation of the grid connection point to obtain a closed-loop result includes: Determine a first feedback signal according to historical closed-loop results and a damping coefficient; A first integration process is performed on a difference signal between the grid-connected point active power deviation and the first feedback signal to obtain the closed-loop result.

6. The method according to claim 5, wherein: The step of performing a first integration process on the difference signal between the grid connection point active power deviation and the first feedback signal to obtain the closed-loop result includes: The difference signal is subjected to a first integration process according to an inertia time constant and a latch coefficient to obtain the closed-loop result.

7. The method according to any one of claims 4 to 6, wherein: The method further comprises: The maximum active power limit value and the minimum active power limit value are adjusted according to the grid connection point fault detection signal.

8. The method according to claim 7, wherein: The adjusting the maximum active power limit value and the minimum active power limit value according to the grid connection point fault detection signal includes: When it is detected that the grid connection point fault detection signal indicates that the energy storage system has a fault, the maximum active power limit value is adjusted to the target power maximum limit value, and the minimum active power limit value is adjusted to the target power minimum limit value; or, When it is detected that the grid connection point fault detection signal is used to indicate that the fault is cleared within a first preset time period, the maximum active power limit value is adjusted from the target power maximum limit value to the preset power maximum limit value, and the minimum active power limit value is adjusted from the target power minimum limit value to the preset power minimum limit value.

9. The method according to claim 6, wherein: The method further comprises: The damping coefficient and the latching coefficient are adjusted according to the grid connection point fault detection signal.

10. The method according to claim 9, wherein: The adjusting the damping coefficient and the latching coefficient according to the grid connection point fault detection signal comprises: In the case where it is detected that the grid connection point fault detection signal is used to indicate that the energy storage system has a fault, the damping coefficient is adjusted to a target damping coefficient, and the latching coefficient is adjusted to a target latching coefficient; or, When it is detected that the grid connection point fault detection signal is used to indicate that the fault is cleared within a second preset time period, the damping coefficient is adjusted from the target damping coefficient to the preset damping coefficient, and the latching coefficient is adjusted from the target latching coefficient to the preset latching coefficient.

11. The method according to any one of claims 7 to 10, wherein: The method further comprises: The grid connection point fault detection signal is determined according to the grid connection point voltage measurement value, a preset fault detection threshold and a preset fault clearing threshold.

12. The method according to claim 11, wherein: The step of determining the grid connection point fault detection signal according to the grid connection point voltage measurement value, a preset fault detection threshold and a preset fault clearing threshold comprises: Upon detecting that the change value of the grid connection point voltage measurement value is less than 0, and the grid connection point voltage measurement value is less than or equal to the preset fault detection threshold value within a third preset time period, determining that the grid connection point fault detection signal is used to indicate that a fault has occurred in the energy storage system, and recording the drop amplitude of the grid connection point voltage measurement value during the fault period; When it is detected that the change value of the grid connection point voltage measurement value is greater than 0, and the grid connection point voltage measurement value is greater than or equal to the preset fault clearing threshold, it is determined that the grid connection point fault detection signal is used to indicate that the energy storage system fault is cleared within a fourth preset time period, and the drop amplitude of the grid connection point voltage measurement value during the fault period is adjusted to the preset drop amplitude.

13. The method according to any one of claims 2 to 12, wherein: The step of controlling the output voltage amplitude of the AC side of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value comprises: Determining a first internal potential amplitude of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value; The output voltage amplitude of the AC side of the voltage source converter valve is controlled according to the first internal potential amplitude of the voltage source converter valve.

14. The method according to claim 13, wherein: The determining the first internal potential amplitude of the voltage source converter valve according to the grid connection point reactive power measurement value, the grid connection point voltage measurement value, the grid connection point reactive power reference value and the grid connection point voltage reference value comprises: Determining the reactive power deviation of the grid connection point according to the reactive power measurement value of the grid connection point and the reactive power reference value of the grid connection point; Determining a grid connection point voltage deviation according to the grid connection point voltage measurement value and the grid connection point voltage reference value; A second integration process is performed according to the reactive power deviation of the grid connection point and / or the voltage deviation of the grid connection point to obtain the first internal potential amplitude.

15. The method according to claim 13 or 14, wherein: The step of controlling the output voltage amplitude of the AC side of the voltage source converter valve according to the first internal potential amplitude of the voltage source converter valve comprises: Performing voltage outer loop control processing according to the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop; Performing current limiting inner loop processing according to the current command value to obtain an output voltage signal of the AC side of the voltage source converter valve; According to the output voltage signal on the AC side of the voltage source converter valve, the output voltage amplitude on the AC side of the voltage source converter valve is controlled.

16. The method according to claim 15, wherein: The step of performing voltage outer loop control processing according to the first inner potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop includes: A first PI adjustment process, a dynamic virtual impedance process or a static virtual impedance process is performed on the first internal potential amplitude of the voltage source converter valve and the grid connection point voltage measurement value to obtain a current command value of the current inner loop.

17. The method according to any one of claims 2 to 16, wherein: The method further comprises: When it is detected that the energy storage system is in the initial stage of grid connection, the output signal of the AC side of the voltage source converter valve is pre-synchronized according to the measured value of the grid connection point voltage.

18. The method according to claim 17, wherein: The grid connection point voltage measurement value includes a first axis voltage measurement component and a second axis voltage measurement component, and the pre-synchronization processing of the output signal of the AC side of the voltage source converter valve according to the grid connection point voltage measurement value includes: Performing a second PI adjustment process on the first shaft voltage measurement component to obtain an adjusted first shaft voltage measurement component; Performing a second integration process on the adjusted first axis voltage measurement component and the grid rated angular frequency to obtain an output voltage phase angle on the AC side of the voltage source converter valve; wherein the output voltage phase angle is the same as the grid connection point voltage phase angle; The second shaft voltage measurement component is subjected to a second closed-loop processing to obtain a second internal potential amplitude of the voltage source converter valve; wherein the second internal potential amplitude is the same as the grid connection point voltage amplitude.

19. The method according to claim 18, wherein: The performing a second closed-loop processing on the second shaft voltage measurement component to obtain a second internal potential amplitude of the voltage source converter valve includes: determining a second feedback signal according to the historical internal potential amplitude; The difference signal between the second shaft voltage measurement component and the second feedback signal is sequentially subjected to a third PI adjustment process and a third integration process to obtain the second internal potential amplitude.

20. The method according to any one of claims 1 to 19, wherein: The output electrical signal measurement value includes: an output voltage measurement value of the DC side of the voltage source converter valve and an output current measurement value of the DC side of the voltage source converter valve. The output voltage of the DC energy storage valve is controlled according to the output electrical signal measurement value of the DC side of the voltage source converter valve and the output voltage reference value of the DC energy storage valve, including: Performing a fourth PI adjustment process on a DC voltage difference between an output voltage measurement value of the DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve to obtain a DC current command value; Performing a fifth PI adjustment process on the DC current difference between the output current measurement value of the DC side of the voltage source converter valve and the DC current command value to obtain an output voltage command value of the DC energy storage valve; The output voltage of the DC energy storage valve is controlled according to the output voltage command value of the DC energy storage valve.

21. A virtual synchronization control device for an energy storage system, wherein: The energy storage system includes a voltage source converter valve and a DC energy storage valve, and the device includes: A first control module, configured to control the output voltage of the DC energy storage valve according to a measured value of an output electrical signal of a DC side of the voltage source converter valve and an output voltage reference value of the DC energy storage valve; The second control module is used to control the output signal of the AC side of the voltage source converter valve according to the measured value of the grid-connected point electrical signal of the voltage source converter valve and the reference value of the grid-connected point electrical signal.

22. A control device for an energy storage system, comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 20 are implemented.

23. A computer-readable storage medium having a computer program stored thereon, wherein: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 20 are implemented.

24. A computer program product comprising a computer program, wherein: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 20 are implemented.

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