Power system energy storage control method and device

Abstract

The invention discloses an electric power system energy storage control method and device, and relates to the technical field of electric power. The method comprises the following steps: acquiring a basic control framework of network construction energy storage, and determining a virtual synchronous general control strategy of a network construction energy storage system; based on a virtual synchronous general control strategy, analyzing and calculating active output characteristics and reactive output characteristics of network construction energy storage under a current limiting condition by utilizing a vector diagram, active quantitative calculation and reactive quantitative calculation to obtain an analysis result; on the basis of an analysis result, an annular current limiting controller and a current limiting factor of the constructed energy storage in a power grid low-voltage scene, determining a limiting phase of each current and a corresponding output current characteristic when the constructed energy storage triggers current limitation, and generating a control strategy of the constructed energy storage; and when determining that the voltage of the power grid meets the target condition, simulating the operation of the power generation equipment based on the output current characteristics selected in the control strategy and controlling the power grid. The method is used for realizing the energy storage control function of the power system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power, in particular to a power system energy storage control method and device. BACKGROUND

[0002] With the acceleration of global energy transformation, electrochemical energy storage technology, as a key means to support large-scale access of renewable energy and flexible operation of power grid, is being applied more and more widely. In the control mode of grid-connected operation of energy storage system, traditional grid-following control and emerging grid-forming control are two main technical paths. Among them, grid-forming control makes the energy storage system present voltage source control characteristics to the outside, and provides inertia support for the grid by simulating the inertia and primary frequency modulation dynamic process of synchronous generator. However, in the low voltage scenario caused by power grid fault or large disturbance, the grid-forming energy storage system is easy to trigger current limit, resulting in that the active and reactive power cannot be accurately quantitatively controlled, which brings great challenges to its low voltage ride-through capability.

[0003] At present, in order to solve the problem of low voltage ride-through of power grid, the existing research proposes a method of adding a virtual impedance control link, so that the grid-forming energy storage does not trigger current limit, and then realizes low voltage ride-through by adjusting the voltage reference value. However, in actual application, although this method can avoid the current limit problem to some extent, the limiting effect of this method on output current in extreme transient time is not ideal, and the active and reactive output is greatly affected by the virtual impedance parameter, so it is difficult to realize quantitative control in the fault process. Therefore, how to realize a more effective and reliable low voltage ride-through control strategy to control the circuit system energy storage has become a problem to be solved in the field. SUMMARY

[0004] The embodiments of the present application provide a power system energy storage control method and device, and the main purpose is to realize the function of a more effective and reliable low voltage ride-through control strategy to control the circuit system energy storage.

[0005] To solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0006] In a first aspect, the present application provides a power system energy storage control method, which comprises:

[0007] obtaining the basic control architecture of the grid-forming energy storage, and determining the virtual synchronous general control strategy of the grid-forming energy storage system based on the basic control architecture, so as to simulate the operation of the power generation equipment of the power grid based on the virtual synchronous general control strategy;

[0008] based on the virtual synchronous general control strategy, using vector diagram and active quantitative calculation and reactive quantitative calculation, analyzing and calculating the active output characteristics and the reactive output characteristics of the grid-forming energy storage under current limit, to obtain the analysis result;

[0009] Based on the analysis result, the limiting phase of each current and the corresponding output current characteristic when the grid-connected energy storage triggers current limiting are determined by the ring-shaped current limiting controller in combination with the current limiting factors of the grid-connected energy storage in the low-voltage scenario of the power grid, and a low-voltage ride-through control strategy of the grid-connected energy storage is generated.

[0010] When it is determined that the grid voltage meets a target condition, the output current characteristic selected in the low-voltage ride-through control strategy of the grid-connected energy storage based on the limiting phase of the current is used to simulate the operation of the power generation equipment and control the power grid, wherein the target condition at least includes a voltage threshold.

[0011] In a second aspect, the present application further provides a power system energy storage control device, the device comprising:

[0012] A determination unit is configured to obtain a basic control architecture of the grid-connected energy storage, and determine a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, so as to simulate the operation of the power generation equipment of the power grid based on the virtual synchronous general control strategy.

[0013] An analysis unit is configured to analyze and calculate the active power output characteristic and the reactive power output characteristic of the grid-connected energy storage under current limiting based on the virtual synchronous general control strategy, by using vector diagrams and active power quantitative calculation and reactive power quantitative calculation, to obtain an analysis result.

[0014] A generation unit is configured to determine the limiting phase of each current and the corresponding output current characteristic when the grid-connected energy storage triggers current limiting based on the analysis result, by the ring-shaped current limiting controller in combination with the current limiting factors of the grid-connected energy storage in the low-voltage scenario of the power grid, and generate a low-voltage ride-through control strategy of the grid-connected energy storage.

[0015] An execution unit is configured to simulate the operation of the power generation equipment and control the power grid based on the output current characteristic selected in the low-voltage ride-through control strategy of the grid-connected energy storage based on the limiting phase of the current when it is determined that the grid voltage meets a target condition, wherein the target condition at least includes a voltage threshold.

[0016] In a third aspect, an embodiment of the present application provides a storage medium comprising a stored program, wherein the device where the storage medium is located executes the power system energy storage control method of any one of the first aspect when the program runs.

[0017] In a fourth aspect, embodiments of the present application provide an energy storage control device for a power system, the device comprising a storage medium; and one or more processors coupled to the storage medium, the processors configured to execute program instructions stored in the storage medium; the program instructions, when executed, performing the energy storage control method of any one of the first aspect.

[0018] By means of the technical solutions described above, the technical solutions provided by the present application have at least the following advantages:

[0019] The application provides a power system energy storage control method and device, which can obtain a basic control architecture of network-forming energy storage, determine a virtual synchronous general control strategy of a network-forming energy storage system based on the basic control architecture, simulate operation of power generation equipment of a power grid based on the virtual synchronous general control strategy, then analyze and calculate active output characteristics and reactive output characteristics of the network-forming energy storage under current limiting based on the virtual synchronous general control strategy, active quantitative calculation and reactive quantitative calculation, and vector diagrams, obtain analysis results, then determine a limiting phase of each current and corresponding output current characteristics when the network-forming energy storage triggers current limiting and generate a low-voltage ride-through control strategy of the network-forming energy storage based on the analysis results, the current limiting factor of the network-forming energy storage under a low-voltage scenario of the power grid, and a ring current limiting controller, and finally simulate operation of the power generation equipment and control the power grid based on the output current characteristics selected in the low-voltage ride-through control strategy of the network-forming energy storage according to the limiting phase of the current when it is determined that the voltage of the power grid meets a target condition, wherein the target condition at least includes a voltage threshold, thereby realizing the power system energy storage control function. Compared with the prior art, the application no longer needs to add a virtual impedance control link to the power grid, so the problem of unsatisfactory limiting effect of output current in extreme transient time caused by the virtual impedance does not exist, and in the application, the influence of active power and reactive power is considered and no virtual impedance is set, so the influence of the virtual impedance parameter on low-voltage ride-through does not exist. Therefore, compared with the prior art, the application realizes a low-voltage ride-through function of the power grid without the need for virtual impedance, avoids the problem of unsatisfactory limiting effect of output current in extreme transient time caused by setting a virtual impedance and controlling, and the problem of great influence of the virtual impedance parameter on active power and reactive power output, and difficulty in realizing quantitative control in a fault process, thereby ensuring that the application is more effective and reliable than the prior art. In addition, in the process of obtaining the basic control architecture and determining the virtual synchronous general control strategy, the power system energy storage control process of the application can ensure that the network-forming energy storage system can simulate the operation characteristics of the power generation equipment, such as inertia support and primary frequency modulation, can enhance the stability of the power grid, and in the process of analyzing the active and reactive output characteristics under current limiting, the application can use vector diagrams and quantitative calculation to determine the active and reactive output characteristics of the network-forming energy storage under different current limiting phases, thereby providing data support for subsequent control strategies.And, in determining the current limiting phase and output current characteristic and generating the control strategy, the current limiting phase and output current characteristic when triggering current limiting can be determined based on the analysis result through the ring current limiting controller, so as to generate the low voltage ride through control strategy, lay a foundation for subsequent application of the control strategy when the grid voltage meets the target condition, and in addition, in the present application, when the grid voltage drops more than the preset threshold and the current reaches the limit, the current limiting phase is adjusted, so that the grid energy storage system outputs reactive power to support voltage and does not output active power, which can help the grid to quickly recover stable operation.

[0020] The above description is only a summary of the technical solutions of the present application, in order to enable the technical means of the present application to be more clearly understood and implemented according to the content of the specification, and in order to enable the above and other purposes, features and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which a number of embodiments of the present application are shown by way of example, and wherein like reference numerals refer to like elements throughout. In the drawings:

[0022] Figure 1 A flow chart of a power system energy storage control method provided by an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram of a specific implementation scenario of a power system energy storage control method provided by an embodiment of the present application is shown;

[0024] Figure 3 A composition block diagram of a power system energy storage control device provided by an embodiment of the present application is shown;

[0025] Figure 4 A composition block diagram of another power system energy storage control device provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application can be more thoroughly understood and the scope of the present application can be accurately conveyed to those skilled in the art.

[0027] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present application should be understood as the usual meaning understood by those skilled in the art to which the present application belongs.

[0028] The embodiment of the application provides a power system energy storage control method, specifically as shown in the figure, the method comprises the steps of: Figure 1

[0029] 101, acquire the basic control architecture of the networked energy storage, and determine the virtual synchronous general control strategy of the networked energy storage system based on the basic control architecture.

[0030] In the process of acquiring the basic control architecture of the networked energy storage, first, the hardware components of the networked energy storage system need to be fully understood, including battery energy storage units, power converters, control units, etc. For example, the single-stage energy storage PCS topology is relatively simple, the technology is relatively mature, and the conversion efficiency is high, but a higher DC bus voltage is required, and the management of the energy storage battery is more difficult, which is difficult to apply to higher voltage level energy storage systems. Second, the preliminary control logic of the networked energy storage system needs to be determined, that is, how to coordinate these hardware components to achieve the expected control target. In this process, the system operation mode, control algorithm, signal processing and other aspects are involved, so in the process of acquiring the basic control framework, not only the composition of each hardware, but also the control and operation relationship between each hardware.

[0031] After acquiring the basic control architecture, the virtual synchronous general control strategy can be determined. The core of the virtual synchronous general control strategy is to simulate the operating characteristics of a synchronous generator. The synchronous generator has inertia support and primary frequency modulation characteristics, and can adjust its output power according to the change of the grid frequency to maintain the stability of the grid frequency. Then, by embedding the mathematical model of the synchronous generator into the control algorithm of the inverter, the networked energy storage system can simulate the electromagnetic equation and mechanical equation of the synchronous generator, thereby having inertia support and damping characteristics, and providing stable voltage and frequency support for the grid.

[0032] Specifically, the virtual synchronous general control strategy can be implemented in the following way:

[0033] First, inertia simulation: introduce virtual rotational inertia (J) and virtual damping (D) in the control algorithm, so that the networked energy storage system can simulate the inertia response and damping effect of the synchronous generator, and enhance the resistance of the system to frequency fluctuations.

[0034] Then, primary frequency modulation simulation: according to the deviation of the grid frequency, automatically adjust the output power of the networked energy storage system to maintain the stability of the grid frequency.

[0035] Finally, reactive power control: simulate the reactive power regulation characteristics of the synchronous generator to effectively support the grid voltage.

[0036] ​Of course, in the present example, the determination process of the quasi-synchronous general control strategy includes but is not limited to the above-mentioned manner, and the user can select based on the actual situation.

[0037] After determining the virtual synchronous general control strategy, the function of simulating the operation of the power generation equipment of the power grid is actually achieved. After determining the virtual synchronous general control strategy, the grid-connected energy storage system can adjust its operating state according to the strategy, so that its output characteristics are similar to those of a synchronous generator. For example, when the grid frequency rises, the grid-connected energy storage system will automatically reduce the active power output, and vice versa, thereby achieving primary frequency regulation. In addition, the grid-connected energy storage system can also adjust the reactive power output according to the change of the grid voltage, maintain the stability of the grid voltage, provide inertia support, reduce the fluctuation of the frequency and voltage, and enhance the stability of the grid.

[0038] In this way, by obtaining the basic control architecture of the grid-connected energy storage and determining the virtual synchronous general control strategy, it can be ensured that the grid-connected energy storage system can simulate the operation of the power generation equipment of the power grid, and the subsequent steps lay the foundation for providing effective support and stable operating environment for the power grid.

[0039] 102、Based on the virtual synchronous general control strategy, the active power output characteristics and the reactive power output characteristics of the grid-connected energy storage under current limiting are analyzed and calculated by using vector diagrams and active and reactive quantitative calculations, and an analysis result is obtained.

[0040] In the present embodiment, the virtual synchronous general control strategy can enable the grid-connected energy storage system to simulate the operating characteristics of a synchronous generator, such as inertia support and primary frequency regulation. The strategy introduces virtual rotational inertia and virtual damping into the inverter control algorithm, so that the system can adjust the output power according to the change of the grid frequency and maintain the stability of the grid frequency. Under this control strategy, the grid-connected energy storage system can dynamically adjust its output according to the change of the grid voltage and frequency to adapt to the demand of the power grid.

[0041] In the process of determining the vector diagram based on the virtual synchronous general control strategy, it is mainly divided into two parts, one of which is the process of drawing the vector diagram, and the other is the analysis process of the change characteristics based on the vector diagram. Among them, in the process of drawing the vector diagram, under the condition of current limiting, the situation when the voltage drops caused by power grid fault and large disturbance needs to be considered, and under this premise, the power grid voltage vector diagram and current vector diagram at this time are drawn. Among them, the vector diagram can directly show the amplitude, phase and other information of voltage and current, as well as the phase difference between them. In the analysis of the change characteristics of the vector diagram, the active and reactive output characteristics of the grid energy storage under different current limiting phases can be studied by observing the change characteristics of the vector diagram, such as the amplitude and phase change of the vector. Specifically, when the current phase is different, the angle between the output voltage and current will change, thereby affecting the active and reactive output.

[0042] After the vector diagram is determined, the active and reactive quantitative calculation can be carried out next, and the role of this step is mainly to compensate the power grid in the subsequent power system energy storage control process.

[0043] Specifically, in the process of active quantitative calculation, the active output of grid energy storage under different current limiting phases can be calculated according to the vector diagram and related formulas. The formula for calculating active power can be:

[0044] P = V x I x cos(θ)

[0045] Where P is the active power, V is the voltage, I is the current, and θ is the phase difference between voltage and current.

[0046] In the process of reactive quantitative calculation, it is also calculated according to the vector diagram and related formulas to calculate the reactive output of grid energy storage under different current limiting phases. Specifically, the formula for calculating reactive power is:

[0047] Q = V x I x sin(θ),

[0048] Where Q is the reactive power, V is the voltage, I is the current, and θ is the phase difference between voltage and current.

[0049] Get the analysis results:

[0050] Through the above analysis and calculation, the active and reactive output characteristics of grid energy storage under different current limiting phases can be obtained, that is, the analysis results. These results will provide data support for the subsequent control strategy formulation, helping to determine how to adjust the current phase and output in the low voltage ride through process to achieve the best control effect.

[0051] In this way, by using the vector diagram and active and reactive quantitative calculation based on the virtual synchronous general control strategy, the active output characteristics and the reactive output characteristics of the grid-connected energy storage under current limiting can be analyzed in detail, providing a scientific basis for the development of low-voltage ride-through control strategies.

[0052] 103、Based on the analysis results, the limiting phase of each current and the corresponding output current characteristics of the grid-connected energy storage when triggering current limiting are determined by the ring current limiting controller in combination with the current limiting factors of the grid-connected energy storage under the low-voltage scenario of the power grid, and a low-voltage ride-through control strategy for the grid-connected energy storage is generated.

[0053] Under current limiting, the active output characteristics and the reactive output characteristics of the grid-connected energy storage under different current limiting phases have been obtained through vector diagram and active and reactive quantitative calculation (i.e. analysis results). Next, the required input current characteristics under different current limiting phases can be determined based on the ring current limiting controller according to the current limiting factors of the grid-connected energy storage under the low-voltage scenario of the power grid. The ring current limiting controller is a device that can limit the current amplitude to prevent damage to equipment and the power grid caused by excessive current. In the grid-connected energy storage system, it can dynamically adjust the phase and amplitude of the current according to the depth of voltage sag and current limiting factors. In the process of determining the limiting phase of the current and the output current characteristics, the limiting phase of each current when triggering current limiting is first determined based on the analysis results and the current limiting factors under the low-voltage scenario of the power grid. For example, when the voltage of the power grid drops, the phase of the current is adjusted to make the grid-connected energy storage system output more reactive power to support the voltage of the power grid, while limiting the output of active power to avoid excessive current.

[0054] Next, in the process of determining the output current characteristics, the corresponding output current characteristics can be obtained according to the determined current limiting phase and the analysis results. This includes the specific values and trends of the active output and the reactive output of the grid-connected energy storage system under different phases.

[0055] After the current limiting phase and the output current characteristics are determined, the current limiting phase and the output current characteristics can be integrated into the control strategy to form a complete low-voltage ride-through control strategy. This strategy clearly defines how to adjust the current phase and output to achieve the best control effect when the voltage of the power grid is low. For example, when the voltage of the power grid drops beyond the preset threshold and the current reaches the limit, the low-voltage ride-through control strategy is triggered, and the output of the inverter is adjusted according to the pre-determined limiting phase and output current characteristics, so that the grid-connected energy storage system outputs reactive power to support the voltage of the power grid, without outputting active power, helping the power grid to quickly recover stable operation.

[0056] 104、When it is determined that the grid voltage meets the target condition, the output current characteristics selected in the grid-connected energy storage low voltage ride through control strategy simulate the operation of the power generation equipment and control the grid based on the current limit phase.

[0057] The target condition at least includes a voltage threshold.

[0058] In this step, it is first necessary to monitor the grid voltage in real time. In the process of monitoring the grid voltage in real time, the amplitude and phase information of the voltage can be obtained. This can be achieved by installing a voltage sensor in the grid. The sensor converts the voltage signal into an electrical signal and transmits it to the monitoring module of the control system. Then compare the monitored grid voltage with the preset target condition. Specifically, in the process of judging whether it meets the target condition, it can also be determined whether the start condition of the low voltage ride through control strategy is met according to the monitored grid voltage data. This involves real-time calculation and comparison of the voltage amplitude, for example, by comparing the difference between the current voltage and the rated voltage to determine the depth of voltage drop. Further, in this embodiment, whether to execute the grid-connected energy storage low voltage ride through control strategy can be determined based on the target condition, which at least includes a voltage threshold. That is, when the voltage of the grid is as low as the threshold, it means that the grid voltage meets the target condition and the grid-connected energy storage low voltage ride through control strategy needs to be executed.

[0059] For example, when the depth of grid voltage drop exceeds the preset 0.2p.u. (voltage threshold), it is considered that the grid voltage meets the target condition, triggering the low voltage ride through control strategy.

[0060] If the grid voltage meets the target condition, that is, the depth of voltage drop exceeds the preset threshold, and the output current of the grid-connected energy storage inverter reaches the current limit, the control system will enter the low voltage ride through control mode. In the execution of the selected output current characteristics:

[0061] In the low voltage ride through control mode, the embodiment selects the corresponding output current characteristics from the pre-generated low voltage ride through control strategy according to the current limit phase. This includes determining the reference values of the reactive power and active power that the grid-connected energy storage system should output at this phase.

[0062] For example, according to the output current characteristic description equation of the ring current limiter

[0063] Id=Imaxcos(φ)

[0064] Iq=Imaxsin(φ)

[0065] wherein Id is the d-axis output current of the inverter in current limiting state, Iq is the q-axis output current of the inverter in current limiting state, φ is the current phase of the inverter in current limiting state, and Imax is the amplitude of the current limit. By adjusting the current phase The output of reactive power can be controlled to support the grid voltage.

[0066] Next, the control parameters of the inverter can be adjusted according to the selected output current characteristics, so that the grid-connected energy storage system simulates the operation of the power generation equipment. Specifically, by controlling the output current of the inverter, the grid-connected energy storage system does not output active power under low voltage conditions, but outputs full reactive power to maximize the reactive voltage support capability.

[0067] For example, by setting the reference value of the current inner loop, the inverter outputs more reactive current, thereby increasing the reactive power of the grid and improving the grid voltage. At the same time, the output of active current is limited to avoid excessive current and protect the safety of equipment and the grid.

[0068] The control system continuously monitors the grid voltage and current to adjust the control parameters in real time, ensuring that the grid-connected energy storage system always operates according to the predetermined control strategy during low voltage ride through, effectively supporting the grid voltage and helping the grid to quickly recover stable operation.

[0069] In this way, based on the method of the present step, the output current characteristics selected in the low voltage ride through control strategy of the grid-connected energy storage system based on the current limit phase can simulate the operation of the power generation equipment and control the grid when the grid voltage meets the target conditions, achieving effective and reliable low voltage ride through function.

[0070] Compared with the prior art, in the scheme of the application, the virtual impedance control link for the power grid is no longer needed, so the problem of the unsatisfactory limiting effect of the output current in the extreme transient time caused by the virtual impedance does not exist, and in the application, the active and reactive power influences are considered, and the virtual impedance is not set, so the influence of the virtual impedance parameter on the low voltage ride through also does not exist. Therefore, compared with the prior art, in the application, the low voltage ride through function of the power grid based on the virtual impedance is not needed, compared with the unsatisfactory limiting effect of the output current in the extreme transient time caused by the setting of the virtual impedance and the control, and the active and reactive power output is greatly influenced by the virtual impedance parameter, the problem of difficult quantitative control in the fault process is also avoided, so that the application is more effective and reliable compared with the prior art. In addition, in the process of obtaining the basic control architecture and determining the virtual synchronous general control strategy, the power system energy storage control process of the application can ensure that the grid-connected energy storage system can simulate the operating characteristics of the power generation equipment, such as inertia support and primary frequency modulation, which can enhance the stability of the power grid, and in the process of analyzing the active and reactive power output characteristics under current limiting conditions, the active and reactive power output characteristics of the grid-connected energy storage under different current limiting phases can be determined by using vector diagrams and quantitative calculation, which provides data support for subsequent control strategies. And when the limiting phase and the output current characteristics are determined and the control strategy is generated, the limiting phase and the output current characteristics when the current limiting is triggered can be determined based on the analysis results through the ring current limiting controller, so as to generate the low voltage ride through control strategy, which lays a foundation for subsequent application of the control strategy when the grid voltage meets the target condition, in addition, in the application, when the grid voltage drops more than the preset threshold and the current reaches the limit, the limiting phase of the current is adjusted, so that the grid-connected energy storage system outputs reactive power to support the voltage and does not output active power, which can help the power grid to quickly recover stable operation.

[0071] Further, as a refinement and extension of the above-mentioned embodiments, in some embodiments,

[0072] An equivalent simplified grid-connected topology of the grid-connected energy storage system is obtained, and a control architecture of a controllable grid-connected inverter is determined, based on the equivalent simplified grid-connected topology and the control architecture of the controllable grid-connected inverter, a corresponding virtual synchronous control general control architecture and a general control architecture control strategy are determined;

[0073] The virtual synchronous control general control architecture and the general control architecture control strategy are used to simulate the operation of the power generation equipment, the corresponding active synchronous ring control algorithm is set, the inverter output active power is adjusted according to the grid frequency deviation, and the decoupling control algorithm is used to independently adjust the voltage outer ring and the current inner ring respectively, so as to determine the virtual synchronous active synchronous ring general control strategy and the double-loop decoupling general control strategy of the grid-connected inverter.

[0074] Implementation process: First, the equivalent simplified grid-connected topology of the grid-forming energy storage system is obtained, which involves simplifying the complex system, retaining key characteristics and parameters, to facilitate analysis and control. At the same time, the control architecture of the controllable grid-connected inverter is determined, and its hardware structure and basic control logic are clarified. Based on this, the virtual synchronous control general control architecture and strategy are determined, laying the foundation for subsequent control strategies. Then, the virtual synchronous control general control architecture and strategy are used to simulate the operation of the power generation equipment, set the active synchronous ring control algorithm, and adjust the inverter output active power in real time according to the grid frequency deviation to adapt to the grid frequency change. The decoupling control algorithm is used to independently adjust the voltage outer ring and current inner ring, eliminating the mutual influence between them, improving the control accuracy and response speed, so as to determine the virtual synchronous active synchronous ring general control strategy and double-loop decoupling general control strategy of the grid-connected inverter.

[0075] Effects and benefits: This embodiment details how to determine the virtual synchronous active synchronous ring general control strategy and double-loop decoupling general control strategy, and through simulating the operation of the power generation equipment and using advanced control algorithms, the grid-forming energy storage system can better adapt to the grid frequency change and improve the support capability of the grid. The application of decoupling control algorithm makes the control of voltage and current more accurate and independent, improves the dynamic performance and stability of the system, and provides a solid foundation for the subsequent low voltage ride through control strategy.

[0076] Further, as a refinement and extension of the above-mentioned embodiments, in some embodiments, the aforementioned embodiment "step 101, obtaining the basic control architecture of the grid-forming energy storage, and determining the virtual synchronous general control strategy of the grid-forming energy storage system based on the basic control architecture", when executed, can include:

[0077] Obtaining the equivalent simplified grid-connected topology of the grid-forming energy storage system, and determining the control architecture of the controllable grid-connected inverter, based on the equivalent simplified grid-connected topology and the control architecture of the controllable grid-connected inverter, determining the corresponding virtual synchronous control general control architecture and general control architecture control strategy;

[0078] Simulating the operation of the power generation equipment through the virtual synchronous control general control architecture and general control architecture control strategy, setting the corresponding active synchronous ring control algorithm, and adjusting the inverter output active power according to the grid frequency deviation, and then using the decoupling control algorithm to independently adjust the voltage outer ring and current inner ring, to determine the virtual synchronous active synchronous ring general control strategy and double-loop decoupling general control strategy of the grid-connected inverter.

[0079] In this embodiment, in the process of obtaining the equivalent simplified grid-connected topology of the grid-connected energy storage system, the specific process can be: the equivalent simplified grid-connected topology of the grid-connected energy storage system is a simplification and equivalence of its actual structure, in order to facilitate analysis and control. Common topology structures include single-stage energy storage PCS topology, double-stage energy storage PCS topology, cascaded energy storage PCS topology, and MMC topology, etc. Each topology structure has its characteristics and application scenarios. For example, the single-stage energy storage PCS topology structure is relatively simple and has high conversion efficiency, but requires a higher DC bus voltage, which is difficult to apply to higher voltage grade energy storage systems; while the cascaded energy storage PCS topology presents a modular structure, which can improve the system voltage level and facilitate power control of the DC energy storage unit and fault-tolerant control of the system.

[0080] Next, the control architecture of the controllable grid-connected inverter can be determined, wherein the control architecture of the controllable grid-connected inverter is the key to achieving precise control of the inverter. It involves how to coordinate various components of the inverter, such as PWM converters, filters, transformers, etc., to achieve the expected control objectives, including power control, voltage control, frequency control, etc. The design of the control architecture needs to consider factors such as system stability, dynamic performance, and control accuracy.

[0081] In the process of determining the virtual synchronous control general control architecture and the general control architecture control strategy, the virtual synchronous control general control architecture is constructed based on the virtual synchronous generator (VSG) control strategy. VSG control simulates the electromagnetic equation and mechanical equation of a synchronous generator, enabling the inverter to have inertia support and damping characteristics, and can adjust the output power according to the change of the grid frequency to maintain the stability of the grid frequency. The general control architecture control strategy includes the setting and adjustment of VSG control parameters, such as virtual rotational inertia (J) and damping coefficient (D), to adapt to different grid operating conditions.

[0082] In this embodiment, in the process of setting the active synchronous loop control algorithm based on the simulation of the operation of the power generation equipment, based on the virtual synchronous control general control architecture and the general control architecture control strategy, the grid-connected energy storage system can simulate the operating characteristics of the power generation equipment. Setting the active synchronous loop control algorithm enables the system to automatically adjust the output active power according to the grid frequency deviation, achieving primary frequency regulation function. For example, when the grid frequency rises, the system will automatically reduce the active power output, and vice versa, thereby maintaining the stability of the grid frequency.

[0083] Next, when the decoupling control algorithm is used to independently adjust the voltage outer loop and the current inner loop, the decoupling control algorithm is used to eliminate the mutual influence between the voltage outer loop and the current inner loop, and improve the accuracy and response speed of the control system. Through decoupling control, the voltage outer loop and the current inner loop can be independently adjusted, so that each control loop can better achieve its control target. For example, the voltage outer loop is responsible for controlling the amplitude of the output voltage, and the current inner loop is responsible for controlling the size and phase of the output current, thereby realizing accurate control of the output of the grid-connected energy storage system.

[0084] In this way, through the above steps, the virtual synchronous active synchronous loop general control strategy and the double-loop decoupling general control strategy suitable for the grid-connected energy storage system can be constructed, so that the system has good dynamic performance and stable output capacity in grid-connected operation, and the stability and reliability of the power grid are enhanced.

[0085] Further, as a refinement and extension of the above-mentioned embodiments, in some embodiments, in the aforementioned embodiments, "in step 102, based on the virtual synchronous general control strategy, the current output characteristics and the reactive output characteristics of the grid-connected energy storage under current limiting are analyzed and calculated by using vector diagrams and active and reactive quantitative calculations, and analysis results are obtained", when executed, it can be specifically:

[0086] First, according to the current output characteristics of the grid-connected energy storage grid-connected converter under current limiting, the voltage vector diagram and the current vector diagram of the power grid when the voltage drops after the power grid fault and disturbance are determined;

[0087] Then, by the change characteristics of the voltage vector diagram and the current vector diagram, the quantitative calculation method and the output characteristic description of the active output characteristics and the reactive output characteristics of the grid-connected energy storage under different current limiting phases are determined.

[0088] In this embodiment, under current limiting, the current output characteristics of the grid-connected energy storage grid-connected converter are analyzed, which needs to consider the situation when the voltage drops due to power grid fault and large disturbance, and the voltage vector diagram and the current vector diagram at that time are drawn based on this. In this way, by observing the change characteristics of the vector diagram, such as the amplitude and phase change of the vector, the active and reactive output characteristics of the grid-connected energy storage under different current limiting phases can be analyzed. Based on this, a quantitative calculation method is established, which can accurately calculate the active and reactive output of the grid-connected energy storage under different current limiting phases, and describe the output characteristics in detail, providing data support for subsequent control strategy formulation.

[0089] Based on the method of the present step, the embodiment determines the influence of the current-limiting phase on the active and reactive power output characteristics of the grid-connected energy storage through detailed vector diagram analysis and quantitative calculation, thereby providing a scientific basis for phase adjustment in the low-voltage ride-through control strategy. At the same time, it is also helpful to accurately adjust the current phase, optimize the reactive power output, improve the voltage support capability of the grid, and enhance the stability of the system under actual fault conditions.

[0090] Further, as a refinement and extension of the above-mentioned embodiments, in some embodiments, the output current characteristics specifically include an output current characteristic description equation.

[0091] Based on this, the aforementioned embodiment "step 103, based on the analysis results, determines the limiting phase of each current and the corresponding output current characteristics of the grid-connected energy storage when triggering current limiting through the ring-shaped current limiting controller in combination with the current limiting factors of the grid-connected energy storage under low-voltage grid scenarios, and generates a low-voltage ride-through control strategy for the grid-connected energy storage" can include the following when executed:

[0092] First, based on the analysis results, the basic working principle of the ring-shaped current limiting controller is determined, and the output current characteristic description equation containing the limiting phase of the current under the action of the ring-shaped current limiting controller is determined.

[0093] Then, based on the output current characteristic description equation, the output current corresponding to each current limiting phase is determined, and the low-voltage ride-through control strategy for the grid-connected energy storage is generated.

[0094] In the present embodiment, the process of determining the basic working principle of the ring-shaped current limiting controller is as follows, wherein the ring-shaped current limiting controller is a device capable of limiting the amplitude of the current to prevent damage to equipment and the grid caused by excessive current. Its basic working principle is to limit the amplitude of the current so that the current is limited within a safe range when it exceeds the set threshold. Specifically, the detailed analysis of the working principle is as follows: when the grid experiences a fault or a large disturbance leading to voltage drop, the output current of the grid-connected energy storage system may increase sharply. In this process, the ring-shaped current limiting controller will monitor the amplitude of the current in real time, and once the current exceeds the preset current limiting value, the controller will quickly adjust the control parameters of the inverter to limit the further increase of the current. This adjustment is usually achieved by changing the output phase of the inverter to change the size and direction of the output current.

[0095] Next, the output current characteristic description equation containing the current limiting phase can be determined. Specifically, under the action of the ring-shaped current limiting controller, the characteristics of the output current can be described by a mathematical equation. Based on the description of the aforementioned embodiment, the output current characteristic description equation can be expressed as:

[0096] Id = Imaxcos(φ)

[0097] Iq = Imaxsin(φ)

[0098] where Id is the d-axis output current of the inverter in current-limited state, Iq is the q-axis output current of the inverter in current-limited state, φ is the current phase of the inverter in current-limited state, and Imax is the amplitude of current limit.

[0099] These two equations describe the relationship between the d-axis and q-axis components of the inverter output current and the current phase in current-limited state. By adjusting the current phase φ, the size and direction of the output current can be controlled, thereby achieving the regulation of reactive power and active power.

[0100] After determining the equations, the output current corresponding to each current limit phase can be determined. Specifically, based on the above output current characteristic description equation, the output current of the inverter under different current limit phases can be calculated. For example, when the current phase φ is 0 degrees, the d-axis output current Id reaches the maximum value Imax, and the q-axis output current Iq is 0; when the current phase φ is 90 degrees, the q-axis output current Iq reaches the maximum value Imax, and the d-axis output current Id is 0.

[0101] Here is a specific calculation example:

[0102] Assuming the current limit amplitude Imax is 1.2 p.u., when the current phase φ is 30 degrees, the calculation results are:

[0103]

[0104] Based on this, it is shown that under the 30-degree phase, the d-axis output current is about 1.039 p.u., and the q-axis output current is 0.6 p.u.

[0105] After determining the output current corresponding to different current limit phases, the relationship between them can be added to the control strategy. Specifically, during the formulation of the control strategy, the above calculation results can be integrated into the control strategy to form a complete low voltage ride through control strategy. This strategy clearly shows how to adjust the current phase and output to achieve the best control effect when the grid voltage fails.

[0106] Specifically, when the grid voltage drops beyond the preset threshold and the current reaches the limit, the low voltage ride through control strategy is triggered. According to the pre-determined current limit phase and output current characteristics, the output of the inverter is adjusted to make the grid energy storage system output reactive power to support the grid voltage, without outputting active power. For example, by setting the current phase φ to 90 degrees, the inverter mainly outputs reactive current, thereby increasing the reactive power of the grid and improving the grid voltage.

[0107] Through the above steps, the behavior of the grid-connected energy storage system during low-voltage fault can be accurately controlled, the fault current can be effectively limited, the equipment can be protected, and the reactive voltage support capability can be maximized to achieve effective and reliable low-voltage ride-through function.

[0108] Further, as a refinement and extension of the above embodiments, in some embodiments, the "step 104, when it is determined that the grid voltage meets the target condition, the output current characteristic selected in the grid-connected energy storage low-voltage ride-through control strategy based on the current limit phase simulates the operation of the power generation equipment and controls the grid" in the foregoing embodiments, when executed, can be:

[0109] Step S1, when it is determined that the voltage drop depth exceeds the preset threshold, and the output current of the grid-connected energy storage grid-connected inverter reaches the current limit, it is determined that the grid voltage meets the target condition;

[0110] Step S2, when the grid voltage meets the target condition, the current limit phase and the corresponding output current are adjusted in real time based on the grid-connected energy storage low-voltage ride-through control strategy, so that the grid-connected energy storage system does not output active power when the grid voltage meets the target condition, but outputs full reactive power, so as to enhance the reactive voltage support capability of the grid-connected energy storage system to perform low-voltage ride-through.

[0111] In this embodiment, the grid voltage needs to be monitored in real time. When it is detected that the voltage drop depth exceeds the preset threshold, and the output current of the grid-connected energy storage grid-connected inverter reaches the current limit, it is determined that the grid voltage meets the target condition. At this time, according to the grid-connected energy storage low-voltage ride-through control strategy, immediate action is taken to adjust the current limit phase and its corresponding output current in real time. Specifically, by dynamically changing the phase angle of the current, it is ensured that the grid-connected energy storage system stops outputting active power under this condition, and uses all its capacity to output reactive power. This process can enhance the reactive voltage support capability of the grid-connected energy storage system, provide strong voltage support for the grid during low-voltage fault, and help the grid quickly recover to stable operation.

[0112] In this way, the method based on this embodiment clearly defines the starting condition and specific control measures of the low-voltage ride-through control strategy, ensuring that when the grid voltage drops severely and the current reaches the limit, the grid-connected energy storage system can quickly and accurately adjust the operating state, not output active power but output reactive power with full capacity. Such precise control measures can effectively avoid fault expansion, enhance the anti-disturbance capability of the grid, improve the success rate of low-voltage ride-through, and ensure the safe and stable operation of the power system.

[0113] Further, as a refinement and extension of the above embodiments, in some embodiments, the aforementioned "step S2, adjusting the phase of the current limit in real time based on the network-forming energy storage low-voltage ride-through control strategy and the corresponding output current" in the aforementioned embodiments includes:

[0114] Based on the network-forming energy storage low-voltage ride-through control strategy, the value of the phase of the current limit is dynamically adjusted to keep the angle between the output voltage vector and the current vector of the network-forming energy storage within a preset range, so that the network-forming energy storage system provides reactive voltage support for the power grid.

[0115] In this embodiment, first of all, it is necessary to ensure real-time monitoring of the state of the power grid. During the operation of the power grid, the changes of the voltage and current of the power grid are monitored in real time, especially the voltage drop and current limit of the power grid. This can be achieved by sensors installed in the power grid, which convert the voltage and current signals into electrical signals and transmit them to the monitoring module of the control system. When the voltage drop of the power grid is monitored to exceed the preset threshold and the output current of the network-forming energy storage grid-connected inverter reaches the current limit, the low-voltage ride-through control strategy is triggered. At this time, the control system enters the low-voltage ride-through control mode and starts to dynamically adjust the phase of the current limit. Specifically, during the adjustment of the phase of the current, the phase of the current limit can be dynamically adjusted according to the low-voltage ride-through control strategy. This is usually achieved by changing the control parameters of the inverter, such as adjusting the output phase angle of the inverter. The goal of adjustment is to keep the angle between the output voltage vector and the current vector of the network-forming energy storage within a preset range to ensure the effective output of reactive power.

[0116] Further, in the process of keeping the angle between the output voltage vector and the current vector within a preset range, it is generally necessary to first determine the preset range, wherein the preset range is determined according to the operation requirements of the power grid and the performance of the equipment, and is usually a small range, such as 0 to 90 degrees. This range ensures the effective output of reactive power while avoiding excessive output of active power. Then the angle is calculated in real time. In the low-voltage ride-through control mode, the control system calculates the angle between the output voltage vector and the current vector of the network-forming energy storage in real time. This can be achieved by vector diagram and related formulas, such as:

[0117]

[0118] Wherein θ is the angle between the output voltage vector and the current vector, Id is the d-axis output current, and Iq is the q-axis output current.

[0119] Next, the control parameters are adjusted. If the calculated angle exceeds the preset range, the control system will adjust the control parameters of the inverter, such as adjusting the phase angle of the current, to make the angle return to the preset range. This can be achieved by increasing or decreasing the phase angle of the current, and the specific adjustment direction depends on the current value and target value of the angle.

[0120] In the process of providing reactive power, for reactive power, it belongs to limit the phase of the dynamic adjustment of current, make the network energy storage system mainly output reactive power, rather than active power. The output of reactive power can effectively support the grid voltage, help the grid quickly recover stable operation.

[0121] For example, when the current phase angle is adjusted to 90 degrees, the network energy storage system mainly outputs reactive power, at this time the d-axis output current is 0, and the q-axis output current reaches the maximum. This can be represented by the following formula:

[0122] I d =I max cos(90°)=0

[0123] I q =I max sin(90°)=I max

[0124] Where, Imax is the amplitude of the current limit.

[0125] In this way, by outputting reactive power, the network energy storage system can provide maximum reactive power support during low voltage fault, help to improve the grid voltage, reduce the impact of voltage drop on the grid, and enhance the stability and reliability of the grid.

[0126] Based on the above description, in the embodiment, through the above steps, the behavior of the network energy storage system during low voltage fault can be accurately controlled, the fault current can be effectively limited, the equipment can be protected, and the maximum reactive voltage support capability can be achieved. Effective and reliable low voltage ride through function.

[0127] Further, as a refinement and extension of the above embodiment, in some embodiments, the virtual synchronous general control strategy specifically includes a virtual synchronous active synchronous ring control strategy of a grid-connected inverter and a double-loop decoupling control strategy of a voltage outer loop and a current inner loop; wherein the virtual synchronous active synchronous ring control strategy of the grid-connected inverter is used to simulate the swing characteristics of a synchronous generator and determine the dq axis phase in the current coordinate system accordingly; the double-loop decoupling control strategy of the voltage outer loop and the current inner loop is specifically used to generate the PWM control signal of the grid-connected inverter of the network energy storage system through the cascade control of the voltage outer loop and the current inner loop.

[0128] In this embodiment, the virtual synchronous general control strategy is composed of two parts: the virtual synchronous active synchronous loop control strategy of the grid-connected inverter, and the double-loop decoupling control strategy of the voltage outer loop and the current inner loop. The former is used to simulate the swing characteristics of the synchronous generator, determine the dq axis phase in the current coordinate system through a specific algorithm, make the inverter output power able to self-adjust according to the grid frequency change, provide inertia support and primary frequency modulation function. The latter generates accurate PWM control signals through the cascade control of the voltage outer loop and the current inner loop, adjusts the output voltage and current of the inverter, ensures that it operates according to the predetermined control target, and realizes effective support and stable control of the grid.

[0129] Based on the method of this embodiment, the specific composition and function of the virtual synchronous general control strategy are determined, and the grid-connected energy storage system has good dynamic performance and stable output capacity by simulating the characteristics of the synchronous generator and adopting the double-loop decoupling control. This control strategy can effectively improve the adaptability and support of the grid-connected energy storage system to the grid, enhance the stability and reliability of the grid, and provide a solid technical guarantee for the operation of the grid under complex conditions such as low voltage ride through.

[0130] Further, as a further extension and refinement of the above-mentioned embodiments, in this embodiment, the virtual synchronous general control strategy can also be combined with Figure 2 The execution process of the power system energy storage control is described exemplarily, which can be specifically:

[0131] Among them, Figure 2 A system architecture for executing a power system energy storage control method is shown, which is divided into three parts: grid side, grid-connected energy storage side and control module. Specifically as follows:

[0132] Grid side: the alternating current grid on the left side of the figure is represented by a circle and a sine wave, with a voltage of Vg∠θg, connected to the grid-connected energy storage system through reactance Xvsg.

[0133] Grid-connected energy storage side: contains a voltage source converter (VSC) that converts the DC side battery energy storage system (BESS) electrical energy into alternating current electrical energy and feeds it into the grid. The AC side voltage of the converter is Vc∠θvsg, connected to the grid through reactance Xf.

[0134] Control module: includes active synchronous control loop and reactive synchronous control loop, respectively adjusts active power P and reactive power Q, and realizes control of the output of the converter.

[0135] The specific control process is:

[0136] Active control: the grid power signals P and Q are input to the active synchronous control loop, and the active power reference value Pref is obtained after processing, to adjust the output active power of the converter.

[0137] Reactive control: the reactive power reference value Qref is input to the reactive loop, and the converter output reactive power is adjusted to support the grid voltage.

[0138] Voltage and current control: the voltage outer loop outputs current reference value idref, iqref according to reference voltage vdref, vqref, and compares with actual current id0, iq0 after limiting the amplitude value by current limiting module, and the current inner loop adjusts and outputs PWM signal to control the converter.

[0139] In this process, the synchronous generator characteristics are simulated by the active synchronous control loop, so that the energy storage system has inertia support and primary frequency modulation capability. At the same time, the current limiting module limits the output current during low voltage ride through, protects the equipment and meets the grid requirements. In addition, in the low voltage ride through control strategy, by adjusting the current phase in real time, the converter outputs reactive power to support voltage during fault, and realizes low voltage ride through. The Figure 2 The architecture and process of the low voltage ride through control strategy of the grid-connected energy storage are intuitively presented, the specific process of virtual synchronous control, current limiting and dynamic phase adjustment is embodied, and the effect of low voltage ride through of the grid during the energy storage control of the power system is ensured.

[0140] In order to achieve the above purpose, according to another aspect of the present application, the embodiment of the present application also provides a power system energy storage control device, which comprises a storage medium and one or more processors, the storage medium is coupled with the processor, the processor is configured to execute program instructions stored in the storage medium, and the program instructions run to execute the power system energy storage control method.

[0141] Further, as the implementation of the above-mentioned Figure 1 And the implementation of the above-mentioned method, another embodiment of the present application also provides a power system energy storage control device. The power system energy storage control device embodiment corresponds to the foregoing method embodiment, for the convenience of reading, the details of the foregoing method embodiment will not be described one by one, but it should be clear that the system in the embodiment can correspondingly realize all the contents in the foregoing method embodiment. Specifically, as Figure 3 The power system energy storage control device comprises:

[0142] The determination unit 31 can be used to obtain the basic control architecture of the grid-connected energy storage, and determine the virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, so as to simulate the operation of the power generation equipment of the grid based on the virtual synchronous general control strategy.

[0143] The analysis unit 32 can be configured to analyze and calculate the active output characteristics and the reactive output characteristics of the grid-connected energy storage under current limiting conditions based on the virtual synchronous general control strategy obtained by the determination unit 31, by using vector diagrams and active quantitative calculation and reactive quantitative calculation, to obtain analysis results.

[0144] The generation unit 33 can be configured to determine the limiting phase of each current and the corresponding output current characteristics of the grid-connected energy storage when the current limiting is triggered, and generate a low-voltage ride-through control strategy of the grid-connected energy storage, based on the analysis results obtained by the analysis unit 32, by using a ring current limiting controller and combining the current limiting factors of the grid-connected energy storage in a low-voltage scenario of the power grid.

[0145] The execution unit 34 can be configured to simulate the operation of the power generation equipment and control the power grid based on the output current characteristics selected in the low-voltage ride-through control strategy of the grid-connected energy storage obtained by the generation unit 33, based on the limiting phase of the current when the voltage of the power grid meets the target condition, wherein the target condition at least includes a voltage threshold.

[0146] Further, as shown in Figure 4 The determination unit 31 can be configured to obtain an equivalent simplified grid-connected topology of the grid-connected energy storage system, determine a control architecture of the controllable grid-connected inverter, determine a corresponding virtual synchronous control general control architecture and a general control architecture control strategy based on the equivalent simplified grid-connected topology and the control architecture of the controllable grid-connected inverter, simulate the operation of the power generation equipment by using the virtual synchronous control general control architecture and the general control architecture control strategy, set a corresponding active synchronous ring control algorithm, adjust the output active power of the inverter according to the frequency deviation of the power grid, and then use a decoupling control algorithm to independently adjust the voltage outer ring and the current inner ring, respectively, to determine the virtual synchronous active synchronous ring general control strategy and the double-loop decoupling general control strategy of the grid-connected inverter.

[0147] Further, as shown in Figure 4 The analysis unit 32 can be configured to determine the voltage vector diagram and the current vector diagram of the power grid when the voltage drops after the power grid fault and disturbance based on the grid-connected energy storage grid-connected converter current output characteristics under current limiting conditions, and determine the quantitative calculation method and the output characteristic description of the active output characteristics and the reactive output characteristics of the grid-connected energy storage under the limiting phase of different currents by using the change characteristics of the voltage vector diagram and the current vector diagram.

[0148] Further, as shown in Figure 4 The output current characteristics specifically include an output current characteristic description equation.

[0149] The generation unit 33 comprises:

[0150] The first determination module 331 can be configured to determine the basic working principle of the ring-shaped current limiting controller based on the analysis result, and determine an output current characteristic description equation of the current limiting phase under the action of the ring-shaped current limiting controller.

[0151] The second determination module 332 can be configured to determine the output current corresponding to each current limiting phase based on the output current characteristic description equation obtained by the first determination module 331, and generate the grid-connected energy storage low-voltage ride-through control strategy.

[0152] Further, as shown in Figure 4 The execution unit 34 includes:

[0153] The first determination module 341 can be configured to determine that the grid voltage meets the target condition when it is determined that the voltage drop depth exceeds the preset threshold and the output current of the grid-connected energy storage inverter reaches the current limit.

[0154] The control module 342 can be configured to adjust the current limiting phase and the corresponding output current in real time based on the grid-connected energy storage low-voltage ride-through control strategy when the first determination module 341 determines that the grid voltage meets the target condition, so that the grid-connected energy storage system does not output active power and outputs full reactive power when the grid voltage meets the target condition, so as to improve the reactive voltage support capability of the grid-connected energy storage for low-voltage ride-through.

[0155] Further, as shown in Figure 4 The control module 342 can be configured to dynamically adjust the value of the current limiting phase based on the grid-connected energy storage low-voltage ride-through control strategy, so that the angle between the output voltage vector of the grid-connected energy storage and the current vector is kept within a preset range, so that the grid-connected energy storage system provides reactive voltage support for the grid.

[0156] Further, as shown in Figure 4 The virtual synchronous universal control strategy specifically includes a virtual synchronous active synchronous ring control strategy of the grid-connected inverter and a double-loop decoupling control strategy of a voltage outer loop and a current inner loop.

[0157] The virtual synchronous active synchronous ring control strategy of the grid-connected inverter can be configured to simulate the swing characteristics of a synchronous generator and determine the dq axis phase in the current coordinate system accordingly; the double-loop decoupling control strategy of the voltage outer loop and the current inner loop can be configured to generate the PWM control signal of the grid-connected energy storage inverter through the cascade control of the voltage outer loop and the current inner loop.

[0158] The embodiment of the present application provides a kind of power system energy storage control method and device, in the embodiment of the present application, the basic control architecture of network energy storage can be obtained, and the virtual synchronous general control strategy of network energy storage system is determined based on the basic control architecture, so as to simulate the operation of power generation equipment of power grid based on the virtual synchronous general control strategy;Then, based on the virtual synchronous general control strategy, using vector diagram and active quantitative calculation and reactive quantitative calculation, the active output characteristic and the reactive output characteristic of network energy storage under current limiting condition are analyzed and calculated, to obtain analysis result;Afterwards, based on the analysis result, through ring current limiting controller, in combination with the current limiting factor of network energy storage under low voltage scenario of power grid, the limiting phase of each current when network energy storage triggers current limiting and the corresponding output current characteristic are determined, and network energy storage low voltage ride through control strategy is generated;Finally, when determining that the voltage of power grid meets target condition, the output current characteristic selected in network energy storage low voltage ride through control strategy based on the limiting phase of current is used to simulate the operation of power generation equipment and control power grid, wherein the target condition at least includes voltage threshold, so as to realize the function of power system energy storage control.Compared with prior art, in the scheme of the application, it is no longer necessary to add virtual impedance control link for power grid as prior art, so that the problem of unsatisfactory limiting effect of output current in extreme transient time caused by virtual impedance does not exist, and in the present application, the influence of active power and reactive power is considered, and virtual impedance is not set, so the influence of virtual impedance parameter on low voltage ride through does not exist.Therefore, compared with prior art, in the present application, a low voltage ride through function for power grid based on virtual impedance is not needed, compared with the unsatisfactory limiting effect of output current in extreme transient time caused by setting virtual impedance and control, and the active power and reactive power output are greatly influenced by virtual impedance parameter, so the problem of difficult quantitative control in fault process is also avoided, so as to ensure that the present application is more effective and reliable compared with prior art.In addition, in the process of obtaining basic control architecture and determining virtual synchronous general control strategy in the power system energy storage control process of the present application, network energy storage system can simulate the operating characteristics of power generation equipment, such as inertia support and primary frequency modulation, which can enhance the stability of power grid, and in the process of analyzing the active and reactive output characteristics under current limiting condition, the active and reactive output characteristics of network energy storage under different current limiting phase can be determined by using vector diagram and quantitative calculation, which provides data support for subsequent control strategy.And, in determining the current limiting phase and output current characteristics and generating the control strategy, the current limiting phase and output current characteristics when triggering current limiting can be determined based on the analysis result through the ring current limiting controller, thereby laying a foundation for subsequent application of the control strategy when the grid voltage meets the target condition, and in addition, in the present application, when the grid voltage drops beyond the preset threshold and the current reaches the limit, the current limiting phase is adjusted, the grid-connected energy storage system outputs reactive power to support the voltage and does not output active power, which can help the grid to quickly recover stable operation.

[0159] The embodiment of the present application provides a storage medium, the storage medium comprising a stored program, wherein the device where the storage medium is located executes the power system energy storage control method when the program runs.

[0160] The storage medium can include a non-permanent memory in a computer readable medium, a random access memory (RAM) and / or a non-volatile memory such as a read-only memory (ROM) or a flash memory (flash RAM), and the memory includes at least one memory chip.

[0161] The embodiment of the present application further provides a power system energy storage control device, the device comprising a storage medium and one or more processors, the storage medium being coupled with the processor, the processor being configured to execute program instructions stored in the storage medium; the power system energy storage control method is executed when the program instructions run.

[0162] The embodiment of the present application provides a device, the device comprising a processor, a memory and a program stored in the memory and executable on the processor, and the processor implements the following steps when executing the program: obtaining a basic control architecture of a grid-connected energy storage, and determining a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, so as to simulate operation of a power generation device of a power grid based on the virtual synchronous general control strategy; based on the virtual synchronous general control strategy, analyzing and calculating active output characteristics and reactive output characteristics of the grid-connected energy storage under current limiting by using a vector diagram and active quantitative calculation and reactive quantitative calculation, to obtain an analysis result; based on the analysis result, determining a current limiting phase of each current and corresponding output current characteristics when the grid-connected energy storage triggers current limiting by using a ring current limiting controller in combination with current limiting factors of the grid-connected energy storage under a low voltage scenario of the power grid, and generating a low voltage ride through control strategy of the grid-connected energy storage; when it is determined that the grid voltage meets a target condition, simulating operation of the power generation device and controlling the power grid based on the output current characteristics selected in the low voltage ride through control strategy of the grid-connected energy storage based on the current limiting phase of the current, wherein the target condition at least comprises a voltage threshold.

[0163] Further, the basic control architecture of the grid-connected energy storage is acquired, and a virtual synchronous general control strategy of the grid-connected energy storage system is determined based on the basic control architecture, including:

[0164] An equivalent simplified grid-connected topology of the grid-connected energy storage system is acquired, and a control architecture of the controllable grid-connected inverter is determined. Based on the equivalent simplified grid-connected topology and the control architecture of the controllable grid-connected inverter, a corresponding virtual synchronous control general control architecture and a general control architecture control strategy are determined.

[0165] The generation operation equipment is simulated through the virtual synchronous control general control architecture and the general control architecture control strategy, a corresponding active synchronous ring control algorithm is set, the inverter output active power is adjusted according to the grid frequency deviation, and the voltage outer ring and the current inner ring are respectively independently adjusted by using a decoupling control algorithm, so as to determine a virtual synchronous active synchronous ring general control strategy and a double-loop decoupling general control strategy of the grid-connected inverter.

[0166] Further, based on the virtual synchronous general control strategy, vector diagrams and active and reactive quantitative calculations are used to analyze and calculate active and reactive output characteristics of the grid-connected energy storage under current limiting conditions, to obtain analysis results, including:

[0167] According to the current output characteristics of the grid-connected energy storage grid-connected converter under current limiting conditions, voltage vector diagrams and current vector diagrams of the grid under voltage drop after grid fault and disturbance are determined.

[0168] Through the change characteristics of the voltage vector diagram and the current vector diagram, a quantitative calculation method and an output characteristic description of the active and reactive output characteristics of the grid-connected energy storage under different current limiting phases are determined.

[0169] Further, the output current characteristics specifically include an output current characteristic description equation.

[0170] Based on the analysis results, through a ring current limiting controller, in combination with current limiting factors of the grid-connected energy storage under a low voltage scenario of the grid, a current limiting phase of each current and a corresponding output current characteristic when the grid-connected energy storage triggers current limiting are determined, and a low voltage ride through control strategy of the grid-connected energy storage is generated, including:

[0171] Based on the analysis results, a basic working principle of the ring current limiting controller is determined, and an output current characteristic description equation containing the current limiting phase of the current is determined under the action of the ring current limiting controller.

[0172] Based on the output current characteristic description equation, the output current corresponding to each current limiting phase is determined, and the low voltage ride through control strategy of the grid-connected energy storage is generated.

[0173] Further, when it is determined that the grid voltage meets the target condition, the output current characteristics selected in the grid-connected energy storage low-voltage ride-through control strategy based on the limited phase of the current at present simulate the operation of the power generation equipment and control the grid, comprising:

[0174] When it is determined that the voltage drop depth exceeds the preset threshold value and the output current of the grid-connected energy storage grid-connected inverter reaches the current limit, it is determined that the grid voltage meets the target condition;

[0175] When the grid voltage meets the target condition, the limited phase of the current and the corresponding output current are adjusted in real time based on the grid-connected energy storage low-voltage ride-through control strategy, so that the grid-connected energy storage system does not output active power and fully outputs reactive power when the grid voltage meets the target condition, so as to improve the reactive voltage support capability of the grid-connected energy storage and perform low-voltage ride-through.

[0176] Further, the real-time adjustment of the limited phase of the current and the corresponding output current based on the grid-connected energy storage low-voltage ride-through control strategy comprises:

[0177] Based on the grid-connected energy storage low-voltage ride-through control strategy, the value of the limited phase of the current is dynamically adjusted, so that the angle between the output voltage vector of the grid-connected energy storage and the current vector is kept within a preset range, so that the grid-connected energy storage system provides reactive voltage support for the grid.

[0178] Further, the virtual synchronous general control strategy specifically comprises a virtual synchronous active synchronous ring control strategy of the grid-connected inverter and a double-loop decoupling control strategy of the voltage outer loop and the current inner loop;

[0179] The virtual synchronous active synchronous ring control strategy of the grid-connected inverter is used to simulate the swing characteristics of the synchronous generator and determine the dq axis phase in the current coordinate system accordingly; the double-loop decoupling control strategy of the voltage outer loop and the current inner loop is specifically used to generate the PWM control signal of the grid-connected energy storage grid-connected inverter through the cascade control of the voltage outer loop and the current inner loop.

[0180] The application further provides a computer program product suitable for executing program code for initializing the following method steps when executed on a data processing device: obtaining a basic control framework of grid-connected energy storage, and determining a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control framework, so as to simulate operation of power generation equipment of a power grid based on the virtual synchronous general control strategy; based on the virtual synchronous general control strategy, analyzing and calculating active power output characteristics and reactive power output characteristics of the grid-connected energy storage under current limiting conditions by using vector diagrams and active power quantitative calculation and reactive power quantitative calculation, to obtain analysis results; based on the analysis results, determining a limiting phase of each current and corresponding output current characteristics of the grid-connected energy storage when current limiting is triggered by the grid-connected energy storage, in combination with current limiting factors of the grid-connected energy storage under a low-voltage scenario of the power grid through a ring current limiting controller, and generating a low-voltage ride-through control strategy of the grid-connected energy storage; and when it is determined that the voltage of the power grid meets a target condition, simulating operation of the power generation equipment and controlling the power grid based on the output current characteristics selected in the low-voltage ride-through control strategy of the grid-connected energy storage according to the limiting phase of the current, wherein the target condition at least includes a voltage threshold.

[0181] Those skilled in the art will understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) containing computer-usable program code. The present application is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions, which are executed via the processor of the computer or other programmable data processing apparatus, generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 one or more flows and / or blocks Figure 1 one or more flows and / or blocks Figure 1 one or more flows and / or blocks

[0182] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 Figure 1

[0183] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0184] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can execute instructions. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other memory technologies, about which the processor can execute instructions. The memory is an example of computer readable media.

[0185] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EEPROM), flash memory or other memory technologies, compact disc read only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0186] It should also be noted that the terms "comprising", "comprises", "including", "includes" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0187] ​​Those skilled in the art will appreciate that embodiments of the present application can be devised for a method, a system, or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer-readable program code thereon for use by or in connection with an instruction execution system. For the purposes of this description, a computer-usable or computer readable storage medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. The computer-usable or computer readable program code can be downloaded from an Internet website, server, or other remote source via a network or a data stream communication path. From the Internet website, server, or other remote source, the code can be downloaded into the instruction execution system, apparatus, or device where execution of the same can take place. The present application is directed to any number and type of computer-usable storage media, apparatuses, and devices self-evidently known to one of ordinary skill in the art.

[0188] The foregoing is merely illustrative of the principles of the application, and various modifications can be made by those skilled in the art without departing from the scope of the application. The depicted embodiments are to be considered in all respects only as illustrative, and not restrictive.

Claims

1. A power system energy storage control method, characterized by, The method comprises: acquiring a basic control architecture of grid-connected energy storage, and determining a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, so as to simulate operation of power generation equipment of the power grid based on the virtual synchronous general control strategy; based on the virtual synchronous general control strategy, using vector diagrams and active quantitative calculation and reactive quantitative calculation, analyzing and calculating active output characteristics and reactive output characteristics of the grid-connected energy storage under current limiting conditions to obtain analysis results; based on the analysis results, determining, through a ring current limiting controller, a limiting phase of each current and corresponding output current characteristics of the grid-connected energy storage when current limiting is triggered in combination with current limiting factors of the grid-connected energy storage under a low voltage scenario of the power grid, and generating a low voltage ride through control strategy of the grid-connected energy storage; when it is determined that the voltage of the power grid meets a target condition, simulating operation of the power generation equipment and controlling the power grid based on output current characteristics selected in the low voltage ride through control strategy of the grid-connected energy storage based on the limiting phase of the current, wherein the target condition at least comprises a voltage threshold.

2. The method of claim 1, wherein, The acquiring a basic control architecture of grid-connected energy storage, and determining a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, comprises: acquiring an equivalent simplified grid-connected topology of the grid-connected energy storage system, and determining a control architecture of a controllable grid-connected inverter, based on the equivalent simplified grid-connected topology and the control architecture of the controllable grid-connected inverter, determining a corresponding virtual synchronous control general control architecture and a general control architecture control strategy; simulating operation of the power generation equipment through the virtual synchronous control general control architecture and the general control architecture control strategy, setting a corresponding active synchronous ring control algorithm, adjusting the output active power of the inverter according to the frequency deviation of the power grid, and then independently adjusting the voltage outer ring and the current inner ring by using a decoupling control algorithm to determine a virtual synchronous active synchronous ring general control strategy and a double-loop decoupling general control strategy of the grid-connected inverter.

3. The method of claim 1, wherein, The based on the virtual synchronous general control strategy, using vector diagrams and active quantitative calculation and reactive quantitative calculation, analyzing and calculating active output characteristics and reactive output characteristics of the grid-connected energy storage under current limiting conditions to obtain analysis results, comprises: determining voltage vector diagrams and current vector diagrams of the power grid when the voltage of the power grid drops after a power grid fault and disturbance according to current output characteristics of the grid-connected energy storage grid-connected converter under current limiting conditions; determining quantitative calculation methods and output characteristic descriptions of active output characteristics and reactive output characteristics of the grid-connected energy storage under limiting phases of different currents through the change characteristics of the voltage vector diagrams and the current vector diagrams.

4. The method of claim 3, wherein, The output current characteristics specifically comprise output current characteristic description equations; The based on the analysis results, determining, through a ring current limiting controller, a limiting phase of each current and corresponding output current characteristics of the grid-connected energy storage when current limiting is triggered in combination with current limiting factors of the grid-connected energy storage under a low voltage scenario of the power grid, and generating a low voltage ride through control strategy of the grid-connected energy storage, comprises: based on the analysis results, determining a basic working principle of the ring current limiting controller, and determining output current characteristic description equations containing the limiting phase of the current under the action of the ring current limiting controller; Determine the output current corresponding to the current limiting phase of each current based on the output current characteristic equation, and generate the grid-connected energy storage low voltage ride through control strategy.

5. The method of claim 1, wherein, When it is determined that the grid voltage meets the target condition, simulate the operation of the power generation equipment and control the grid based on the output current characteristic of the current limiting phase of the current selected in the grid-connected energy storage low voltage ride through control strategy, including: When it is determined that the voltage drop depth exceeds the preset threshold and the output current of the grid-connected energy storage inverter reaches the current limit, it is determined that the grid voltage meets the target condition; When the grid voltage meets the target condition, adjust the current limiting phase and the corresponding output current in real time based on the grid-connected energy storage low voltage ride through control strategy, so that the grid-connected energy storage system does not output active power and outputs full reactive power when the grid voltage meets the target condition, so as to improve the reactive voltage support capability of the grid-connected energy storage for low voltage ride through.

6. The method of claim 5, wherein, The real-time adjustment of the current limiting phase and the corresponding output current based on the grid-connected energy storage low voltage ride through control strategy includes: Based on the grid-connected energy storage low voltage ride through control strategy, dynamically adjust the value of the current limiting phase to keep the angle between the output voltage vector and the current vector of the grid-connected energy storage within a preset range, so that the grid-connected energy storage system provides reactive voltage support for the grid.

7. The method of claim 1, wherein, The virtual synchronous general control strategy specifically includes a virtual synchronous active synchronous ring control strategy of the grid-connected inverter and a double-loop decoupling control strategy of the voltage outer loop and the current inner loop. The virtual synchronous active synchronous ring control strategy of the grid-connected inverter is used to simulate the swing characteristics of the synchronous generator and determine the dq axis phase in the current coordinate system; the double-loop decoupling control strategy of the voltage outer loop and the current inner loop is specifically used to generate the PWM control signal of the grid-connected energy storage inverter through the cascade control of the voltage outer loop and the current inner loop.

8. An energy storage control device for a power system, characterized by The device includes: A determination unit is configured to obtain a basic control architecture of the grid-connected energy storage, and determine a virtual synchronous general control strategy of the grid-connected energy storage system based on the basic control architecture, so as to simulate the operation of the power generation equipment of the grid based on the virtual synchronous general control strategy; An analysis unit is configured to analyze and calculate the active output characteristic and the reactive output characteristic of the grid-connected energy storage under current limiting based on the virtual synchronous general control strategy, using vector diagrams and active and reactive quantitative calculations, to obtain analysis results; A generation unit is configured to determine the current limiting phase of each current and the corresponding output current characteristic when the grid-connected energy storage triggers current limiting based on the analysis results, through a ring current limiting controller, in combination with the current limiting factors of the grid-connected energy storage in the low voltage scenario of the grid, and generate a grid-connected energy storage low voltage ride through control strategy; An execution unit is configured to simulate the operation of the power generation equipment and control the grid based on the output current characteristic of the current selected in the grid-connected energy storage low voltage ride through control strategy based on the current limiting phase of the current when it is determined that the grid voltage meets the target condition, wherein the target condition at least includes a voltage threshold.

9. A storage medium, characterized by The storage medium includes a stored program, wherein the program, when executed, controls a device in which the storage medium is located to perform the power system energy storage control method of any one of claims 1 to 7.

10. An energy storage control device for an electric power system, characterized by The apparatus includes a storage medium and one or more processors, the storage medium being coupled to the processors, the processors being configured to execute program instructions stored in the storage medium, and the program instructions, when executed, perform the power system energy storage control method of any one of claims 1 to 7.

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