Control method of network-building type energy storage system based on virtual inertia and virtual damping

Abstract

The invention provides a virtual inertia and virtual damping-based control method for a network-building type energy storage system, and belongs to the technical field of network-building type energy storage system control. The method comprises the following steps: firstly, based on target control parameters obtained by applying small disturbance quantity and energy consumed by direct-current energy storage equipment, transforming an expression after derivation of virtual rotor storage energy; then respectively calculating a variable virtual inertia and a variable virtual damping coefficient by means of a synchronous machine swing equation or based on a damping ratio of an active power transfer function and a target control parameter, and respectively calculating a target virtual inertia and a target virtual damping coefficient based on the target control parameter and based on the variable virtual inertia or the variable virtual damping coefficient; and finally, based on the calculated target virtual inertia and the target virtual damping coefficient, controlling the network-building type energy storage system. According to the scheme, the energy storage demand, the active power oscillation and the control frequency oscillation can be reduced, and the method has relatively high usability and practicability.

Description

Technical Field

[0001] The present application relates to the technical field of grid-type energy storage system control, and specifically to a control method for a grid-type energy storage system based on virtual inertia and virtual damping. Background Art

[0002] In the prior art, the control methods for grid-type energy storage systems mainly include: adaptive inertia control (adaptive J control) and control based on alternating inertia and damping (alternating J and DP control). In these two methods, the active control process has a greater demand for energy storage in the adaptive control process, and the adaptive inertia control is also prone to cause active power and control frequency oscillation.

[0003] Therefore, how to reduce the demand for energy storage, active power oscillation and control frequency oscillation have become issues to be solved. Summary of the invention

[0004] The purpose of this application is to provide a control method for a grid-type energy storage system based on virtual inertia and virtual damping, which can solve the problems in the prior art of how to reduce the demand for energy storage, active power oscillation and frequency oscillation.

[0005] In a first aspect, an embodiment of the present application provides a control method for a grid-type energy storage system based on virtual inertia and virtual damping, the method comprising:

[0006] During the operation of the grid-type energy storage system, a small disturbance is applied to the steady-state value of the control parameter to obtain the target control parameter;

[0007] Based on the target control parameter and the energy consumed or supplied by the DC energy storage device, the derived expression of the virtual rotor storage energy is transformed to obtain a transformed expression of the virtual rotor storage energy;

[0008] The variable virtual inertia is calculated based on the transformed expression of virtual rotor storage energy and the synchronous machine swing equation, and the variable virtual damping coefficient is calculated based on the damping ratio of the active power transfer function and the target control parameter;

[0009] Based on the target control parameter and the variable virtual inertia, the target virtual inertia is calculated; based on the target control parameter and the variable virtual damping coefficient, the target virtual damping coefficient is calculated;

[0010] Based on the target virtual inertia and the target virtual damping coefficient, the grid-type energy storage system is controlled.

[0011] In a possible implementation of the first aspect, the control parameters include: a control frequency, a reference frequency, energy consumed or supplied by a DC energy storage device, a virtual inertia, and a virtual damping coefficient. The expression of the target control parameter is: Among them, ω represents the control frequency, ω n represents the steady-state value of the control frequency, represents the small disturbance of the control frequency, ω0 represents the reference frequency, ω 0n represents the steady-state value of the reference frequency, represents the small disturbance of the reference frequency, E represents the energy consumed or supplied by the DC energy storage device, E0 represents the steady-state value of the energy consumed or supplied by the DC energy storage device, It represents the small disturbance of energy consumed or supplied by the DC energy storage device, J represents the virtual inertia, J0 represents the steady-state value of the virtual inertia, Indicates variable virtual inertia, D P represents the virtual damping coefficient, D p0 represents the steady-state value of the virtual damping coefficient, represents the variable virtual damping coefficient; the expression of the energy consumed or supplied by the DC energy storage device is Where, E(t) represents the energy consumed or supplied by the DC energy storage device, t represents time, Pm represents the reference active power, and Pe represents the actual output active power. represents a small disturbance of the reference active power, represents the small disturbance of active power; the expression of virtual rotor storage energy is The derivative expression of virtual rotor storage energy is: Based on the target control parameters and the energy consumed or supplied by the DC energy storage device, the expression after the derivation of the virtual rotor storage energy is transformed to obtain the transformed expression of the virtual rotor storage energy, including:

[0012] Substitute E in the expression of the target control parameter into the expression of the energy consumed or supplied by the DC energy storage device, and derive the energy consumed or supplied by the DC energy storage device to obtain the following expression:

[0013]

[0014] Among them, in expression (1)

[0015] Substituting J and ω in the expression of the target control parameter into the expression after the derivative of the virtual rotor storage energy, the following expression is obtained:

[0016]

[0017] Substituting expression (1) into expression (2), we obtain the following transformed expression for the virtual rotor stored energy:

[0018]

[0019] In a possible implementation of the first aspect, the synchronous machine swing equation is: The variable virtual inertia is calculated based on the transformed expression of virtual rotor stored energy and the synchronous machine swing equation, including:

[0020] Substituting D in expression (3) and the expression of the target control parameter P Substituting ω0 into the synchronous machine swing equation, we get the following expression:

[0021]

[0022] Ignoring the product of the steady-state value of the control parameter and the small disturbance in expression (4), simplifying expression (4) yields the following expression:

[0023]

[0024] The variable virtual inertia is calculated according to expression (5), and the expression of the variable virtual inertia is as follows:

[0025]

[0026] Where δ represents the load angle, represents a small perturbation of the load angle, The integral is

[0027] In a possible implementation manner of the first aspect, the expression of the damping ratio of the active power transfer function is: ω N represents the natural oscillation frequency, K is a constant, Von represents the rated output voltage of the grid-type energy storage system, Vgn represents the grid voltage, and Xs represents the grid impedance. The variable virtual damping coefficient is calculated based on the damping ratio of the active power transfer function and the target control parameter, including:

[0028] Transforming the expression of the damping ratio of the active power transfer function, we get the following expression:

[0029] D P =2Jζω N (7);

[0030] Substituting Dp and J in the expression of the target control parameter into expression (7) and ignoring the steady-state value of the control parameter, the variable virtual damping coefficient is calculated. The expression of the variable virtual damping coefficient is as follows:

[0031]

[0032] Among them, ω N0is the intermediate variable, A small perturbation that represents the natural oscillation frequency.

[0033] In a possible implementation manner of the first aspect, calculating the target virtual inertia based on the target control parameter and the variable virtual inertia includes:

[0034] Based on J in the expression of the target control parameter and the expression of the variable virtual inertia, the target virtual inertia is calculated. The expression of the target virtual inertia is as follows:

[0035]

[0036] In a possible implementation manner of the first aspect, calculating the target virtual damping coefficient based on the target control parameter and the variable virtual damping coefficient includes:

[0037] Based on Dp in the expression of the target control parameter and the expression of the variable virtual damping coefficient, the target virtual damping coefficient is calculated and the expression of the target virtual damping coefficient is as follows:

[0038]

[0039] Among them, D P0 Determined by the power grid.

[0040] In a possible implementation manner of the first aspect, the method further includes:

[0041] Substitute Dp in expression (10) into the expression of damping frequency to calculate J in the expression of damping frequency; where the expression of damping frequency is:

[0042] Let J in the expression of damping frequency be J0 in expression (9);

[0043] J in expression (9) is calculated based on J0 in expression (9).

[0044] In a possible implementation manner of the first aspect, the method further includes:

[0045] Based on the energy consumed or supplied by the DC energy storage device, the energy absorbed or consumed by the DC energy storage device in the critical damping grid energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system are calculated; based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system, the damping ratio is determined.

[0046] In a possible implementation manner of the first aspect, the energy consumed or supplied by the DC energy storage device is expressed as: Among them, ωd represents the damping frequency, ζ represents the damping ratio, ζ=DP2ω0JK, φ is the intermediate variable, Based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system, the damping ratio is determined, including:

[0047] Substituting ζ=1 into the expression of energy consumed or supplied by the DC energy storage device, the following expression of energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system is obtained:

[0048]

[0049] Among them, when t→∞, the expression of the energy absorbed or consumed by the DC energy storage device in the critical damping grid energy storage system is as follows:

[0050]

[0051] Set t = t r Substituting the expression of energy consumed or supplied by the DC energy storage device, the following expression of energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system is obtained:

[0052]

[0053] Among them, when t r =(π-φ) / ω d When , the expression of energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system is as follows:

[0054]

[0055] Based on the absorbed energy diagram determined by expression (12) and the absorbed energy diagram determined by expression (14), the damping ratio is determined.

[0056] In a second aspect, an embodiment of the present application provides a control device for a grid-type energy storage system based on virtual inertia and virtual damping, the device comprising:

[0057] An applying unit, used for applying a small disturbance amount to the steady-state value of the control parameter during the operation of the grid-type energy storage system to obtain a target control parameter;

[0058] A transformation unit, used to transform the derivative expression of the virtual rotor storage energy based on the target control parameter and the energy consumed or supplied by the DC energy storage device, to obtain a transformed expression of the virtual rotor storage energy;

[0059] A first calculation unit is used to calculate the variable virtual inertia based on the transformed expression of the virtual rotor storage energy and the synchronous machine swing equation, and calculate the variable virtual damping coefficient based on the damping ratio of the active power transfer function and the target control parameter;

[0060] A second calculation unit is used to calculate a target virtual inertia based on the target control parameter and the variable virtual inertia, and to calculate a target virtual damping coefficient based on the target control parameter and the variable virtual damping coefficient;

[0061] The control unit is used to control the grid-type energy storage system based on the target virtual inertia and the target virtual damping coefficient.

[0062] In a third aspect, an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the control method of a grid-type energy storage system based on virtual inertia and virtual damping described in any one of the first aspects above is implemented.

[0063] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements any control method of a grid-type energy storage system based on virtual inertia and virtual damping in the above-mentioned first aspect.

[0064] In a fifth aspect, an embodiment of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes any one of the control methods of a grid-type energy storage system based on virtual inertia and virtual damping in the first aspect.

[0065] The present application first transforms the expression after the derivative of the virtual rotor stored energy based on the target control parameters obtained by applying a small disturbance and the energy consumed by the DC energy storage device, and then calculates the variable virtual inertia and the variable virtual damping coefficient respectively with the help of the synchronous machine swing equation or the damping ratio and the target control parameters based on the active power transfer function, and then calculates the target virtual inertia and the target virtual damping coefficient based on the target control parameters and the variable virtual inertia or the variable virtual damping coefficient, and finally controls the grid-type energy storage system based on the calculated target virtual inertia and target virtual damping coefficient.

[0066] The solution of the present application can reduce the demand for energy storage, active power oscillation and control frequency oscillation, and has strong ease of use and practicality.

[0067] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0069] Figure 1 It is a schematic diagram of the steps of a control method of a grid-type energy storage system based on virtual inertia and virtual damping provided in an embodiment of the present application;

[0070] Figure 2 is a calculation block diagram of the target virtual inertia and the target virtual damping coefficient provided in an embodiment of the present application;

[0071] Figure 3 is a control block diagram of a grid-type energy storage system provided in an embodiment of the present application;

[0072] Figure 4 is a schematic diagram of the topological structure of a meshed converter provided in an embodiment of the present application;

[0073] Figure 5 It is a block diagram of an active power control small signal provided in an embodiment of the present application;

[0074] Figure 6 It is a schematic diagram of the effect of the change of the virtual damping coefficient on the transient response of the active power provided in the embodiment of the present application;

[0075] Figure 7 It is a schematic diagram of the influence of the change of the virtual damping coefficient on the control frequency transient response of the grid-type energy storage system provided in the embodiment of the present application;

[0076] Figure 8 It is a schematic diagram of the influence of the virtual inertia change on the active power transient response provided by the embodiment of the present application;

[0077] Fig. 9 It is a schematic diagram of the influence of the change of virtual inertia on the control frequency transient response of the grid-type energy storage system provided in the embodiment of the present application;

[0078] Fig.10 is a schematic diagram of energy absorption by a critical damping system provided in an embodiment of the present application;

[0079] Fig.11 is a schematic diagram of energy absorption by an underdamped system provided in an embodiment of the present application;

[0080] Fig.12 It is a structural schematic diagram of a control device of a grid-type energy storage system based on virtual inertia and virtual damping provided in an embodiment of the present application;

[0081] Fig.13 It is a schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0082] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0083] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0084] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0085] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0086] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0087] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0088] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0089] In the prior art, the control methods for grid-type energy storage systems mainly include: adaptive inertia control (adaptive J control), alternating inertia and damping control (alternating J and D control), P These two control methods have the following disadvantages:

[0090] First, although the traditional phase-locked loop (PLL) is removed, the traditional PI regulator (proportional-integral regulator) is still needed in the grid-connected control loop to ensure the stability of the connection with the grid. The application of the PI controller increases the complexity of the system, and multiple adjustments are required in the control part to ensure the performance and stability of the system. In addition, in order to achieve seamless switching of the operating mode, a static circuit breaker is still required, which increases the hardware cost and complexity of the system.

[0091] Second, these two control methods lack the ability to automatically identify islanding modes and require additional controllers to identify islanding conditions, which increases the complexity of the system and may require additional costs and resources to implement this function.

[0092] Third, although the control loop does not need to be changed during the grid-connected mode switching, an additional static circuit breaker is required to achieve seamless switching between grid-connected and off-grid, which increases the hardware cost and complexity of the system and also adds difficulties to system design and deployment.

[0093] In addition, these two control methods select extreme values ​​of the network control parameters at different time intervals, but do not explain the impact of these extreme inertia and damping values ​​on other control loops. In addition, the energy demand in the active control process is not considered in the adaptive control. The specific disadvantages are:

[0094] First, the demand for energy storage is large. These two control methods require real-time calculation of inertia changes in the system and adjustment of the grid-type energy storage device to maintain the transient performance of the system. However, this real-time calculation and adjustment requires a large amount of computing resources and energy storage resources, especially in large systems or complex environments. This demand will greatly increase the cost and energy consumption of the system.

[0095] Second, adaptive inertia control is also prone to cause active power and frequency oscillations. Since adaptive control requires continuous adjustment of inertia, the transient performance of the system may become more complex and unstable. This instability may manifest as violent oscillations of active power and frequency, which in turn affects the performance and stability of the system.

[0096] Third, long response time is also a disadvantage of adaptive inertia control. Since the inertia needs to be calculated and adjusted in real time, the response time of the control system will increase accordingly. This means that the system's adaptability to external changes may be reduced, thus affecting the system's real-time performance.

[0097] In summary, in the adaptive control of these two methods, the active control process has a large demand for energy storage, and the adaptive inertia control is also prone to cause active power and control frequency oscillation. Therefore, how to reduce the demand for energy storage, active power oscillation and control frequency oscillation has become a problem to be solved.

[0098] In view of the above-mentioned defects, an embodiment of the present application provides a control method for a grid-type energy storage system based on virtual inertia and virtual damping. First, the expression after the derivative of the virtual rotor storage energy is transformed based on the target control parameters obtained by applying a small disturbance and the energy consumed by the DC energy storage device. Then, the variable virtual inertia and the variable virtual damping coefficient are calculated respectively with the help of the synchronous machine swing equation or the damping ratio and the target control parameters based on the active power transfer function. Then, the target virtual inertia and the target virtual damping coefficient are calculated respectively based on the target control parameters and the variable virtual inertia or the variable virtual damping coefficient. Finally, the grid-type energy storage system is controlled based on the calculated target virtual inertia and target virtual damping coefficient.

[0099] The scheme of the present application adjusts the virtual inertia and the virtual damping coefficient at the same time to improve the transient performance of the active power loop of the grid-type control, and realizes the effective utilization of the energy of the grid-type energy storage system while ensuring that the active power oscillation and the control frequency oscillation of the grid-type energy storage system meet the international standard conditions, which can reduce the demand for energy storage, active power oscillation and control frequency oscillation, and shorten the time for the active power and control frequency to reach stability (i.e., oscillation time), thereby improving the stability of the grid-type energy storage system and its power system. In addition, the scheme of the present application has the characteristics of high accuracy and stability, and can better meet the needs of modern power systems for efficient, reliable and intelligent control. In addition, the scheme of the present application can eliminate the dependence on PLL, PI regulators and static circuit breakers, and does not require additional controllers to identify islanding conditions, making the synchronization process between the grid-type energy storage system and the power grid simpler, more accurate, and more stable, with strong ease of use and practicality.

[0100] The specific process implemented by this application is introduced below through specific embodiments.

[0101] See also Figure 1 , Figure 1 Schematic diagram of the steps of the control method of the grid-type energy storage system based on virtual inertia and virtual damping provided in the embodiment of the present application. Figure 1 As shown, the method may include the following steps:

[0102] S101, during the operation of the grid-connected energy storage system, a small disturbance is applied to the steady-state value of the control parameter to obtain the target control parameter.

[0103] In some embodiments, a small disturbance signal can be applied during the operation of the grid-type energy storage system to transform the steady-state value of the control parameter to obtain the actual target control parameter. The small disturbance signal is a small disturbance amount, and the steady-state value of the control parameter is the control parameter when the grid-type energy storage system is running stably.

[0104] S102, based on the target control parameter and the energy consumed or supplied by the DC energy storage device, transform the derivative expression of the virtual rotor stored energy to obtain a transformed expression of the virtual rotor stored energy.

[0105] According to one embodiment of the present application, the control parameters include: control frequency, reference frequency, energy consumed or supplied by the DC energy storage device, virtual inertia, and virtual damping coefficient. The expression of the target control parameter is: Among them, ω represents the control frequency, ω n represents the steady-state value of the control frequency, represents the small disturbance of the control frequency, ω0 represents the reference frequency, ω 0n represents the steady-state value of the reference frequency, represents the small disturbance of the reference frequency; E represents the energy consumed or supplied by the DC energy storage device, and E0 represents the steady-state value of the energy consumed or supplied by the DC energy storage device. It represents the small disturbance of energy consumed or supplied by DC energy storage device; J represents virtual inertia, J0 represents the steady-state value of virtual inertia, Indicates variable virtual inertia; D P represents the virtual damping coefficient, D p0 represents the steady-state value of the virtual damping coefficient, represents the variable virtual damping coefficient. The expression of the energy consumed or supplied by the DC energy storage device is Where, E(t) represents the energy consumed or supplied by the DC energy storage device, t represents time, Pm represents the reference active power, and Pe represents the actual output active power. represents a small disturbance of the reference active power, Represents a small disturbance of active power; the expression of virtual rotor storage energy is The derivative of this expression is obtained to obtain the derivative of the virtual rotor storage energy: Based on the target control parameter and the energy consumed or supplied by the DC energy storage device, transforming the derivative expression of the virtual rotor storage energy to obtain the transformed expression of the virtual rotor storage energy may include the following steps:

[0106] Substitute E in the expression of the target control parameter into the expression of the energy consumed or supplied by the DC energy storage device, and derive the energy consumed or supplied by the DC energy storage device to obtain the following expression:

[0107]

[0108] Among them, in expression (1)

[0109] Substituting J and ω in the expression of the target control parameter into the expression after the derivative of the virtual rotor storage energy, the following expression is obtained:

[0110]

[0111] Substituting expression (1) into expression (2), we obtain the following transformed expression of virtual rotor stored energy:

[0112]

[0113] It should be noted that when substituting J and ω in the expression of the target control parameter into the expression after the derivative of the virtual rotor storage energy to calculate the expression (2), the product of the two small disturbances can be ignored, that is, the product of the two small disturbances is set to 0, for example Because it is assumed that the product between two infinitesimal quantities can be ignored in small signal analysis, the specific calculation process will not be introduced in detail here.

[0114] S103, calculating the variable virtual inertia based on the transformed expression of the virtual rotor stored energy and the synchronous machine swing equation, and calculating the variable virtual damping coefficient based on the damping ratio of the active power transfer function and the target control parameter.

[0115] According to one implementation of the present application, the synchronous machine swing equation is: The variable virtual inertia is calculated based on the transformed expression of virtual rotor stored energy and the synchronous machine swing equation, which may include the following steps:

[0116] First, replace D in expression (3) with the expression of the target control parameter P Substituting ω0 into the synchronous machine swing equation, we get the following expression:

[0117]

[0118] Secondly, the expression (4) can be simplified by ignoring the product of the steady-state value of the control parameter (i.e., the DC term) and the small disturbance, that is, setting the product of the DC term and the small disturbance to 0, and obtaining the following expression:

[0119]

[0120] Finally, by changing the virtual inertia in expression (5) Solve and get the variable virtual inertia The expression is as follows:

[0121]

[0122] Where δ represents the load angle, represents a small perturbation of the load angle, The integral is

[0123] According to one embodiment of the present application, the expression of the damping ratio of the active power transfer function (to be introduced in subsequent embodiments) is: ω N represents the natural oscillation frequency, K is a constant, Von represents the rated output voltage of the grid-type energy storage system, Vgn represents the grid voltage, and Xs represents the grid impedance. The variable virtual damping coefficient is calculated based on the damping ratio of the active power transfer function and the target control parameter, which may include the following steps:

[0124] First, transform the expression of the damping ratio of the active power transfer function, that is, solve the damping ratio Dp, and obtain the following expression:

[0125] D P =2Jζω N (7);

[0126] Then substitute Dp and J in the expression of the target control parameter into expression (7) and ignore the steady-state value of the control parameter (i.e., the DC term), that is, let D p0 and J0 is 0, the variable virtual damping coefficient is calculated The expression is as follows:

[0127]

[0128] In order to simplify the original expression (8), ω N0 Substituting as the intermediate variable into the original expression (8) yields the above expression (8), represents the natural oscillation frequency ω N Small disturbance amount.

[0129] S104, based on the target control parameter and the variable virtual inertia, the target virtual inertia is calculated, and based on the target control parameter and the variable virtual damping coefficient, the target virtual damping coefficient is calculated.

[0130] Figure 2 is the target virtual inertia J and target virtual damping coefficient D provided in the embodiment of the present application P According to one embodiment of the present application, the target virtual inertia is calculated based on the target control parameter and the variable virtual inertia, which may include the following steps:

[0131] In the expression based on the target control parameter and variable virtual inertia The target virtual inertia J is calculated by using the expression (6). The expression of the target virtual inertia J is as follows:

[0132]

[0133] According to an embodiment of the present application, based on the target control parameter and the variable virtual damping coefficient, calculating the target virtual damping coefficient may include the following steps:

[0134] In the expression based on the target control parameter and variable virtual damping coefficient The target virtual damping coefficient D is calculated by using the expression (8) P , target virtual damping coefficient D P The expression is as follows:

[0135]

[0136] Among them, D P0 is a specific value determined according to the power grid. When the power grid frequency changes by 2%, the actual active power changes by 100%. Based on this change relationship and the transfer function of active power, D can be determined. P0 .

[0137] It should be noted that in order to reduce the energy storage demand of the grid-type energy storage system, it is necessary to be slightly underdamped when designing the grid-type energy storage system, that is, the damping ratio ζ is slightly smaller than 1. The specific determination process of the damping ratio ζ will be introduced in subsequent embodiments.

[0138] According to one embodiment of the present application, the method may further include the following steps:

[0139] First, substitute Dp in expression (10) into the damping frequency ω d The damping frequency ω is calculated by d The J in the expression is then used as the J0 in expression (9), and finally the J in expression (9) is calculated based on the J0, and finally the target virtual inertia is calculated. d The expression is

[0140] S105, controlling the grid-type energy storage system based on the target virtual inertia and the target virtual damping coefficient.

[0141] In some embodiments, Figure 3 is a control block diagram of a grid-type energy storage system provided in an embodiment of the present application. The target virtual inertia and the target virtual damping coefficient can be substituted into Figure 3 The grid-type energy storage system shown in the figure is controlled to improve the stability of the grid-type energy storage system. The grid-type control includes flexible VSG (Virtual Synchronous Generator) control, and the flexible VSG control includes: voltage and current double closed-loop control, active power control and reactive voltage control.

[0142] According to an embodiment of the present application, the topology of the meshed converter is as follows: Figure 4 As shown, the corresponding active power control small signal block diagram is as follows Figure 5 As shown. The active power transfer function, that is, the transfer function between the active power and the reference active power is:

[0143]

[0144] in, is a small disturbance of the reference active power, is the small disturbance of the actual output active power; J is the virtual inertia, Dp is the virtual damping coefficient, ω0 is the grid-type reference control frequency, s is the complex frequency variable of the Laplace transform in the active power transfer function; K is a constant, Von represents the rated output voltage of the grid-type energy storage system, Vgn represents the grid voltage, and Xs represents the grid impedance.

[0145] The transfer function of the grid-type control frequency and the reference active power is:

[0146]

[0147] The transfer function between active power and reference active power is a second-order system, and its natural oscillation frequency ω N , damping ratio ζ and damping frequency ω d The expression is as follows:

[0148]

[0149] The response equation of active power when the reference active power changes stepwise is as follows:

[0150]

[0151] in,

[0152] The transient response parameters of the grid-type energy storage system include: rise time t r , peak time t p , stabilization time t s And the peak overshoot M p , the expressions of various transient response parameters are as follows:

[0153]

[0154] According to an implementation of the present application, the transient response characteristics of the active power circuit of the grid-type energy storage system, that is, the transient performance, that is, the dynamic performance, can be analyzed. Using the control variable method, when one parameter of the virtual inertia and the virtual damping coefficient is constant and the other parameter is changed, the influence of the changed parameter on the transient performance of the grid-type energy storage system is analyzed.

[0155] In one embodiment, the influence of the virtual damping coefficient on the transient performance of the grid-type energy storage system can be analyzed when the virtual inertia is constant and the virtual damping coefficient is changed. p , stabilization time t s And the peak overshoot M p For the virtual damping coefficient D P The derivative of DP Impact on active power transient response.

[0156] Correspondingly, according to the expressions of transient response parameters, the peak time t p , stabilization time t s And the peak overshoot M p For the virtual damping coefficient D P The derivative of is:

[0157]

[0158] From this expression, it can be seen that the peak time t p is along with the virtual damping coefficient D P Therefore, as the virtual damping coefficient D P The increase in peak time t p However, the stabilization time t s and peak overshoot M p All of them are related to the virtual damping coefficient D P Therefore, as the virtual damping coefficient D P The increase of the stabilization time t s and peak overshoot M p Will decrease.

[0159] The influence of the change of virtual damping coefficient on the transient response of active power is as follows: Figure 6 As shown in the figure, the three curves represent the active power transient response of the grid-type energy storage system under different virtual damping coefficients. As the virtual damping coefficient increases, the peak overshoot and the stabilization time both decrease, but the peak time increases. The black arrow indicates the direction of increasing virtual damping coefficient, and the brown curve indicates the active power oscillation when the virtual damping coefficient is the smallest. When the virtual damping coefficient is the smallest, the peak overshoot is the largest, and the stabilization time (the time for active power to reach stability, the steady-state value of active power is stable within the preset range) is the longest, that is, the active power oscillation time is the longest; the red curve indicates the active power oscillation when the virtual damping coefficient is at an intermediate value. When the virtual damping coefficient is at an intermediate value, the peak overshoot and the stabilization time both decrease, but the peak time increases; the blue curve indicates the active power oscillation when the virtual damping coefficient is the largest. When the virtual damping coefficient is the largest, the peak overshoot is the smallest, the stabilization time is the shortest, but the peak time is the longest. In general, increasing the virtual damping coefficient can reduce the oscillation amplitude of active power and reduce the stabilization time, but it will delay the time to reach the peak.

[0160] Similarly, the expression of the transfer function between the grid-type control frequency and the reference active power can be used to analyze the influence of the virtual damping coefficient on the grid-type control frequency. As the virtual damping coefficient increases, the peak time, peak overshoot and stabilization time of the control frequency are reduced. The influence of the change of the virtual damping coefficient on the transient response of the control frequency of the grid-type energy storage system is shown in Figure 7 As shown, the three curves represent the control frequency transient response of the grid-type energy storage system under different virtual damping coefficients. Figure 7 The three curves shown are Figure 6 The three curves shown have similar meanings and can be reasonably inferred, so they will not be repeated here.

[0161] In another embodiment, the influence of virtual inertia on the transient performance of the grid-type energy storage system can be analyzed when the virtual damping coefficient is constant and the virtual inertia is variable. When the virtual damping coefficient is constant and the virtual inertia is variable, the influence of virtual inertia on the transient response of active power can also be analyzed by using the derivative of the transient performance parameter to the virtual inertia.

[0162] Correspondingly, according to the expressions of transient response parameters, the peak time t p , stabilization time t s And the peak overshoot M p The derivative of the virtual inertia J is:

[0163]

[0164] From this expression, it can be seen that the peak time, stabilization time and peak overshoot of active power are all functions that increase with the increase of virtual inertia. Therefore, as the virtual inertia increases, the peak time, stabilization time and peak overshoot will increase. The impact of virtual inertia change on the transient response of active power is as follows: Figure 8 As shown, the three curves represent the active power transient response of the grid-connected energy storage system under different virtual inertias. Figure 8 The three curves shown are Figure 6 The three curves shown have similar meanings and can be reasonably inferred, so they will not be repeated here.

[0165] Similarly, the expression of the transfer function between the grid-type control frequency and the reference active power can also be used to analyze the influence of virtual inertia on the grid-type control frequency. The peak time and stabilization time of the control frequency increase with the increase of virtual inertia, while the peak overshoot decreases with the increase of virtual inertia. The influence of virtual inertia change on the transient response of the control frequency of the grid-type energy storage system is shown in Fig. 9 As shown, the three curves represent the control frequency transient response of the grid-type energy storage system under different virtual inertias. Fig. 9 The three curves shown are Figure 6The three curves shown have similar meanings and can be reasonably inferred, so they will not be repeated here.

[0166] Therefore, by analyzing the impact of virtual inertia and virtual damping coefficient on the transient performance of the grid-connected energy storage system, it can be determined that both parameters need to be adjusted to suppress active power and control frequency oscillation. The specific process of adjusting the parameters has been described in the above embodiment and will not be repeated here.

[0167] According to one embodiment of the present application, the method may further include the following steps:

[0168] Based on the energy consumed or supplied by the DC energy storage device, the energy absorbed or consumed by the DC energy storage device in the critical damping grid energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system are calculated; based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system, the damping ratio is determined.

[0169] According to an implementation of the present application, in order to make the energy of the grid-type energy storage system meet the support requirements of the virtual inertia and virtual damping coefficient, the influence of the damping ratio on the energy absorbed by the DC energy storage device can be analyzed to provide a theoretical basis for the parameter design of the grid-type energy storage system. and The area between them, combined with the response equation of active power when the reference active power changes stepwise, can be used to obtain the expression of energy consumed or supplied by the DC energy storage device:

[0170]

[0171] Among them, ω d represents the damping frequency, ζ represents the damping ratio, φ is the intermediate variable, Determining the damping ratio based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system may include the following steps:

[0172] First, substituting ζ=1 into the expression of energy consumed or supplied by the DC energy storage device, the following expression of energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system (ζ=1, the grid-type energy storage system is in the critical damping state) is obtained:

[0173]

[0174] Among them, when t→∞, the expression of the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system during the active power oscillation (i.e., active power interference) can be obtained as follows:

[0175]

[0176] Secondly, let t = t r Substituting the expression of energy consumed or supplied by the DC energy storage device, the following is obtained: The active power first reaches a balanced state (that is, the rise time of the angular velocity of the control loop of the grid-type control ends, corresponding to Figure 7 and Fig. 9 The expression of the energy absorbed or consumed by the DC energy storage device in the under-damped grid-type energy storage system (0<ζ<1, the grid-type energy storage system is in an under-damped state) at the moment when the acceleration of the angular velocity of the control loop in the control frequency transient response diagram shown is 0:

[0177]

[0178] Among them, when t r =(π-φ) / ω d When , the expression of energy absorbed or consumed by the DC energy storage device in the underdamped grid energy storage system is as follows:

[0179]

[0180] Finally, the absorption energy diagram ( Fig.10 ) and the absorption energy diagram determined by expression (14) ( Fig.11 ), determine the damping ratio.

[0181] In one embodiment, Fig.10 Schematic diagram of the critical damping system absorbing energy provided by the embodiment of the present application. Fig.10 As shown in the figure, the reference active power Pm is a ray parallel to the horizontal axis, and the active power Pe is a curve. As time goes by, the active power gradually increases and eventually overlaps with the reference active power, indicating that the active power reaches a balanced state. The shaded part composed of the vertical axis, active power Pe and reference active power Pm is the energy absorbed by the critical damping system.

[0182] In another embodiment, Fig.11 Schematic diagram of energy absorption by an underdamped system provided in an embodiment of the present application. Fig.11As shown in the figure, the active power is less than the reference active power (i.e. Pe<Pm) for a period of time. As time goes by, the active power gradually increases. For a period of time, the active power is greater than the reference active power (i.e. Pe>Pm). Then the active power gradually decreases. For a period of time, the active power is less than the reference active power (i.e. Pe<Pm). Finally, the active power coincides with the reference active power (i.e. Pe=Pm), indicating that the active power reaches a balanced state. The red shaded part is the energy absorbed by the critical damping system, and the blue shaded part is the energy released by the critical damping system. The control loop absorbs energy when accelerating and releases energy when decelerating. Among them, when Pe>Pm, it indicates that the active power output of the grid-type energy storage system has an overshoot phenomenon.

[0183] Exemplarily, when the grid-type energy storage system is in a critical damping state, there is no overshoot in the active power output, but the system response speed is slow and requires more energy storage than the underdamped system. Therefore, when designing a grid-type energy storage system, it is necessary to make a trade-off between the underdamped system and the critical damped system. In order to reduce the energy storage demand of the grid-type energy storage system and shorten the oscillation time of the active power (i.e., the time for the active power to reach stability), the system needs to be slightly underdamped during design, that is, the damping ratio ζ is slightly smaller than 1 (e.g., ζ = 0.707), and the active power oscillation is kept within an acceptable range.

[0184] It should be noted that according to existing international standards, the acceptable range of active power oscillation is: the maximum value of the active power change ΔP should not be less than 10% P N (rated power), and should not be greater than 30% P N , the response time should not be greater than 0.5s. During the damping control response, the oscillating energy flow W provided by the energy storage should be less than 0.

[0185] It should be noted that the control method of the grid-type energy storage system based on virtual inertia and virtual damping provided in the embodiment of the present application can also be used for subsequent research on the control of multi-grid-type energy storage systems.

[0186] The control method of the grid-type energy storage system based on virtual inertia and virtual damping provided in the embodiment of the present application first transforms the expression after the derivative of the virtual rotor storage energy based on the target control parameter obtained by applying a small disturbance and the energy consumed by the DC energy storage device, and then calculates the variable virtual inertia and the variable virtual damping coefficient respectively with the help of the synchronous machine swing equation or the damping ratio and the target control parameter based on the active power transfer function, then calculates the target virtual inertia and the target virtual damping coefficient respectively based on the target control parameter and the variable virtual inertia or the variable virtual damping coefficient, and finally controls the grid-type energy storage system based on the calculated target virtual inertia and target virtual damping coefficient.

[0187] The scheme of the present application adjusts the virtual inertia and the virtual damping coefficient at the same time to improve the transient performance of the active power loop of the grid-type control, and realizes the effective utilization of the energy of the grid-type energy storage system while ensuring that the active power oscillation and the control frequency oscillation of the grid-type energy storage system meet the international standard conditions, which can reduce the demand for energy storage, active power oscillation and control frequency oscillation, and shorten the time for the active power and control frequency to reach stability (i.e., oscillation time), thereby improving the stability of the grid-type energy storage system and its power system. In addition, the scheme of the present application has the characteristics of high accuracy and stability, and can better meet the needs of modern power systems for efficient, reliable and intelligent control. In addition, the scheme of the present application can eliminate the dependence on PLL, PI regulators and static circuit breakers, and does not require additional controllers to identify islanding conditions, making the synchronization process between the grid-type energy storage system and the power grid simpler, more accurate, and more stable, with strong ease of use and practicality.

[0188] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean 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 application.

[0189] Corresponding to the method of the above embodiment, Fig.12 It is a structural schematic diagram of a control device of a grid-type energy storage system based on virtual inertia and virtual damping provided in an embodiment of the present application. For the sake of convenience of explanation, only the parts related to the embodiment of the present application are shown.

[0190] Reference Fig.12 , the device comprises:

[0191] An applying unit 121 is used to apply a small disturbance to the steady-state value of the control parameter during the operation of the grid-type energy storage system to obtain a target control parameter;

[0192] A transformation unit 122, configured to transform the derivative of the virtual rotor storage energy based on the target control parameter and the energy consumed or supplied by the DC energy storage device to obtain a transformed expression of the virtual rotor storage energy;

[0193] A first calculation unit 123 is used to calculate the variable virtual inertia based on the transformed expression of the virtual rotor stored energy and the synchronous machine swing equation, and calculate the variable virtual damping coefficient based on the damping ratio of the active power transfer function and the target control parameter;

[0194] A second calculation unit 124 is used to calculate a target virtual inertia based on the target control parameter and the variable virtual inertia, and to calculate a target virtual damping coefficient based on the target control parameter and the variable virtual damping coefficient;

[0195] The control unit 125 is used to control the grid-type energy storage system based on the target virtual inertia and the target virtual damping coefficient.

[0196] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0197] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by 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 embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0198] Fig.13 This is a schematic diagram of the structure of an electronic device 13 provided in an embodiment of the present application. Fig.13 As shown, the electronic device 13 of this embodiment includes: at least one processor 131 ( Fig.13 Only one is shown in the figure), a memory 133, and a computer program 132 stored in the memory 133 and executable on at least one processor 131, and when the processor 131 executes the computer program 132, the steps in the above method embodiment are implemented.

[0199] The electronic device 13 may be a controller or other device in a grid-type energy storage system. The electronic device 13 may include, but is not limited to, a processor 131 and a memory 133. Those skilled in the art will appreciate that Fig.13 It is only an example of the electronic device 13 and does not constitute a limitation on the electronic device 13. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, it may also include input and output devices, network access devices, etc.

[0200] The processor 131 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), 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, etc.

[0201] In some embodiments, the memory 133 may be an internal storage unit of the electronic device 13, such as a hard disk or memory of the electronic device 13. In other embodiments, the memory 133 may also be an external storage device of the electronic device 13, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital card (SecureDigital, SD), a flash card (Flash Card), etc. equipped on the electronic device 13. Further, the memory 133 may also include both an internal storage unit of the electronic device 13 and an external storage device. The memory 133 is used to store an operating system, an application program, a boot loader (Boot Loader), data, and other programs, such as program codes of a computer program. The memory 133 may also be used to temporarily store data that has been output or is to be output.

[0202] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, when the present application implements all or part of the processes in the above-mentioned embodiment method, it can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps applied to the method embodiment can be implemented. Among them, the computer program includes a computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may at least include: any entity or device that can carry the computer program code to the computing device / electronic device, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electric carrier signal, a telecommunication signal, and a software distribution medium, such as a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, a computer-readable storage medium cannot be an electric carrier signal and a telecommunication signal.

[0203] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0204] An embodiment of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes the steps in the above-mentioned method embodiments.

[0205] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0206] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0207] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. The device / electronic device embodiments described above are merely schematic, and the division of the above modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, and some features can be ignored and not executed. Another point is that the indirect coupling, direct coupling or communication connection between each other shown or discussed can be an indirect coupling, direct coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0208] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0209] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A control method for a grid-type energy storage system based on virtual inertia and virtual damping, characterized in that: The method comprises: During the operation of the grid-type energy storage system, a small disturbance is applied to the steady-state value of the control parameter to obtain the target control parameter; Based on the target control parameter and the energy consumed or supplied by the DC energy storage device, transforming the derivative expression of the virtual rotor storage energy to obtain a transformed expression of the virtual rotor storage energy; The variable virtual inertia is calculated based on the transformed expression of the virtual rotor stored energy and the synchronous machine swing equation, and the variable virtual damping coefficient is calculated based on the damping ratio of the active power transfer function and the target control parameter; Based on the target control parameter and the variable virtual inertia, a target virtual inertia is calculated; based on the target control parameter and the variable virtual damping coefficient, a target virtual damping coefficient is calculated; Based on the target virtual inertia and the target virtual damping coefficient, the grid-type energy storage system is controlled.

2. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 1 is characterized in that: The control parameters include: control frequency, reference frequency, energy consumed or supplied by the DC energy storage device, virtual inertia and virtual damping coefficient. The expression of the target control parameter is: Among them, ω represents the control frequency, ω n represents the steady-state value of the control frequency, represents the small disturbance of the control frequency, ω0 represents the reference frequency, ω 0n represents the steady-state value of the reference frequency, represents the small disturbance of the reference frequency, E represents the energy consumed or supplied by the DC energy storage device, E0 represents the steady-state value of the energy consumed or supplied by the DC energy storage device, It represents the small disturbance of energy consumed or supplied by the DC energy storage device, J represents the virtual inertia, J0 represents the steady-state value of the virtual inertia, Indicates variable virtual inertia, D P represents the virtual damping coefficient, D p0 represents the steady-state value of the virtual damping coefficient, represents the variable virtual damping coefficient; the expression of the energy consumed or supplied by the DC energy storage device is Where, E(t) represents the energy consumed or supplied by the DC energy storage device, t represents time, Pm represents the reference active power, and Pe represents the actual output active power. represents a small disturbance of the reference active power, Represents a small disturbance of active power; the expression of virtual rotor storage energy is The derivative expression of virtual rotor storage energy is: Based on the target control parameter and the energy consumed or supplied by the DC energy storage device, the derived expression of the virtual rotor storage energy is transformed to obtain a transformed expression of the virtual rotor storage energy, including: Substituting E in the expression of the target control parameter into the expression of the energy consumed or supplied by the DC energy storage device, and taking the derivative of the energy consumed or supplied by the DC energy storage device, the following expression is obtained: Among them, in expression (1) Substituting J and ω in the expression of the target control parameter into the expression after the derivative of the virtual rotor storage energy, the following expression is obtained: Substituting expression (1) into expression (2), we obtain the following transformed expression of virtual rotor stored energy:

3. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 2 is characterized in that: The synchronous machine swing equation is The variable virtual inertia is calculated based on the transformed expression of virtual rotor stored energy and the synchronous machine swing equation, including: The D in expression (3) and the expression of the target control parameter is P Substituting ω0 into the synchronous machine swing equation, we get the following expression: Ignoring the product of the steady-state value of the control parameter and the small disturbance in expression (4), simplifying expression (4) yields the following expression: The variable virtual inertia is calculated according to expression (5), and the expression of the variable virtual inertia is as follows: Where δ represents the load angle, represents a small perturbation of the load angle, The integral is 4. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 3 is characterized in that: The expression of the damping ratio of the active power transfer function is ω N represents the natural oscillation frequency, K is a constant, Von represents the rated output voltage of the grid-type energy storage system, Vgn represents the grid voltage, and Xs represents the grid impedance; The variable virtual damping coefficient is calculated based on the damping ratio of the active power transfer function and the target control parameter, including: Transforming the expression of the damping ratio of the active power transfer function, we get the following expression: D P =2J live N (7); Substituting Dp and J in the expression of the target control parameter into expression (7) and ignoring the steady-state value of the control parameter, the variable virtual damping coefficient is calculated and the expression of the variable virtual damping coefficient is as follows: Among them, ω N0 is the intermediate variable, A small perturbation that represents the natural oscillation frequency.

5. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 4 is characterized in that: Calculating a target virtual inertia based on the target control parameter and the variable virtual inertia includes: Based on J in the expression of the target control parameter and the expression of the variable virtual inertia, the target virtual inertia is calculated and obtained. The expression of the target virtual inertia is as follows:

6. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 5 is characterized in that: Based on the target control parameter and the variable virtual damping coefficient, a target virtual damping coefficient is calculated, including: Based on Dp in the expression of the target control parameter and the expression of the variable virtual damping coefficient, the target virtual damping coefficient is calculated and obtained. The expression of the target virtual damping coefficient is as follows: Among them, D P0 Determined by the power grid.

7. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 6 is characterized in that: The method further comprises: Substitute Dp in expression (10) into the expression of damping frequency to calculate J in the expression of damping frequency; where the expression of damping frequency is: Let J in the expression of damping frequency be J0 in expression (9); J in expression (9) is calculated based on J0 in expression (9).

8. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 7 is characterized in that: The method further comprises: Based on the energy consumed or supplied by the DC energy storage device, calculate the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system; The damping ratio is determined based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system.

9. The control method of the grid-type energy storage system based on virtual inertia and virtual damping according to claim 8 is characterized in that: The expression for the energy consumed or supplied by a DC energy storage device is: Among them, ω d represents the damping frequency, ζ represents the damping ratio, φ is the intermediate variable, Determining the damping ratio based on the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system and the energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system includes: Substituting ζ=1 into the expression of energy consumed or supplied by the DC energy storage device, the following expression of energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system is obtained: Wherein, when t→∞, the expression of the energy absorbed or consumed by the DC energy storage device in the critical damping grid-type energy storage system is as follows: Set t = t r Substituting the expression of energy consumed or supplied by the DC energy storage device into the expression, the following expression of energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system is obtained: Among them, when t r =(π-φ) / ω d When , the expression of energy absorbed or consumed by the DC energy storage device in the underdamped grid-type energy storage system is as follows: The damping ratio is determined based on the absorption energy diagram determined by expression (12) and the absorption energy diagram determined by expression (14).

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the control method of the grid-type energy storage system based on virtual inertia and virtual damping described in any one of claims 1-9 is implemented.

Images