Method for improving grid frequency using energy storage system and related apparatus

Abstract

The application provides a method for improving grid frequency by using an energy storage system and a related device. The energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter. The method comprises: controlling the energy storage converter and the inverter by using a VSG control method respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency. The above method considers the characteristics of the flywheel energy storage module as a rotating system, so the response speed is fast. The VSG control of the flywheel energy storage module on the corresponding inverter compensates for the slow response speed of the photovoltaic energy storage VSG of the non-rotating system, so as to jointly provide virtual inertia for the grid and improve the stability of the grid frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage systems, and particularly relates to a method for improving grid frequency by using an energy storage system and a related device. BACKGROUND

[0002] Synchronous generators provide a large amount of mechanical inertia for the grid, can be naturally coupled with the grid, participate in the regulation of grid voltage and frequency, and when a power system fault occurs, the mechanical inertia of the synchronous generator can provide sufficient rotating reserve capacity to make up for the power loss. With the increasing proportion of grid-connected photovoltaic energy storage systems, the proportion of synchronous generators in the power system is also decreasing.

[0003] In order to make up for the lack of voltage and frequency regulation capability brought by grid-connected photovoltaic energy storage systems, the prior art usually uses VSG (Virtual Synchronous Generator) to embed the rotor motion equation of the synchronous generator and the reactive power droop control algorithm into the inverter control system, so as to adjust the distributed power generation of the inverter control system when the grid is subjected to faults or disturbances, and realize the working characteristics similar to the synchronous generator. Although the photovoltaic energy storage VSG can increase the virtual inertia for the grid, the response speed is slow, and the improvement effect on the stability of the power system is not good. SUMMARY

[0004] The embodiments of the present application provide a method for improving grid frequency by using an energy storage system and a related device, to solve the problem that the existing photovoltaic energy storage VSG has poor improvement effect on the stability of the power system.

[0005] In a first aspect, the embodiments of the present application provide a method for improving grid frequency by using an energy storage system, wherein the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter; the target energy storage module is connected with a grid bus through the energy storage converter, and the flywheel energy storage module is connected with the grid bus through the rectifier and the inverter in sequence.

[0006] The method comprises:

[0007] The energy storage converter and the inverter are controlled by using a VSG control method respectively, so as to jointly provide virtual rotor inertia by the energy storage converter and the inverter, and maintain the stability of the grid frequency.

[0008] In a second aspect, the embodiments of the present application provide a device for improving grid frequency by using an energy storage system, wherein the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier and an inverter; the target energy storage module is connected with a grid bus through the energy storage converter, and the flywheel energy storage module is connected with the grid bus through the rectifier and the inverter in sequence.

[0009] The device comprises:

[0010] A VSG control module is configured to control the energy storage converter and the inverter respectively by using a VSG control method, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency.

[0011] In a third aspect, an embodiment of the present application provides a terminal, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method for improving the grid frequency by using the energy storage system according to any possible implementation manner of the first aspect.

[0012] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executable on a processor to implement the steps of the method for improving the grid frequency by using the energy storage system according to any possible implementation manner of the first aspect.

[0013] In a fifth aspect, an embodiment of the present application provides an energy storage system, which comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter, and the terminal according to the third aspect.

[0014] The target energy storage module is connected with a grid bus through the energy storage converter, and the flywheel energy storage module is connected with the grid bus through the rectifier, the inverter, and the energy storage converter in sequence.

[0015] The embodiment of the present application provides a method for improving the grid frequency by using an energy storage system, and related devices, the energy storage system comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and an inverter, and a VSG control method is used to control the energy storage converter and the inverter respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency. The above method considers the characteristics that the flywheel energy storage module is a rotating system and has a fast response speed, and compensates for the slow response speed of the photovoltaic energy storage VSG of the non-rotating system through the VSG control of the flywheel energy storage module on the inverter, so as to jointly provide virtual inertia for the grid and improve the stability of the grid frequency. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0017] Figure 1 is an application scenario of the method for improving grid frequency by using an energy storage system provided by the embodiment of the present application;

[0018] Figure 2 is a flowchart of the method for improving grid frequency by using an energy storage system provided by the embodiment of the present application;

[0019] Figure 3 is a VSG control flowchart provided by the embodiment of the present application;

[0020] Figure 4 is an SPWM signal generation flowchart provided by the embodiment of the present application;

[0021] Figure 5 is a structural schematic diagram of the device for improving grid frequency by using an energy storage system provided by the embodiment of the present application;

[0022] Figure 6 is a schematic diagram of a terminal provided by the embodiment of the present application. DETAILED DESCRIPTION

[0023] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known structures, devices, circuits, and methods have not been described in detail in order to avoid obscuring the present application.

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will be described by specific embodiments in conjunction with the accompanying drawings.

[0025] Figure 1 is an application scenario of the method for improving grid frequency by using an energy storage system provided by the embodiment of the present application. As shown in Figure 1 the energy storage system includes a target energy storage module BAT, flywheel energy storage modules M (M1, M2,..., MN), energy storage converters PCS (PCS1, PCS2,..., PCSn), a rectifier AC / DC and an inverter DC / AC; the target energy storage module BAT is connected with a grid bus through the energy storage converter PCS, and the flywheel energy storage modules M are connected with the grid bus through the rectifier AC / DC and the inverter DC / AC in sequence.

[0026] Specifically, the target energy storage module is an energy storage module other than a flywheel energy storage module, and can specifically include a photovoltaic energy storage module, a wind power energy storage module, or an energy storage battery. When the target energy storage module is a photovoltaic energy storage module, the target energy storage module includes a photovoltaic polar plate, a DCDC module, and a battery module, and the photovoltaic polar plate is connected to one end of the DCDC module, and the other end of the DCDC module is connected to an output end of the target energy storage module and the battery module, respectively. The method provided in the present application is described in detail below by taking the photovoltaic energy storage module as an example.

[0027] Referring to Figure 2 which shows an implementation flowchart of the method for improving grid frequency by using an energy storage system according to an embodiment of the present application, and is described in detail as follows:

[0028] S101: The VSG control method is used to control the energy storage converter and the inverter, respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency.

[0029] The execution subject of the present embodiment is a control host of an energy storage system, which is in communication connection with a controller of an energy storage converter and a controller of an inverter, respectively, and is used to issue a virtual rotor inertia distribution instruction to the controller of the energy storage converter and the controller of the inverter, respectively. The controller of the energy storage converter and the controller of the inverter perform corresponding VSG control on the corresponding circuits based on the respective received virtual rotor inertia distribution instructions, so that the energy storage converter VSG and the inverter VSG output the virtual rotor inertia corresponding to the virtual rotor inertia distribution instruction.

[0030] In the present embodiment, the virtual synchronous machine technology is a technology for making the power supply or load using a converter have the inertia, damping, frequency and voltage adjustment and other operating external characteristics of a synchronous machine set by simulating the electromechanical transient characteristics of the synchronous machine set. Since the photovoltaic energy storage system is a non-rotating system, the speed of the corresponding virtual synchronous generator in responding to the change of the grid frequency is slow, and therefore the grid frequency cannot be adjusted in time when the grid fluctuation is large. In the primary frequency control stage of the present embodiment, the flywheel energy storage module is connected to the grid, which will not cause further fluctuation of the grid, and can compensate for the slow response speed of the photovoltaic energy storage VSG of the non-rotating system, so that the flywheel energy storage VSG and the photovoltaic energy storage VSG jointly provide virtual inertia for the grid when the grid frequency fluctuation is large, so that the grid frequency quickly reaches stability.

[0031] In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; and the specific implementation process of S101 includes:

[0032] The first virtual rotor inertia is set as a fixed value;

[0033] determine a second virtual rotor inertia based on the grid frequency;

[0034] control the energy storage converter using the first virtual rotor inertia and control the inverter using the second virtual rotor inertia.

[0035] In one possible implementation, the specific implementation process of determining the virtual rotor inertia demand value includes:

[0036] based on the formula calculate the second virtual rotor inertia;

[0037] wherein J represents the second virtual rotor inertia, J0 represents a virtual rotor inertia steady-state value, ω represents a virtual rotor angular velocity of the inverter, ω g represents a grid angular velocity, and ω g = 2πf g wherein f g represents the grid frequency, and k represents a constant, and C represents a threshold value of a virtual rotor angular velocity change rate.

[0038] Specifically, the size of the virtual rotor inertia is determined by the difference between the virtual angular velocity of the VSG and the grid angular velocity, and the size of the virtual angular velocity rate. When the virtual angular velocity of the VSG is greater than the grid angular velocity, and the virtual angular velocity rate of the VSG is greater than zero, the virtual rotor inertia will increase. When the virtual angular velocity of the VSG is greater than the grid angular velocity, and the virtual angular velocity rate of the VSG is less than zero, the virtual rotor inertia will decrease. When the virtual angular velocity of the VSG is less than the grid angular velocity, and the virtual angular velocity rate of the VSG is less than zero, the virtual rotor inertia will increase. When the virtual angular velocity of the VSG is less than the grid angular velocity, and the virtual angular velocity rate of the VSG is greater than zero, the virtual rotor inertia will decrease. Based on the above principle, the energy storage converter VSG / inverter VSG can adaptively output a corresponding size of virtual rotor inertia based on the grid frequency, thereby improving the frequency response speed of the energy storage system.

[0039] wherein J0 represents a virtual rotor inertia steady-state value, which can be determined based on the natural vibration angular velocity of the synchronous generator.

[0040] As can be seen from the above embodiment, when the grid system is relatively stable, the original target energy storage module corresponding to the VSG of the inverter is used to stabilize the grid frequency. When the grid frequency fluctuates greatly, based on the advantages of fast response speed of the adaptive virtual rotor inertia method and the fact that the flywheel energy storage system itself has a fast response speed, the flywheel energy storage provides virtual rotor inertia to fine-tune the grid frequency on the basis of the photovoltaic energy storage VSG, thereby not only taking full advantage of the fast response speed of the flywheel energy storage VSG, but also not needing to configure a large-capacity flywheel energy storage module.

[0041] In a possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the specific implementation process of S101 includes:

[0042] The second virtual rotor inertia is set as a fixed value;

[0043] The first virtual rotor inertia is adaptively determined based on the grid frequency;

[0044] The energy storage converter is controlled by using the first virtual rotor inertia, and the inverter is controlled by using the second virtual rotor inertia.

[0045] The embodiment can assign a fixed virtual rotor inertia to the inverter VSG corresponding to the flywheel energy storage module, and make the target energy storage module provide a virtual rotor inertia that adaptively changes with the grid frequency, so as to simultaneously improve the response speed of the VSGs corresponding to the flywheel energy storage module and the target energy storage module, and further improve the grid frequency stability.

[0046] Specifically, when the first virtual rotor inertia is adaptively determined based on the grid frequency, the formula is ω = ω 0 + K f f, where ω is the virtual rotor angular velocity of the energy storage converter.

[0047] In a possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia;

[0048] The specific implementation process of S101 includes:

[0049] The second virtual rotor inertia corresponding to the inverter is adaptively obtained based on the grid frequency;

[0050] If the second virtual rotor inertia is smaller than the first rotor inertia maximum value, the first virtual rotor inertia is set as zero;

[0051] If the second virtual rotor inertia is equal to the first rotor inertia maximum value, the first virtual rotor inertia corresponding to the energy storage converter is adaptively obtained based on the grid frequency;

[0052] The energy storage converter is controlled by using the first virtual rotor inertia, and the inverter is controlled by using the second virtual rotor inertia.

[0053] ​Specifically, the embodiment can preferentially use the virtual rotor inertia provided by the inverter VSG to support the grid frequency, so as to improve the response speed. When the inverter VSG is insufficient to support the grid frequency, the energy storage converter is enabled to provide the virtual rotor inertia adaptive to the grid frequency. The size of the virtual rotor angular velocity is positively correlated with the size of the input power of the inverter, and therefore the maximum value of the first rotor inertia corresponding to the inverter is the virtual rotor inertia output when the maximum overload capacity of the inverter is reached.

[0054] In the embodiment, the control host determines that the inverter cannot output the virtual inertia sufficient to support the grid frequency when it is monitored that the second virtual rotor inertia is equal to the maximum value of the first rotor inertia for a first preset time duration or the number of sampling time points at which the second virtual rotor inertia is equal to the maximum value of the first rotor inertia accounts for a preset percentage of the total number of sampling time points in a second preset time duration. The first virtual rotor inertia corresponding to the energy storage converter is adaptively acquired based on the grid frequency.

[0055] The preset percentage can be 60% to 80%.

[0056] In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia. The specific implementation process of S101 includes:

[0057] The first virtual rotor inertia corresponding to the energy storage converter is adaptively acquired based on the grid frequency.

[0058] If the first virtual rotor inertia is less than the maximum value of the second rotor inertia, the second virtual rotor inertia is set to zero.

[0059] If the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, the second virtual rotor inertia corresponding to the energy storage converter is adaptively acquired based on the grid frequency.

[0060] The energy storage converter is controlled by using the first virtual rotor inertia, and the inverter is controlled by using the second virtual rotor inertia.

[0061] Specifically, the embodiment can preferentially use the virtual rotor inertia provided by the energy storage converter to support the grid frequency, and when the energy storage converter VSG is insufficient to support the grid frequency, the inverter is enabled to provide the virtual rotor inertia adaptive to the grid frequency, so that the grid frequency can be stabilized without configuring a large-capacity flywheel energy storage module. The size of the virtual rotor angular velocity is positively correlated with the size of the input power of the energy storage converter, and therefore the maximum value of the second rotor inertia corresponding to the energy storage converter is the virtual rotor inertia output when the maximum overload capacity of the energy storage converter is reached.

[0062] In this embodiment, if the control host detects that the first virtual rotor inertia is equal to the maximum value of the second rotor inertia for a first preset duration, or if the number of control cycles in which the first virtual rotor inertia is equal to the maximum value of the second rotor inertia within a second preset duration accounts for a preset percentage of the total number of control cycles in the second preset duration, then it determines that the energy storage converter cannot output a virtual inertia sufficient to support the grid frequency, and then adaptively obtains the second virtual rotor inertia corresponding to the inverter based on the grid frequency.

[0063] In one possible implementation Figure 3 The control flowchart of the energy storage converter is shown, such as... Figure 3 As shown, the specific implementation process of using the first virtual rotor inertia to perform VSG control on the energy storage converter includes:

[0064] S201: Convert the actual input voltage value U of the energy storage converter o Input reactive power-voltage regulation loop, output given VSG voltage amplitude e of energy storage converter. a ,e b ,e c ;

[0065] S202: Input the active power P of the energy storage converter into the active-frequency regulation loop, and output the phase of VSG. The first virtual rotor inertia is a parameter value in the active-frequency regulation loop;

[0066] S203: Based on the given VSG voltage amplitude e of the energy storage converter a ,e b ,e c Phase with VSG The three-phase setpoint voltages of the energy storage converter VSG are obtained.

[0067] Specifically, the implementation process of S201 includes:

[0068] Obtain the actual input voltage U of the energy storage converter o ;

[0069] Input voltage rating U ref Subtract the actual input voltage U o The input voltage error is obtained;

[0070] Given reactive power Q ref Subtracting the output reactive power Q of the energy storage converter after the amplitude limit is used to obtain the reactive power error;

[0071] Input voltage error and voltage regulation coefficient k v Multiply by the first control variable to obtain the reactive power error and the reactive power adjustment coefficient k. qMultiply them to obtain the second control variable;

[0072] The first control value, the second control value, and the no-load electromotive force E0 of the energy storage converter VSG are added together to obtain the given voltage amplitude e of the energy storage converter VSG. a ,e b ,e c ;

[0073] Specifically, such as Figure 3 As shown, the specific implementation process of S202 includes:

[0074] Given active power P ref Subtract the input active power P of the energy storage converter to obtain the active power difference;

[0075] Based on formula Calculate the virtual rotor angular velocity ω of the VSG; integrate the virtual rotor angular velocity ω of the VSG to obtain the phase of the VSG.

[0076] Where ω0 represents the grid synchronization angular velocity, D represents the damping coefficient corresponding to the damping torque, and T d This is the damping torque derived from mechanical friction, stator losses, excitation, and damping windings.

[0077] In one possible implementation, the specific implementation process of S203 includes:

[0078] Based on formula

[0079]

[0080] Calculate the three-phase setpoint voltage of the energy storage converter VSG;

[0081] In equation (1), e a Represents the given voltage of phase a, e b This represents the given voltage of phase b, e c E represents the given voltage of phase c. p This represents the amplitude of the phase voltage, where E represents the given amplitude of the VSG voltage of the energy storage converter. ω represents the phase of the VSG, and ω represents the angular velocity of the virtual rotor.

[0082] In one possible implementation Figure 4 A flowchart illustrating the generation process of the SPWM (Sinusoidal Pulse Width Modulation) signal for controlling the energy storage converter is shown. Figure 4 As shown, after obtaining the three-phase setpoint voltage of the energy storage converter, the three-phase setpoint voltage is input... Figure 4 The control loop shown generates an SPWM signal. Figure 4wherein i ref represents the rated grid-connected current, i a represents the rated grid-connected current, i b represents the rated grid-connected current, i c represents the rated grid-connected current, i e represents the output current deviation; PR is a proportional resonant regulator, L represents inductance, R represents local resistance, u m represents the voltage amplitude of the modulation signal.

[0083] In the embodiment, after obtaining the sinusoidal pulse width modulation signal, the sinusoidal pulse width modulation signal is used to control the switches of the energy storage converter, so that the energy storage converter outputs corresponding virtual rotor inertia.

[0084] Similarly, the VSG control of the inverter and the generation of the sinusoidal pulse width modulation signal can also be implemented by using the control block diagrams shown in Figure 3 and Figure 4 Here, no further description is given.

[0085] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0086] The following is a device embodiment of the application, and for details not described in detail, reference can be made to the corresponding method embodiments described above.

[0087] Figure 5 A structure schematic diagram of a device for improving grid frequency by using an energy storage system is shown, only parts related to the embodiments of the application are shown for the convenience of description, and the details are as follows:

[0088] As shown in Figure 5 , the device for improving grid frequency by using an energy storage system 100 comprises:

[0089] A VSG control module 110 is configured to control the energy storage converter and the inverter by using a VSG control method, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency.

[0090] In one possible implementation, the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 comprises:

[0091] A first virtual rotor inertia acquisition unit is configured to set the first virtual rotor inertia as a fixed value.

[0092] a second virtual rotor inertia obtaining unit configured to adaptively determine a second virtual rotor inertia based on the grid frequency;

[0093] a VSG control unit configured to perform VSG control on the energy storage converter using the first virtual rotor inertia and perform VSG control on the inverter using the second virtual rotor inertia.

[0094] In one possible implementation, the second virtual rotor inertia obtaining unit comprises:

[0095] calculating the second virtual rotor inertia based on the formula

[0096] wherein J represents the second virtual rotor inertia, J0 represents a steady-state value of the virtual rotor inertia, ω represents a virtual rotor angular velocity of the inverter, ω g represents a grid angular velocity, and ω g = 2πf g wherein f g represents the grid frequency, and k represents a constant, and C represents a threshold value of a virtual rotor angular velocity change rate.

[0097] In one possible implementation, the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia, and the VSG control module 110 comprises:

[0098] setting the second virtual rotor inertia as a fixed value;

[0099] adaptively determining the first virtual rotor inertia based on the grid frequency;

[0100] performing VSG control on the energy storage converter using the first virtual rotor inertia and performing VSG control on the inverter using the second virtual rotor inertia.

[0101] In one possible implementation, the virtual rotor inertia comprises a first virtual rotor inertia and a second virtual rotor inertia, and the VSG control module 110 comprises:

[0102] adaptively obtaining a second virtual rotor inertia corresponding to the inverter based on the grid frequency;

[0103] if the second virtual rotor inertia is less than a first rotor inertia maximum value, setting the first virtual rotor inertia as zero;

[0104] if the second virtual rotor inertia is equal to the first rotor inertia maximum value, adaptively obtaining a first virtual rotor inertia corresponding to the energy storage converter based on the grid frequency;

[0105] ​The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter.

[0106] In one possible implementation, the virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; the VSG control module 110 includes:

[0107] The first virtual rotor inertia of the energy storage converter is obtained adaptively based on the grid frequency.

[0108] If the first virtual rotor inertia is less than the maximum value of the second rotor inertia, then the second virtual rotor inertia is set to zero.

[0109] If the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, then the second virtual rotor inertia corresponding to the energy storage converter is obtained adaptively based on the grid frequency.

[0110] The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter.

[0111] As can be seen from the above embodiments, the above device takes into account the characteristics of the flywheel energy storage module as a rotating system, so the response speed is fast. It compensates for the disadvantage of the slow response speed of the photovoltaic energy storage system in the non-rotating system by using the VSG control of the inverter corresponding to the flywheel energy storage module, thereby jointly providing virtual inertia for the power grid and improving the stability of the power grid frequency.

[0112] Figure 6 This is a schematic diagram of a terminal provided in an embodiment of the present invention. Figure 6 As shown, the terminal 6 in this embodiment includes a processor 60 and a memory 61. The memory 61 stores a computer program 62, and the processor 60 calls and runs the computer program 62 stored in the memory 61 to execute the steps in the various embodiments of the method for improving grid frequency using energy storage systems, for example... Figure 2 Step 101 is shown. Alternatively, the processor 60 is used to call and run the computer program 62 stored in the memory 61 to implement the functions of each module / unit in the above-described device embodiments, for example... Figure 5 The function of module 110 shown.

[0113] For example, the computer program 62 can be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 62 in the terminal 6.

[0114] The terminal 6 can be a desktop computer, a notebook computer, a palm computer, a cloud server, and the like. The terminal 6 can include, but is not limited to, a processor 60, a memory 61. Those skilled in the art can understand that the terminal 6 can include more or less components, or combine some components, or different components, for example, the terminal can also include an input / output device, a network access device, a bus, and the like. Figure 6 The terminal 6 is only an example and does not constitute a limitation on the terminal 6, and can include more or less components, or combine some components, or different components, for example, the terminal can also include an input / output device, a network access device, a bus, and the like.

[0115] The processor 60 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and the like. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0116] The memory 61 can be an internal storage unit of the terminal 6, for example, a hard disk or a memory of the terminal 6. The memory 61 can also be an external storage device of the terminal 6, for example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, and the like. Further, the memory 61 can include both the internal storage unit and the external storage device of the terminal 6. The memory 61 is used to store the computer program and other programs and data required by the terminal. The memory 61 can also be used to temporarily store data that has been output or will be output.

[0117] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is taken as an example, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0118] The energy storage system provided in the embodiment of the application comprises a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter and a terminal as described above.

[0119] The target energy storage module is connected with a power grid bus through the energy storage converter, and the flywheel energy storage module is connected with the power grid bus through the rectifier and the inverter in sequence.

[0120] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0121] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.

[0122] In the embodiments provided in the application, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are only schematic, for example, the division of the modules or units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed mutual units can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0124] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0125] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the above embodiments of the method for improving grid frequency using energy storage systems. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately added to or subtracted from the content as required by the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium may not include electrical carrier signals and telecommunication signals.

[0126] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for improving power grid frequency using an energy storage system, characterized in that, The energy storage system includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and an inverter; the target energy storage module is connected to the grid bus through the energy storage converter, and the flywheel energy storage module is connected to the grid bus in sequence through the rectifier and the inverter; The method includes: The VSG control method is used to control the energy storage converter and the inverter respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency; The virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; The method of using VSG control to control the energy storage converter and the inverter respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency, includes: Set the first virtual rotor inertia to a fixed value; The second virtual rotor inertia is adaptively determined based on the power grid frequency; The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter; Alternatively, the method of using VSG control to separately control the energy storage converter and the inverter, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency, includes: Set the second virtual rotor inertia to a fixed value; The first virtual rotor inertia is adaptively determined based on the power grid frequency; The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter; Alternatively, the method of using VSG control to separately control the energy storage converter and the inverter, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency, includes: The second virtual rotor inertia of the inverter is obtained adaptively based on the grid frequency. If the second virtual rotor inertia is less than the maximum value of the first rotor inertia, then the first virtual rotor inertia is set to zero. If the second virtual rotor inertia is equal to the maximum value of the first rotor inertia, then the first virtual rotor inertia corresponding to the energy storage converter is obtained adaptively based on the grid frequency. The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter.

2. The method for improving grid frequency using an energy storage system according to claim 1, characterized in that, The adaptive determination of the second virtual rotor inertia based on the power grid frequency includes: Based on formula Calculate the second virtual rotor inertia; in, J This represents the second virtual rotor inertia. J 0 represents the steady-state value of the virtual rotor inertia; This represents the virtual rotor angular velocity of the inverter. Represents the angular velocity of the power grid, and ,in, Indicates the frequency of the power grid. k Represents a constant. C The threshold representing the rate of change of the virtual rotor angular velocity.

3. The method for improving grid frequency using an energy storage system according to claim 1, characterized in that, The method of using VSG control to control the energy storage converter and the inverter respectively, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency, includes: The first virtual rotor inertia of the energy storage converter is obtained adaptively based on the grid frequency. If the first virtual rotor inertia is less than the maximum value of the second rotor inertia, then the second virtual rotor inertia is set to zero. If the first virtual rotor inertia is equal to the maximum value of the second rotor inertia, then the second virtual rotor inertia corresponding to the energy storage converter is obtained adaptively based on the grid frequency. The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter.

4. A device for improving grid frequency using an energy storage system, characterized in that, include: The energy storage system includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and an inverter; The target energy storage module is connected to the grid bus via the energy storage converter, and the flywheel energy storage module is connected to the grid bus in sequence via the rectifier and the inverter. The device includes: The VSG control module is used to control the energy storage converter and the inverter respectively using the VSG control method, so that the energy storage converter and the inverter jointly provide virtual rotor inertia to maintain the stability of the grid frequency; The virtual rotor inertia includes a first virtual rotor inertia and a second virtual rotor inertia; The VSG control module includes: Set the first virtual rotor inertia to a fixed value; The second virtual rotor inertia is adaptively determined based on the power grid frequency; The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter; Alternatively, the VSG control module includes: Set the second virtual rotor inertia to a fixed value; The first virtual rotor inertia is adaptively determined based on the power grid frequency; The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter; Alternatively, the VSG control module includes: The second virtual rotor inertia of the inverter is obtained adaptively based on the grid frequency. If the second virtual rotor inertia is less than the maximum value of the first rotor inertia, then the first virtual rotor inertia is set to zero. If the second virtual rotor inertia is equal to the maximum value of the first rotor inertia, then the first virtual rotor inertia corresponding to the energy storage converter is obtained adaptively based on the grid frequency. The first virtual rotor inertia is used to perform VSG control on the energy storage converter, and the second virtual rotor inertia is used to perform VSG control on the inverter.

5. A terminal, characterized in that, It includes a processor and a memory, the memory being used to store a computer program, and the processor being used to call and run the computer program stored in the memory to perform the method of improving grid frequency using an energy storage system as described in any one of claims 1 to 3.

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for improving grid frequency using an energy storage system as described in any one of claims 1 to 3 above.

7. An energy storage system, characterized in that, It includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, an inverter, and a terminal as described in claim 5; The target energy storage module is connected to the grid bus via the energy storage converter, and the flywheel energy storage module is connected to the grid bus in sequence via the rectifier and the inverter.

Images