Cascaded energy storage fast inter-area equalization control method and system

Abstract

The application belongs to the technical field of energy storage equalization control, and specifically discloses a cascaded energy storage fast inter-phase equalization control method and system, which comprises the following steps: injecting a zero sequence voltage into a three-phase modulation signal output by a power control loop to construct an inter-phase power deviation model; taking actually measured three-phase output currents as input to obtain a zero sequence voltage for realizing inter-phase output power equalization based on output current phasors; replacing the equalization object with the SOC average of each phase battery cluster to obtain a zero sequence voltage required for realizing inter-phase SOC equalization based on output current phasors; superimposing the zero sequence voltage and the three-phase modulation signal output by the power control loop, and generating a PWM control signal of each switching device by using a carrier phase-shifted modulation mode. The application constructs a zero sequence voltage injection model based on a current phasor synthesis principle, is simple in calculation, and realizes fast inter-phase equalization under different operating conditions such as bidirectional charging and discharging and reactive power support.

Description

Technical Field

[0001] This invention relates to the field of energy storage equalization control technology, and in particular to a fast phase-to-phase equalization control method and system for cascaded energy storage. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Cascaded H-Bridge Battery Energy Storage System (CHB-BESS) has become an important technology in the field of large-scale energy storage due to its advantages such as modularity, high voltage output capability, and direct connection to medium-voltage power distribution networks. However, it generally faces the problem of state of charge (SOC) imbalance among battery clusters during operation.

[0004] Based on the spatial relationship of the affected battery packs, the SOC imbalance of the battery clusters in a cascaded H-bridge energy storage system can be divided into two categories: in-phase SOC imbalance and inter-phase SOC imbalance. Inter-phase SOC imbalance originates from multiple factors, including manufacturing differences, temperature variations, battery aging, and asymmetrical three-phase loads. If not suppressed in time, it will lead to decreased submodule utilization, limited modulation duty cycle, compressed charge / discharge range, and even overmodulation and potential battery failure risks. Therefore, achieving rapid and stable inter-phase SOC balancing is of great significance for improving the reliability, safety, and energy utilization of CHB-BESS.

[0005] Existing phase-to-phase SOC equalization methods typically employ a zero-sequence voltage injection strategy. By adjusting the common component of the three-phase modulation signals, a controllable difference in the three-phase output power is created, thereby achieving SOC balance. However, this method requires trigonometric function calculations of the zero-sequence voltage amplitude and phase, resulting in high control algorithm complexity. Furthermore, traditional zero-sequence voltage often uses a fixed amplitude mode, limiting the equalization speed. Over-modulation boundaries are not adequately considered during the equalization process, and the selection of equalization coefficients lacks a theoretical upper limit. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a cascaded energy storage fast phase-to-phase equalization control method and system, which can effectively reduce the computational load of the controller and improve the real-time control capability of the system. By selecting the optimal phase-to-phase equalization coefficient within the modulation constraint range, fast phase-to-phase SOC convergence under different operating conditions is achieved.

[0007] In some implementations, the following technical solutions are adopted:

[0008] A method for rapid phase-to-phase equalization control of cascaded energy storage includes:

[0009] Acquire the SOC information, output voltage and current information of each phase battery cluster in the cascaded energy storage system;

[0010] A zero-sequence voltage with a set amplitude and phase is injected into the three-phase modulation signal output from the power control loop. u 0. Construct an interphase power deviation model; using the measured three-phase output current as input, obtain the zero-sequence voltage that achieves interphase output power balance based on the output current phasor;

[0011] Establish the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replace the balancing object with the average SOC of each battery cluster, and obtain the zero-sequence voltage required to achieve inter-phase SOC balance based on the output current phasor.

[0012] The zero-sequence voltage is superimposed on the three-phase modulation signal output by the power control loop, and a PWM control signal for each switching device is generated using carrier phase-shift modulation.

[0013] As a further solution, the phase-to-phase power deviation model is specifically as follows:

[0014] ;

[0015] in, For the increased output power per phase, This represents the total reference output power of the system. This represents the reference output power of phase j. I g It is the root mean square value of the output current of the cascaded energy storage system. Represents zero-sequence voltage u The magnitude of the projection of 0 onto the three-phase output current direction.

[0016] As a further approach, a zero-sequence voltage is obtained that achieves phase-to-phase output power balance based on the output current phasor, specifically as follows:

[0017] ;

[0018] in, Represents the given apparent power. This represents the total reference output power of the system. This represents the reference output power of phase j. , , These are the instantaneous currents output by the three phases A, B, and C of the cascaded energy storage system.

[0019] As a further approach, a relationship is established between the reference output power of each phase and the average SOC of the corresponding battery cluster, specifically:

[0020] ;

[0021] in, This represents the total reference output power of the system. This represents the reference output power of phase j. SOC avj This represents the average SOC value of the j-th phase battery cluster. SOC T Representing all SOC avj The sum, .

[0022] As a further solution, the balancing object is replaced with the average SOC of each battery cluster, resulting in the zero-sequence voltage required to achieve inter-phase SOC balance based on the output current phasor, specifically:

[0023] ;

[0024] in, K 1 represents the phase equilibrium coefficient, which determines the equilibrium speed; Represents the given apparent power. This represents the total reference output power of the system. I g It is the root mean square value of the output current of the cascaded energy storage system; SOC avj This represents the average SOC value of the j-th phase battery cluster. SOC T Representing all SOC avj The sum of .

[0025] As a further solution, the interphase balance coefficient K 1. Adjust according to actual operating conditions. In order to achieve rapid phase-to-phase SOC balance and prevent overmodulation, the zero-sequence voltage needs to meet the following conditions:

[0026] ;

[0027] in, express j The modulation signal after phase injection of zero-sequence voltage, Indicates the output of the power control loop. j The phase modulation signal, This indicates the number of H-bridge submodules contained in each phase of a cascaded energy storage system. This indicates the voltage of the DC-side battery cluster of the H-bridge submodule.

[0028] As a further solution, the interphase balance coefficient K The range of values ​​for 1 is:

[0029] ;

[0030] in, Where is the grid voltage amplitude, and S represents the overall phase-to-phase SOC imbalance of the cascaded energy storage system. Let S be the amplitude.

[0031] In other embodiments, the following technical solutions are adopted:

[0032] A cascaded energy storage rapid phase-to-phase equalization control system includes:

[0033] The data acquisition module is configured to acquire the SOC information, output voltage and current information of each phase battery cluster in the cascaded energy storage system.

[0034] The power deviation construction module is configured to inject a zero-sequence voltage of a set amplitude and phase into the three-phase modulated signal output from the power control loop. u 0. Construct an interphase power deviation model; using the measured three-phase output current as input, obtain the zero-sequence voltage that achieves interphase output power balance based on the output current phasor;

[0035] The equalization conversion module is configured to establish the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replace the equalization object with the average SOC of each battery cluster, and obtain the zero-sequence voltage required to achieve inter-phase SOC balance based on the output current phasor.

[0036] The switching control module is configured to modulate the zero-sequence voltage with a three-phase modulation signal output from the power control loop. u j The signals are superimposed and a carrier phase-shift modulation method is used to generate the PWM control signal for each switching device.

[0037] In other embodiments, the following technical solutions are adopted:

[0038] A terminal device includes a processor and a memory, wherein the processor is used to implement instructions; and the memory is used to store multiple instructions, the instructions being adapted to be loaded and executed by the processor to perform the aforementioned cascaded energy storage fast phase-to-phase equalization control method.

[0039] In other embodiments, the following technical solutions are adopted:

[0040] A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the above-described cascaded energy storage fast phase-to-phase equalization control method.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] (1) The present invention constructs a zero-sequence voltage injection model based on the principle of current phasor synthesis. By selecting the optimal interphase equalization coefficient within the modulation constraint range, it achieves fast interphase SOC convergence under different operating conditions. Furthermore, the interphase SOC equalization can remain stable and effective under bidirectional power flow and reactive power support scenarios.

[0043] (2) The zero-sequence voltage calculation of the present invention relies only on basic algebraic operations, avoiding the complex trigonometric function operations in traditional methods, thereby effectively reducing the computational load of the controller and improving the real-time control capability of the system. The method is based on the current phasor model and can be applied to operating modes with reactive power support. It is not affected by the coupling characteristics of active and reactive power and has strong adaptability to operating conditions.

[0044] (3) By achieving rapid convergence of the average SOC of the three-phase battery cluster, the present invention can reduce the risk of overcharging and over-discharging of the battery cluster, improve the energy utilization rate and operational safety of the energy storage system, and thus improve the overall efficiency, lifespan and reliability of the system.

[0045] Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the main circuit structure of the cascaded H-bridge energy storage system in an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the three-phase voltage and current phasor relationship after zero-sequence voltage is injected in an embodiment of the present invention;

[0048] Figure 3 As described in the embodiments of the present invention K 1max With the magnitude of the grid voltage V m The curve showing the variation of the degree of SOC imbalance between phases;

[0049] Figure 4 This is a schematic diagram showing the superposition of zero-sequence voltage and the modulation signal output by the power control loop of the cascaded energy storage system in an embodiment of the present invention;

[0050] Figure 5 The simulation results of the fast phase-to-phase SOC equalization method of the present invention under the conditions of 10kV, 4MW (active power), and 3MW (reactive power) are shown. Detailed Implementation

[0051] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0053] Example 1

[0054] In one or more embodiments, a fast phase-to-phase equilibrium control method for cascaded energy storage is disclosed, specifically including the following process:

[0055] S101: Obtain the SOC information, output voltage and current information of each phase battery cluster in the cascaded energy storage system.

[0056] Specifically, Figure 1 This is the main circuit topology diagram of a cascaded H-bridge energy storage system. The system adopts a star structure, consisting of three phases connected through a filter inductor. L f It is connected to the power grid. Each phase consists of N sub-modules connected in series. Each sub-module includes a battery cluster, a DC-side filter inductor, a DC-side filter capacitor, and an H-bridge structure composed of four power switching devices.

[0057] Among them, SOC jk The state of charge (SOC) of the k-th submodule battery cluster in phase j (j∈{a,b,c}) can be obtained from the battery management system; the output current of each phase is... i j The grid voltage for each phase is v j This can be obtained from a current sensor and a voltage sensor, respectively.

[0058] S102: Three-phase modulation signal output to the power control loop u j A zero-sequence voltage with a set amplitude and phase is injected into (j∈a,b,c). u 0. Construct an interphase power deviation model; using the measured three-phase output current as input, obtain the zero-sequence voltage that achieves interphase output power balance based on the output current phasor.

[0059] In this embodiment, to achieve interphase SOC equalization, a zero-sequence voltage with a specific amplitude and phase needs to be injected into the modulation signal of the three-phase output. u 0. The phase diagram of the energy storage system after injecting zero-sequence voltage is as follows: Figure 2 As shown.

[0060] Based on the power balance principle and combining the phasor relationship between the output voltage and output current of each phase in a cascaded energy storage system, the interphase power deviation model is constructed as follows:

[0061] Increased output power per phase It can be represented as:

[0062] (1)

[0063] in, This represents the total reference output power of the system. This represents the reference output power of phase j. It is the root mean square value of the output current of the cascaded energy storage system. express Projection in the direction of the three-phase output current.

[0064] Based on the three-phase power balance principle, the zero-sequence voltage can be obtained. The projection in the direction of the three-phase output current is:

[0065] (2)

[0066] in, This is the effective value of the grid voltage. This represents the phase angle between the three-phase output current and the grid voltage. This represents the given apparent power.

[0067] Therefore, zero-sequence voltage Projection in the direction of the three-phase instantaneous output current It can be represented as:

[0068] (3)

[0069] in, As a phasor, it can characterize the direction of the output current of an energy storage system to a certain extent.

[0070] Using the measured three-phase output current as input, and based on phasor synthesis, the zero-sequence voltage that achieves phase-to-phase output power balance using the output current phasor as a reference can be obtained as follows:

[0071] (4)

[0072] in, , , These are the instantaneous currents output by the three phases A, B, and C of the cascaded energy storage system.

[0073] S103: Establish the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replace the balancing object with the average SOC of each battery cluster, and obtain the zero-sequence voltage required to achieve inter-phase SOC balance based on the output current phasor.

[0074] In this embodiment, based on the ability to achieve phase-to-phase output power balance, in order to further achieve phase-to-phase SOC balance among battery packs, the relationship between the output power of each phase and the average SOC of the corresponding battery pack is established as follows:

[0075] (5)

[0076] in, SOC avj This represents the average SOC value of the j-th phase battery pack. SOC T Representing all SOC avj The sum, .

[0077] Replacing power equalization with SOC equalization yields the zero-sequence voltage required to achieve interphase SOC balance based on the output current phasor. for:

[0078] (6)

[0079] in, ζ j This is the phase imbalance factor, representing the degree of phase SOC imbalance; K 1 is the phase-to-phase balance coefficient, which determines the balancing speed. Its value is limited by the overshoot boundary and the power output capability of the submodule.

[0080] During the charging process of the grid to the energy storage system, the zero-sequence voltage synthesized in this embodiment This zero-sequence voltage is dynamically generated based on the SOC and output current information of each phase battery cluster. The polarity of this zero-sequence voltage is automatically adjusted according to the direction of the output current, ensuring that during charging, when the SOC of a certain phase is low... The phase with a higher SOC receives a larger charging current, while the phase with a lower SOC receives a smaller charging current. This mechanism effectively promotes SOC balance among battery clusters during charging. Therefore, the phase-to-phase SOC balancing method proposed in this embodiment is applicable not only to the discharge process but also to the scenario of the grid charging the battery.

[0081] In addition, to achieve rapid interphase SOC balancing and prevent overmodulation, the interphase balance coefficient needs to be adjusted appropriately according to the actual operating conditions. K 1. However, the following conditions must be met:

[0082] (7)

[0083] in, express j The modulation signal after phase injection of zero-sequence voltage, Indicates the output of the power control loop. j The phase modulation signal, This indicates the number of H-bridge submodules contained in each phase of a cascaded energy storage system. This indicates the voltage of the DC-side battery cluster of the H-bridge submodule.

[0084] when With any v i When the directions are consistent, the result is K 1. Ensure and v i Arbitrary phase differences can exist without causing overmodulation. Therefore, K The range of values ​​for 1 is:

[0085] (8)

[0086] Among them, V m Here, S represents the grid voltage amplitude, and S indicates the degree of phase-to-phase SOC imbalance. S m Let S be the amplitude.

[0087] This embodiment achieves rapid interphase SOC convergence under different operating conditions by selecting the optimal interphase equalization coefficient within the modulation constraint range.

[0088] Figure 3 Showing K 1 with V m and S m The changing trend. The degree of phase imbalance can be obtained, which significantly affects the maximum achievable value. K 1max To achieve rapid phase equilibrium, K 1 should be as close as possible K 1max However, in practical applications, a certain modulation margin needs to be reserved to cope with sudden events such as grid disturbances and power fluctuations.

[0089] S104: Combines the zero-sequence voltage with the three-phase modulation signal output from the power control loop. u j The signals are superimposed and a carrier phase-shift modulation method is used to generate the PWM control signal for each switching device.

[0090] Figure 4The overall control strategy of the cascaded energy storage system is demonstrated, including: a power control loop, an intra-phase SOC equalization control loop, and an inter-phase SOC equalization control loop. The power control loop is based on a reference active power... P reactive power Q Grid voltage v gi and current feedback i j Output three-phase modulated signal u j The intra-phase SOC equalization control loop is based on the SOC value of each battery cluster. SOC jk Output phase equalization compensation signal u jnk To achieve consistency in the State of Charge (SOC) of each battery cluster within the same phase; the proposed inter-phase SOC equalization control loop is based on the inter-phase SOC difference and the angle of the rotating coordinate system. ωt and dq axis current i d , i q Output phase equalization signal u 0, used to regulate energy distribution between different phases. Power control loop output signal. u j After being superimposed with the intra-phase equalization signal, it is then combined with the inter-phase equalization signal. u The zeros are superimposed to form the final modulation signals for each phase. u mjk The modulation signal, after being modulated by carrier phase-shift PWM, generates the switching signals required by the H-bridge power devices in the submodule. S jk This enables precise control of cascaded energy storage systems. Through the aforementioned control strategies, it is possible to achieve rapid power response while effectively coordinating SOC balance within and between phases, thereby improving the operational stability and lifespan of the energy storage system.

[0091] Figure 5 Under a 10kV grid environment, the output active power is 4MW and reactive power is 3MW. The number of submodules per phase is N=13, the rated voltage of the battery cluster is 768V, 5Ah, and the grid-side inductance is... L fSimulation results using the fast phase-to-phase equalization method of this embodiment are presented under an 8mH environment with initial SOCs of 70%, 80%, and 90% for phases A, B, and C, respectively. The initial state is discharge, switching to charging at 20s, and then back to discharge at 30s. Throughout the process, the average SOC of each phase converges linearly, and phase-to-phase equalization is achieved at 42s. This demonstrates that the method proposed in this embodiment has a significant effect on achieving fast phase-to-phase SOC equalization of cascaded energy storage battery clusters.

[0092] This embodiment employs a power balancing method, using the converter output current phasor as a reference, to synthesize the ideal zero-sequence voltage required for rapid phase-to-phase balancing. This enables SOC balancing between cascaded energy storage battery clusters in scenarios with reactive power output. Simultaneously, considering the hard constraint of modulation saturation limits, limiting balancing coefficients under different balancing degrees and grid voltages are obtained to achieve rapid SOC balancing. Based on this embodiment, the method can effectively improve the energy utilization rate of the energy storage system, enhancing its economic efficiency; at the same time, it can effectively prevent battery cluster overcharging and over-discharging, improving the safety of the energy storage system.

[0093] Example 2

[0094] In one or more embodiments, a cascaded energy storage fast phase-to-phase equalization control system is disclosed, comprising:

[0095] The data acquisition module is configured to acquire the SOC information, output voltage and current information of each phase battery cluster in the cascaded energy storage system.

[0096] The power deviation construction module is configured to output a three-phase modulated signal to the power control loop. u j Inject a zero-sequence voltage with a set amplitude and phase. u 0. Construct an interphase power deviation model; using the measured three-phase output current as input, obtain the zero-sequence voltage that achieves interphase output power balance based on the output current phasor;

[0097] The equalization conversion module is configured to establish the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replace the equalization object with the average SOC of each battery cluster, and obtain the zero-sequence voltage required to achieve inter-phase SOC balance based on the output current phasor.

[0098] The switching control module is configured to modulate the zero-sequence voltage with a three-phase modulation signal output from the power control loop. u j The signals are superimposed and a carrier phase-shift modulation method is used to generate the PWM control signal for each switching device.

[0099] It should be noted that the specific implementation methods of the above modules have been described in Example 1, and will not be detailed here.

[0100] Example 3

[0101] In one or more embodiments, a terminal device is disclosed, comprising a processor and a memory, wherein the processor is used to implement instructions; and the memory is used to store multiple instructions adapted to be loaded by the processor and executed by the processor to perform the cascaded energy storage fast phase-to-phase equalization control method described in Embodiment 1.

[0102] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0103] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0104] In the implementation process, each step of the above method can be completed by the integrated logic circuits in the processor hardware or by software instructions.

[0105] Example 4

[0106] In one or more embodiments, a computer-readable storage medium is disclosed, wherein a plurality of instructions are stored, the instructions being adapted to be loaded by a processor of a terminal device and executed by the cascaded energy storage fast phase-to-phase equalization control method described in Embodiment 1.

[0107] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for controlling a cascade energy storage fast inter-area power oscillation equalizer, characterized in that, The method comprises the following steps: Obtaining the SOC information, output voltage and current information of each phase battery cluster of the cascaded energy storage system; Injecting a zero sequence voltage of a set amplitude and phase into a three-phase modulation signal output to a power control loop u 0, constructing an inter-phase power deviation model; taking the measured three-phase output current as input, obtaining a zero sequence voltage for realizing inter-phase output power balance based on the output current phasor, specifically: ； wherein, denotes the given apparent power, denotes the total reference output power of the system, denotes the reference output power of the jth phase, , , are the instantaneous currents of the three-phase output of the cascaded energy storage system ABC, respectively, is the root mean square value of the output current of the cascaded energy storage system.​ Establishing the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replacing the balancing object with the average SOC of each phase battery cluster, and obtaining the zero sequence voltage required for realizing the inter-phase SOC balance based on the output current phasor; Superimposing the zero sequence voltage and the three-phase modulation signal output by the power control loop, and generating the PWM control signal of each switching device by using the carrier phase-shifted modulation method.

2. The method of claim 1, wherein the method is characterized by, The inter-phase power deviation model is specifically: ； wherein the output power added for each phase, denotes the total reference output power of the system, denotes the reference output power of the jth phase, I g is the root mean square value of the output current of the cascaded energy storage system, denotes the zero sequence voltage u 0 the amplitude of the projection of the three-phase output current in the direction of the zero sequence voltage.

3. The cascade-type energy storage fast inter-area equalization control method of claim 1, wherein, Establishing the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, specifically: ； wherein, represents the total reference output power of the system, represents the reference output power of the jth phase, SOC avj represents the average SOC value of the jth phase battery cluster, SOC T represents the sum of all SOC avj .​ 4. The cascade-type energy storage fast inter-area equalization control method of claim 1, wherein, Replacing the balancing object with the average SOC of each phase battery cluster, and obtaining the zero sequence voltage required for realizing the inter-phase SOC balance based on the output current phasor, specifically: ； wherein, K 1 is the inter-phase balance coefficient, which determines the balance speed; denotes the given apparent power, denotes the total reference output power of the system, I g is the root mean square value of the output current of the cascaded energy storage system; SOC avj denotes the average SOC value of the jth phase battery cluster, SOC T represents the sum of all SOC avj the sum of all 5. The cascade-type energy storage fast inter-area equalization control method of claim 4, wherein, The inter-phase balance coefficient K 1. According to the actual operating conditions adjustment, in order to realize the fast inter-phase SOC balance and prevent over-modulation, the zero sequence voltage needs to meet the following conditions: ； wherein, represents j the modulation signal after injection of the phase zero sequence voltage, represents the power control loop output j the modulation signal of the phase, represents the number of H-bridge sub-modules contained in each phase of the cascaded energy storage system, represents the voltage of the battery cluster at the DC side of the H-bridge sub-module.

6. The cascade-type energy storage fast inter-area equalization control method of claim 4, wherein, the inter-phase balance coefficient K 1 is in the range of values: ； wherein, is the grid voltage amplitude, S represents the total inter-phase SOC imbalance degree of the cascaded energy storage system, is the amplitude of S.

7. A cascade energy storage fast inter-area equalization control system, characterized in that, The method comprises the following steps: A data acquisition module configured to obtain the SOC information, output voltage and current information of each phase battery cluster of the cascaded energy storage system; a power deviation building module configured to inject a zero sequence voltage with a set amplitude and phase into a three-phase modulation signal output to a power control loop u 0, build a phase-to-phase power deviation model; obtain a zero sequence voltage for achieving phase-to-phase output power balance based on an output current phasor with the measured three-phase output current as input, specifically: ； wherein, denotes the given apparent power, denotes the total reference output power of the system, denotes the reference output power of the jth phase, are the instantaneous currents of the three-phase output of the cascaded energy storage system ABC, respectively, is the root mean square value of the output current of the cascaded energy storage system.​​​ An equalization conversion module configured to establish the relationship between the reference output power of each phase and the average SOC of the corresponding battery cluster, replace the balancing object with the average SOC of each phase battery cluster, and obtain the zero sequence voltage required for realizing the inter-phase SOC balance based on the output current phasor; a switch control module configured to combine the zero sequence voltage with a three-phase modulation signal output by a power control loop u j Superposition is performed, and a carrier phase-shift modulation method is used to generate a PWM control signal for each switching device.

8. A terminal device comprising a processor and a memory, the processor configured to implement instructions; the memory configured to store a plurality of instructions, the terminal device characterized by, The instructions are adapted to be loaded and executed by the processor to perform the cascaded energy storage fast inter-phase equalization control method of any one of claims 1-6.

9. A computer-readable storage medium having stored therein a plurality of instructions, wherein the instructions, when executed by a processor, cause the processor to perform operations comprising: The instructions are adapted to be loaded and executed by the processor of the terminal device to perform the cascaded energy storage fast inter-phase equalization control method of any one of claims 1-6.

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