VSG control method of energy storage system and related device

Abstract

The application provides a VSG control method of 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 and a rectifier. The output end of the target energy storage module is connected with the direct current end of the energy storage converter. The output end of the energy storage converter is connected with a power grid bus. The output end of the flywheel energy storage module is connected with the alternating current end of the rectifier. The direct current end of the rectifier is connected with the direct current end of the energy storage converter. The method comprises: controlling the energy storage converter by using a VSG control method, so that the energy storage converter provides virtual rotor inertia and maintains the stability of the power grid frequency. The above method considers the characteristics of the flywheel energy storage module as a rotating system with fast response speed. The flywheel energy storage module compensates for the slow response speed of the target energy storage module VSG of the non-rotating system, so that the energy storage converter provides virtual rotor inertia adaptive to the change of the power grid frequency, and the stability of the power grid frequency is improved.

Description

Technical Field

[0001] This invention relates to the field of energy storage system technology, and in particular to a VSG control method and related device for an energy storage system. Background Technology

[0002] Synchronous generators provide a large amount of mechanical inertia to the power grid, enabling them to naturally synchronize with the grid and participate in the regulation of grid voltage and frequency. When a power system fault occurs, the mechanical inertia of the synchronous generator can provide sufficient spinning reserve capacity to compensate for the power loss in the system. As the proportion of photovoltaic energy storage systems connected to the grid continues to increase, the proportion of synchronous generators in the power system is decreasing accordingly.

[0003] To compensate for the insufficient voltage and frequency regulation capabilities brought about by the grid integration of photovoltaic (PV) and energy storage, existing technologies typically employ Virtual Synchronous Generators (VSGs) to embed the rotor motion equations and reactive power droop control algorithms of synchronous generators into the inverter control system. When the grid experiences faults or disturbances, the distributed generation of the inverter control system is adjusted to achieve operating characteristics similar to a synchronous generator. Although PV-energy storage VSGs can add virtual inertia to the grid, their response speed is slow, resulting in poor improvement in power system stability. Summary of the Invention

[0004] This invention provides a VSG control method and related apparatus for an energy storage system to address the problem that existing photovoltaic-storage VSGs are not effective in improving power system stability.

[0005] In a first aspect, embodiments of the present invention provide a VSG control method for an energy storage system, the energy storage system comprising a target energy storage module, a flywheel energy storage module, an energy storage converter, and a rectifier; the output terminal of the target energy storage module is connected to the DC terminal of the energy storage converter, the output terminal of the energy storage converter is connected to the grid bus, the output terminal of the flywheel energy storage module is connected to the AC terminal of the rectifier, and the DC terminal of the rectifier is connected to the DC terminal of the energy storage converter;

[0006] The method includes:

[0007] The energy storage converter is controlled using the VSG control method to enable it to provide virtual rotor inertia and maintain the stability of the grid frequency.

[0008] Secondly, embodiments of the present invention provide a VSG control device for an energy storage system, the energy storage system including a target energy storage module, a flywheel energy storage module, an energy storage converter, and a rectifier; the output terminal of the target energy storage module is connected to the DC terminal of the energy storage converter, the output terminal of the energy storage converter is connected to the grid bus, the output terminal of the flywheel energy storage module is connected to the AC terminal of the rectifier, and the DC terminal of the rectifier is connected to the DC terminal of the energy storage converter;

[0009] The device includes:

[0010] The VSG control module is used to control the energy storage converter using the VSG control method, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency.

[0011] Thirdly, embodiments of the present invention provide a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the VSG control method of the energy storage system as described in any possible implementation of the first aspect above.

[0012] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the VSG control method for the energy storage system as described in any possible implementation of the first aspect above.

[0013] Fifthly, embodiments of the present invention provide an energy storage system, which includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and a terminal as described in the third aspect above;

[0014] The output terminal of the target energy storage module is connected to the DC terminal of the energy storage converter, the output terminal of the energy storage converter is connected to the grid bus, the output terminal of the flywheel energy storage module is connected to the AC terminal of the rectifier, and the DC terminal of the rectifier is connected to the DC terminal of the energy storage converter.

[0015] This invention provides a VSG control method and related apparatus for an energy storage system. The energy storage system includes a target energy storage module, a flywheel energy storage module, an energy storage converter, and a rectifier. The VSG control method controls the energy storage converter to provide virtual rotor inertia, thereby maintaining the stability of the power grid frequency. This method takes into account the fast response speed of the flywheel energy storage module as a rotating system. By having the flywheel energy storage module and the target energy storage module jointly provide virtual inertia to the power grid, the stability of the power grid frequency is improved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is an application scenario diagram of the VSG control method for an energy storage system provided in an embodiment of the present invention;

[0018] Figure 2 This is a flowchart illustrating the implementation of the VSG control method for an energy storage system provided in this embodiment of the invention.

[0019] Figure 3 This is a VSG control flowchart provided in an embodiment of the present invention;

[0020] Figure 4 This is a flowchart of SPWM signal generation provided in an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of the VSG control device of the energy storage system provided in the embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the terminal provided in an embodiment of the present invention. Detailed Implementation

[0023] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0025] Figure 1 This diagram illustrates an application scenario of the VSG control method for an energy storage system provided in an embodiment of the present invention. Figure 1As shown, the energy storage system includes target energy storage modules BAT, flywheel energy storage modules M (M1, M2, ..., MN), energy storage converters PCS (PCS1, PCS2, ..., PCSn), and rectifiers AC / DC. Each target energy storage module BAT is connected to the grid bus through its corresponding energy storage converter PCS. Each flywheel energy storage module is connected to the AC terminal of its corresponding rectifier. The DC terminal of each rectifier is connected to the input terminal of its corresponding energy storage converter. The output terminal of each energy storage converter is connected to the grid bus. The output terminal of each flywheel energy storage module is also used to connect to the grid bus.

[0026] Specifically, the target energy storage module can be any energy storage module other than a flywheel energy storage module, and may include photovoltaic energy storage modules, wind power energy storage modules, or energy storage batteries. When the target energy storage module is a photovoltaic energy storage module, it includes a photovoltaic plate, a DC-DC converter module, and a battery module. The photovoltaic plate is connected to one end of the DC-DC converter module, and the other end of the DC-DC converter module is connected to both the output terminal of the target energy storage module and the battery module. The method provided in this application will be described in detail below using a photovoltaic energy storage module as an example.

[0027] See Figure 2 The flowchart illustrating the implementation of the VSG control method for an energy storage system provided in this embodiment of the invention is shown below:

[0028] S101: The energy storage converter is controlled using the VSG control method so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency.

[0029] In this embodiment, the execution entity is the control host of the energy storage system. The control host is communicatively connected to the controller of the target energy storage module, the controller of the rectifier, and the controller of the energy storage converter. It is used to issue power control commands to the controller of the rectifier and the controller of the target energy storage module, and to issue VSG control commands to the controller of the energy storage converter. The flywheel energy storage module and the target energy storage module each provide power to the energy storage converter so that the energy storage converter outputs the corresponding virtual rotor inertia to maintain the stability of the grid frequency.

[0030] In this embodiment, virtual synchronous generator (VSG) technology simulates the electromechanical transient characteristics of synchronous generator sets, enabling power supplies or loads using converters to possess the inertia, damping, frequency, and voltage regulation characteristics of synchronous generator sets. Since common energy storage systems, such as photovoltaic (PV) energy storage systems, are typically non-rotating systems, their corresponding virtual synchronous generators respond slowly to changes in grid frequency. Therefore, they cannot promptly regulate the grid frequency when grid fluctuations are significant. In this embodiment, during the primary frequency regulation control stage, a flywheel energy storage module is connected to the grid. This avoids further grid fluctuations and compensates for the slow response speed of the non-rotating PV energy storage VSG through the virtual inertia provided by the flywheel energy storage. Thus, when grid frequency fluctuations are significant, both flywheel and PV energy storage jointly provide virtual inertia to the grid, enabling the grid frequency to stabilize quickly.

[0031] 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:

[0032] The virtual rotor inertia is adaptively determined based on the power grid frequency;

[0033] The virtual rotor inertia is divided into a fixed first virtual rotor inertia and a second virtual rotor inertia that adaptively varies with the power grid frequency;

[0034] The given output power of the target energy storage module is controlled based on the first virtual rotor inertia.

[0035] The given output power of the rectifier is controlled based on the second virtual rotor inertia.

[0036] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0037] In one possible implementation, the specific process for determining the virtual rotor inertia includes:

[0038] Based on formula

[0039]

[0040] Calculate the virtual rotor inertia;

[0041] In equation (1), J represents the virtual rotor inertia, J0 represents the steady-state value of the virtual rotor inertia; ω represents the virtual rotor angular velocity of the energy storage converter. g Represents the angular velocity of the power grid, and ω g =2πf g , where f g The frequency of the power grid is represented by k, which is a constant, and C represents the threshold value of the rate of change of the virtual rotor angular velocity.

[0042] Wherein, J0 represents the steady-state value of the virtual rotor inertia, which can be determined based on the natural vibration angular velocity of the synchronous generator.

[0043] Specifically, the magnitude of the virtual rotor inertia is determined by the difference between the virtual angular velocity of the VSG and the grid angular velocity, as well as the magnitude of the virtual angular rate. When the virtual angular velocity of the VSG is greater than the grid angular velocity and the virtual angular rate of the VSG is greater than zero, the virtual rotor inertia increases. When the virtual angular velocity of the VSG is greater than the grid angular velocity and the virtual angular rate of the VSG is less than zero, the virtual rotor inertia decreases. Conversely, when the virtual angular velocity of the VSG is less than the grid angular velocity and the virtual angular rate of the VSG is less than zero, the virtual rotor inertia increases. When the virtual angular velocity of the VSG is less than the grid angular velocity and the virtual angular rate of the VSG is greater than zero, the virtual rotor inertia decreases. Based on the above principles, this application adaptively determines the required virtual rotor inertia output by the energy storage converter VSG based on grid frequency, thereby improving the frequency response speed of the energy storage system.

[0044] In this embodiment, the energy storage converter performs VSG control according to a fixed control cycle. The virtual rotor inertia J of the energy storage converter VSG in the current control cycle in the above formula (1) is calculated by the current grid frequency and the virtual rotor angular velocity of the VSG in the previous control cycle. After determining the virtual rotor inertia J of the current control cycle, the virtual rotor inertia is divided into two parts (first virtual rotor inertia and second virtual rotor inertia). One part is provided by the output power of the flywheel energy storage module, and the other part is provided by the output power of the target energy storage module. Therefore, it is necessary to determine the given output power of the target energy storage module based on the first virtual rotor inertia and the given output power of the flywheel energy storage module based on the second virtual rotor inertia.

[0045] 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 virtual rotor inertia to perform VSG control on the energy storage converter includes:

[0046] 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 ;

[0047] S202: Input the active power P of the energy storage converter into the active-frequency regulation loop, and output the phase of VSG. The virtual rotor inertia is a parameter value in the active-frequency regulation loop;

[0048] 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.

[0049] Specifically, the implementation process of S201 includes:

[0050] Obtain the actual input voltage U of the energy storage converter o ;

[0051] Input voltage rating U ref Subtract the actual input voltage U o The input voltage error is obtained;

[0052] 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;

[0053] 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. q Multiply them to obtain the second control variable;

[0054] 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 ;

[0055] Specifically, such as Figure 3 As shown, the specific implementation process of S202 includes:

[0056] Given active power P ref Subtract the input active power P of the energy storage converter to obtain the active power difference;

[0057] 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.

[0058] 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.

[0059] In one possible implementation, the specific implementation process of S203 includes:

[0060] Based on formula

[0061]

[0062] Calculate the three-phase setpoint voltage of the energy storage converter VSG;

[0063] In equation (2), 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.

[0064] 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 4 in,i ref Indicates the rated grid-connected current, i a i b and i c These represent the three-phase output currents; i e This indicates the output current deviation; PR stands for proportional resonant regulator, L represents inductance, R represents local resistance, and u... m This indicates the voltage amplitude of the modulated signal.

[0065] In this embodiment, after obtaining the sinusoidal pulse width modulation signal, the sinusoidal pulse width modulation signal is used to control each switch of the energy storage converter so that the energy storage converter outputs the corresponding virtual rotor inertia.

[0066] As can be seen from the above process, the magnitude of the virtual rotor angular velocity depends on the input power of the energy storage converter. The input power of the energy storage converter is determined by the sum of the output power of the target energy storage module and the output power of the corresponding rectifier of the flywheel energy storage module. Therefore, the virtual rotor angular velocity of the VSG can be adjusted by setting the given output power of the rectifier and the given output power of the target energy storage module, thereby adjusting the virtual rotor inertia output by the VSG.

[0067] As can be seen from the above embodiments, when the power grid system is relatively stable, this embodiment uses the original photovoltaic energy storage module corresponding to the VSG to stabilize the power grid frequency. When the power grid frequency fluctuates greatly, based on the advantages of the fast response speed of the adaptive virtual rotor inertia method and the inherent fast response speed of the flywheel energy storage system as a rotating system, flywheel energy storage is used to provide virtual rotor inertia to fine-tune the power grid frequency on the basis of photovoltaic energy storage VSG. This not only makes full use of the fast response speed advantage of the flywheel energy storage VSG as a rotating system, but also eliminates the need to configure a large-capacity flywheel energy storage module.

[0068] 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:

[0069] The virtual rotor inertia is adaptively determined based on the power grid frequency;

[0070] The virtual rotor inertia is divided into a first virtual rotor inertia that adapts to the power grid frequency and a fixed second virtual rotor inertia;

[0071] The given output power of the target energy storage module is controlled based on the first virtual rotor inertia.

[0072] The given output power of the rectifier is controlled based on the second virtual rotor inertia.

[0073] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0074] This embodiment can preferentially allocate a fixed output power to the rectifier corresponding to the flywheel energy storage module, and enable the target energy storage module to provide an output power that adapts to changes in grid frequency, thereby improving the response speed of the energy storage converter VSG and further improving grid frequency stability.

[0075] In one possible implementation, the specific implementation process of S101 includes:

[0076] Virtual rotor inertia is obtained adaptively based on power grid frequency;

[0077] If the virtual rotor inertia is less than or equal to the first maximum rotor inertia, then the virtual rotor inertia is used to control the given output power of the target energy storage module, and the given output power of the rectifier module is controlled to be zero.

[0078] If the virtual rotor inertia is greater than the first maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the target energy storage module, and the second virtual rotor inertia is used to control the given output power of the rectifier module; the second virtual rotor inertia is the difference between the virtual rotor inertia and the first maximum rotor inertia.

[0079] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0080] Specifically, in this embodiment, the target energy storage module can be used first to provide power to the energy storage converter VSG. Only when the output power of the target energy storage module is insufficient to support the virtual rotor inertia requirement of the energy storage converter VSG will the flywheel energy storage module be activated to provide power to the energy storage converter. The magnitude of the virtual rotor angular velocity is positively correlated with the input power of the energy storage converter. Therefore, when only the target energy storage module is used to supply power to the energy storage converter, the first maximum rotor inertia value is the virtual rotor inertia output by the energy storage converter when the target energy storage module has its maximum overload capacity.

[0081] In this embodiment, if the control host detects that the virtual rotor inertia is equal to the maximum value of the first rotor inertia for a continuous first preset time period, or if the number of sampling moments in which the virtual rotor inertia is equal to the maximum value of the first rotor inertia for a continuous second preset time period accounts for a preset percentage of the total number of sampling moments in the second preset time period, then it determines that the output power of the target energy storage module cannot enable the energy storage converter to output sufficient virtual inertia to support the grid frequency. Then, it controls the rectifier to output power to the energy storage converter to ensure that the energy storage converter VSG outputs sufficient virtual rotor inertia.

[0082] The preset percentage can be 60% to 80%.

[0083] In one possible implementation, the specific implementation process of S101 includes:

[0084] Virtual rotor inertia is obtained adaptively based on power grid frequency;

[0085] If the virtual rotor inertia is less than or equal to the maximum value of the second rotor inertia, then the virtual rotor inertia is used to control the given output power of the rectifier module and control the given output power of the target energy storage module to be zero.

[0086] If the virtual rotor inertia is greater than the second maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the rectifier module, and the second virtual rotor inertia is used to control the given output power of the target energy storage module; the second virtual rotor inertia is the difference between the virtual rotor inertia requirement value and the first maximum rotor inertia value.

[0087] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0088] Specifically, in this embodiment, the flywheel energy storage module can be used first to provide power to the energy storage converter VSG. When the output power of the flywheel energy storage module is insufficient to support the virtual rotor inertia requirement of the energy storage converter VSG, the target energy storage module is then activated to provide power to the energy storage converter. The magnitude of the virtual rotor angular velocity is positively correlated with the input power of the energy storage converter. Therefore, when only the flywheel energy storage module is used to supply power to the energy storage converter, the maximum value of the second rotor inertia is the virtual rotor inertia output by the energy storage converter when the flywheel energy storage module has its maximum overload capacity.

[0089] In this embodiment, if the control host detects that the virtual rotor inertia is equal to the maximum value of the second rotor inertia for a continuous first preset duration, or if the number of sampling moments in which the virtual rotor inertia is equal to the maximum value of the second rotor inertia for a continuous first preset duration accounts for a preset percentage of the total number of sampling moments in the entire second preset duration, then it determines that the output power of the flywheel energy storage module is insufficient to enable the energy storage converter to output sufficient virtual inertia to support the grid frequency. Then, it controls the target energy storage module to output power to the energy storage converter to ensure that the energy storage converter VSG outputs sufficient virtual rotor inertia.

[0090] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0091] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0092] Figure 5 A schematic diagram of the VSG control device of the energy storage system provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0093] like Figure 5 As shown, the VSG control device 100 of the energy storage system includes:

[0094] VSG control module 110 is used to control the energy storage converter using the VSG control method, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency.

[0095] 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:

[0096] A virtual rotor inertia acquisition unit is used to adaptively determine the virtual rotor inertia based on the power grid frequency.

[0097] The first inertia division unit is used to divide the virtual rotor inertia into a fixed first virtual rotor inertia and a second virtual rotor inertia that adapts to the power grid frequency.

[0098] The target energy storage module control unit is used to control the given output power of the target energy storage module based on the first virtual rotor inertia;

[0099] A rectifier control unit is configured to control the given output power of the rectifier based on the second virtual rotor inertia.

[0100] The VSG control unit is used to perform VSG control on the energy storage converter using the virtual rotor inertia.

[0101] In one possible implementation, the virtual rotor inertia acquisition unit includes:

[0102] Based on formula Calculate the virtual rotor inertia;

[0103] Where J represents the virtual rotor inertia, J0 represents the steady-state value of the virtual rotor inertia; ω represents the virtual rotor angular velocity of the energy storage converter, ω g Represents the angular velocity of the power grid, and ω g =2πf g , where f g The frequency of the power grid is represented by k, which is a constant, and C represents the threshold value of the rate of change of the virtual rotor angular velocity.

[0104] In one possible implementation, the VSG control module 110 includes:

[0105] The virtual rotor inertia is adaptively determined based on the power grid frequency;

[0106] The virtual rotor inertia is divided into a first virtual rotor inertia that adapts to the power grid frequency and a fixed second virtual rotor inertia;

[0107] The given output power of the target energy storage module is controlled based on the first virtual rotor inertia.

[0108] The given output power of the rectifier is controlled based on the second virtual rotor inertia.

[0109] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0110] In one possible implementation, the VSG control module 110 includes:

[0111] Virtual rotor inertia is obtained adaptively based on power grid frequency;

[0112] If the virtual rotor inertia is less than or equal to the first maximum rotor inertia, then the virtual rotor inertia is used to control the given output power of the target energy storage module, and the given output power of the rectifier module is controlled to be zero.

[0113] If the virtual rotor inertia is greater than the first maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the target energy storage module, and the second virtual rotor inertia is used to control the given output power of the rectifier module; the second virtual rotor inertia is the difference between the virtual rotor inertia and the first maximum rotor inertia.

[0114] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0115] In one possible implementation, the VSG control module 110 includes:

[0116] Virtual rotor inertia is obtained adaptively based on power grid frequency;

[0117] If the virtual rotor inertia is less than or equal to the maximum value of the second rotor inertia, then the virtual rotor inertia is used to control the given output power of the rectifier module and control the given output power of the target energy storage module to be zero.

[0118] If the virtual rotor inertia is greater than the second maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the rectifier module, and the second virtual rotor inertia is used to control the given output power of the target energy storage module; the second virtual rotor inertia is the difference between the virtual rotor inertia requirement value and the first maximum rotor inertia value.

[0119] The virtual rotor inertia is used to perform VSG control on the energy storage converter.

[0120] 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, which has a fast response speed. The flywheel energy storage module compensates for the disadvantage of the slow response speed of the target energy storage module in a non-rotating system, thereby jointly providing power to the energy storage converter, so that the energy storage converter can provide a virtual rotor inertia that adapts to changes in grid frequency, thereby improving the stability of grid frequency.

[0121] 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 VSG control method embodiments of the various energy storage systems described above, for example... Figure 2Step 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.

[0122] 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.

[0123] The terminal 6 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The terminal 6 may include, but is not limited to, a processor 60 and a memory 61. Those skilled in the art will understand that... Figure 6 This is merely an example of terminal 6 and does not constitute a limitation on terminal 6. It may include more or fewer components than shown, or combine certain components, or different components. For example, the terminal may also include input / output devices, network access devices, buses, etc.

[0124] The processor 60 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0125] The memory 61 can be an internal storage unit of the terminal 6, such as a hard disk or memory of the terminal 6. The memory 61 can also be an external storage device of the terminal 6, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the terminal 6. Furthermore, the memory 61 can include both internal storage units and external storage devices 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.

[0126] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments 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. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0127] This invention provides an energy storage system, which includes a target energy storage module, a flywheel energy storage module, an energy storage converter, a rectifier, and a terminal as described above;

[0128] The output terminal of the target energy storage module is connected to the DC terminal of the energy storage converter, the output terminal of the energy storage converter is connected to the grid bus, the output terminal of the flywheel energy storage module is connected to the AC terminal of the rectifier, and the DC terminal of the rectifier is connected to the DC terminal of the energy storage converter.

[0129] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0130] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented 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 implementations should not be considered beyond the scope of this invention.

[0131] In the embodiments provided by this invention, 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 merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0132] 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.

[0133] 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.

[0134] 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 methods of 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 VSG control method embodiments of the various energy storage systems described above. 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.

[0135] 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 VSG control method for an energy storage system, characterized in that, The energy storage system includes multiple target energy storage modules, multiple flywheel energy storage modules, multiple energy storage converters, and corresponding rectifiers; The output terminals of each energy storage converter are connected to the grid bus. The input terminals of each energy storage converter are connected to the DC terminal of their respective rectifiers and the output terminal of the target energy storage module. The AC terminal of each rectifier is connected to the output terminal of its respective flywheel energy storage module. The output terminals of each flywheel energy storage module are also used to connect to the grid bus. The method includes: The energy storage converter is controlled using the VSG control method so that it provides virtual rotor inertia to maintain the stability of the grid frequency. The method of using VSG control to control the energy storage converter, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency, includes: The virtual rotor inertia is adaptively determined based on the power grid frequency; The virtual rotor inertia is divided into a fixed first virtual rotor inertia and a second virtual rotor inertia that adaptively varies with the power grid frequency; The given output power of the target energy storage module is controlled based on the first virtual rotor inertia. The given output power of the rectifier is controlled based on the second virtual rotor inertia. Alternatively, the method of using VSG control to control the energy storage converter to enable the energy storage converter to provide virtual rotor inertia and maintain the stability of the grid frequency includes: The virtual rotor inertia is adaptively determined based on the power grid frequency; The virtual rotor inertia is divided into a first virtual rotor inertia that adapts to the power grid frequency and a fixed second virtual rotor inertia; The given output power of the target energy storage module is controlled based on the first virtual rotor inertia. The given output power of the rectifier is controlled based on the second virtual rotor inertia. Alternatively, the method of using VSG control to control the energy storage converter, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency, further includes: Virtual rotor inertia is obtained adaptively based on power grid frequency; If the virtual rotor inertia is less than or equal to the first maximum rotor inertia, then the virtual rotor inertia is used to control the given output power of the target energy storage module, and the given output power of the rectifier is controlled to be zero. If the virtual rotor inertia is greater than the first maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the target energy storage module, and the second virtual rotor inertia is used to control the given output power of the rectifier; the second virtual rotor inertia is the difference between the virtual rotor inertia and the first maximum rotor inertia.

2. The VSG control method for an energy storage system according to claim 1, characterized in that, The step of adaptively determining the virtual rotor inertia based on the power grid frequency includes: Based on formula Calculate the virtual rotor inertia; in, J This represents the virtual rotor inertia. J 0 represents the steady-state value of the virtual rotor inertia; This represents the virtual rotor angular velocity of the energy storage converter. 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 VSG control method for an energy storage system according to claim 1, characterized in that, The method of using VSG control to control the energy storage converter, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency, further includes: If the virtual rotor inertia is less than or equal to the maximum value of the second rotor inertia, then the virtual rotor inertia is used to control the given output power of the rectifier and control the given output power of the target energy storage module to be zero. If the virtual rotor inertia is greater than the second maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the rectifier, and the second virtual rotor inertia is used to control the given output power of the target energy storage module; the second virtual rotor inertia is the difference between the virtual rotor inertia and the first maximum rotor inertia.

4. A VSG control device for an energy storage system, characterized in that, include: The energy storage system includes multiple target energy storage modules, multiple flywheel energy storage modules, and multiple energy storage converters; The output terminals of each energy storage converter are connected to the grid bus. The input terminals of each energy storage converter are connected to the DC terminal of their respective rectifiers and the output terminal of the target energy storage module. The AC terminal of each rectifier is connected to the output terminal of its respective flywheel energy storage module. The output terminals of each flywheel energy storage module are also used to connect to the grid bus. The device includes: The VSG control module is used to control the energy storage converter using the VSG control method, so that the energy storage converter provides virtual rotor inertia to maintain the stability of the grid frequency. The VSG control module includes: The virtual rotor inertia is adaptively determined based on the power grid frequency; The virtual rotor inertia is divided into a fixed first virtual rotor inertia and a second virtual rotor inertia that adaptively varies with the power grid frequency; The given output power of the target energy storage module is controlled based on the first virtual rotor inertia. The given output power of the rectifier is controlled based on the second virtual rotor inertia. Alternatively, the VSG control module includes: adaptively determining the virtual rotor inertia based on the power grid frequency; The virtual rotor inertia is divided into a first virtual rotor inertia that adapts to the power grid frequency and a fixed second virtual rotor inertia; The given output power of the target energy storage module is controlled based on the first virtual rotor inertia. The given output power of the rectifier is controlled based on the second virtual rotor inertia. Alternatively, the VSG control module includes: Virtual rotor inertia is obtained adaptively based on power grid frequency; If the virtual rotor inertia is less than or equal to the first maximum rotor inertia, then the virtual rotor inertia is used to control the given output power of the target energy storage module, and the given output power of the rectifier is controlled to be zero. If the virtual rotor inertia is greater than the first maximum rotor inertia, then the first maximum rotor inertia is used to control the given output power of the target energy storage module, and the second virtual rotor inertia is used to control the given output power of the rectifier; the second virtual rotor inertia is the difference between the virtual rotor inertia and the first maximum rotor inertia.

5. A terminal, characterized in that, It includes a processor and a memory, the memory being used to store computer programs, and the processor being used to call and run the computer programs stored in the memory to execute the VSG control method of the 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 VSG control method for the 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, and the terminal as described in claim 5; The output terminal of the target energy storage module is connected to the DC terminal of the energy storage converter, the output terminal of the energy storage converter is connected to the grid bus, the output terminal of the flywheel energy storage module is connected to the AC terminal of the rectifier, and the DC terminal of the rectifier is connected to the DC terminal of the energy storage converter.

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