A series energy storage circuit in grid-connected mode and its equalization control method

Abstract

This invention relates to the field of energy storage technology and provides a series energy storage circuit and its equalization control method in grid-connected mode. The circuit includes multiple series energy storage system modules, which are connected in series. One end of each series energy storage system module is grounded, and the other end is connected to the AC power grid. Each subsystem communicates point-to-point to acquire global information. SoC equalization can be achieved using only the SoC information of its neighbors, enabling synchronization in grid-connected mode and resolving the SoC imbalance problem in series energy storage systems. This achieves SoC equalization and effectively prevents overcharging and over-discharging of modules during charging and discharging operations, thus avoiding degradation of battery life. Due to the long timescale of SoC control, the requirements for distributed communication are low, and good control performance can be maintained even under communication latency and single-link communication failures.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, and specifically relates to a series energy storage circuit and its equalization control method in grid-connected mode. Background Technology

[0002] With the development of clean and low-carbon goals, the proportion of new energy installations such as photovoltaic and wind power in the power generation side is constantly increasing. As the link between power generation and power consumption in the power system, the power grid is becoming weaker and weaker due to the increasing proportion of non-storable and uncontrollable new energy installations.

[0003] When discussing energy storage unit degradation, the first thing that comes to mind is usually battery failure. However, the problem may actually lie in the "concentrated operation" mode. In traditional energy storage solutions, battery modules are directly connected in parallel, and the voltage is forced to balance. During charging, if one battery cell is fully charged, all the parallel battery clusters must stop charging; similarly, during discharging, if one battery cell is completely discharged, all the parallel battery clusters must stop discharging. The overall lifespan of the system depends on the battery with the shortest lifespan. While batteries are highly consistent at the factory, it is difficult to guarantee consistency in real-world applications, which can lead to exponential capacity degradation of the system.

[0004] Synchronization of series inverters is a core issue in their control. Traditional control methods typically rely on a central controller and a global communication network to obtain all necessary information, including frequency, voltage phase angle, and other essential data. As series inverter systems scale up, high-bandwidth communication increases costs. Furthermore, communication delays and failures negatively impact system reliability. State of Charge (SoC) is another crucial metric for Series-type Energy Storage Systems (SESS). In SESS, each module has a different initial SoC value and output power, leading to SoC imbalance and consequently overcharging and over-discharging issues. Clearly, SoC imbalance reduces SESS lifespan. Existing control schemes rely on centralized control, placing high demands on communication; therefore, a low-bandwidth-dependent SoC balancing control scheme is urgently needed. Summary of the Invention

[0005] To address the aforementioned issues, this invention discloses a series energy storage circuit in grid-connected mode. The circuit includes multiple series energy storage system modules, which are connected in series with each other. One end of each of the multiple series energy storage system modules is grounded, and the other end is connected to the AC power grid. The series energy storage system module includes an energy storage battery, a balance controller, an inverter module, an inductor, and a capacitor; The energy storage battery and the equalization controller are connected in parallel with the inverter module. The capacitor is connected in parallel with the inverter module. An inductor is electrically connected between the inverter module and the capacitor. The equalization controller is used to execute the equalization control model to equalize and adjust the charge state of the energy storage batteries in multiple series-connected energy storage system modules.

[0006] Furthermore, the inverter module includes four switching diode units, two switching diode units form a switching diode group, the two switching diode groups are connected in parallel in the same direction, and the two switching diode units in each group are connected in series.

[0007] Furthermore, the switching transistor-diode unit includes a switching transistor and a diode, which are connected in reverse parallel; the collector of the switching transistor is connected to the anode of the diode, and the emitter of the switching transistor is connected to the cathode of the diode.

[0008] Furthermore, between the two interconnected switching diode units, the emitter of the switching transistor in one switching diode unit is connected to the collector of the switching transistor in the other switching diode unit.

[0009] Furthermore, one end of the inductor is connected between two switching diode units in a switching diode group; the other end of the inductor in the first series-connected energy storage system module is connected to the AC grid side, and the other end of the inductor in the remaining series-connected energy storage system modules is connected between two switching diode units in another switching diode group in an adjacent series-connected energy storage system module; and the middle of the two switching diode units in another switching diode group in the last series-connected energy storage system module is grounded.

[0010] Furthermore, the inverter module is connected in parallel with a capacitor, one end of which is connected to the other end of an inductor, and the other end of which is connected between two switching diode units in another switching diode group.

[0011] Furthermore, the circuit also includes a line impedance, one end of which is connected to the other end of the multiple series-connected energy storage system modules, and the other end of which is connected to the busbar on the AC grid side.

[0012] Furthermore, the circuit also includes a load and a transfer switch disposed on the AC power grid side; one end of the transfer switch is connected to the busbar on the AC power grid side, and the other end is connected to the AC power source; one end of the load is connected to the busbar on the AC power grid side, and the other end is grounded.

[0013] Furthermore, the equilibrium control model is specifically as follows:

[0014] in, The reference angular frequency for each series energy storage system module; The desired balanced output angular frequency for each series energy storage system module; and Let represent the reference active power and actual output power of the i-th series energy storage system module, respectively. For the first series energy storage system The state of charge (SOC) value of the energy storage batteries in a series-connected energy storage system module. Let be the average state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. and Let represent the reference voltage and the desired balanced output voltage of the i-th series energy storage system module, respectively; m is the active power-frequency proportional control coefficient of the i-th series energy storage system module; k is the SoC balanced control coefficient of the i-th series energy storage system module; and N is the number of series energy storage system modules in the series energy storage system.

[0015] Furthermore, the aforementioned The algorithm is as follows:

[0016] in, For the first series energy storage system The state of charge (SOC) values ​​of the energy storage batteries in a series-connected energy storage system module; and These are the average state of charge (SOC) values ​​of the energy storage batteries in the i-th and j-th series energy storage system modules, respectively; N i a represents the set of adjacent nodes i; ij Let a represent the communication weight of node i that receives data from node j, where if there is an edge connecting node i to node j, then a ij =1, where if there is no edge connecting node i to node j, then a ij =0.

[0017] Furthermore, the equalization controllers in the multiple series-connected energy storage system modules communicate with each other using a distributed communication topology to transmit angular frequency and estimated SoC values.

[0018] On another aspect, the present invention also discloses a balancing control method for a series energy storage circuit in grid-connected mode, the balancing control method comprising: Collect the inductor current, real-time output current, real-time output voltage, and SoC value of the energy storage battery in the series energy storage system module in the series energy storage circuit. Based on the collected real-time output voltage, real-time output current, and energy storage battery SoC value, the actual output power, local SoC value, and average SoC value of the series energy storage system module can be obtained. The equalization controller obtains the desired equalization output angular frequency of the series energy storage system module based on the actual output power, local SoC value, average SoC value, reference active power of the series energy storage system module, and reference angular frequency of the series energy storage system module. By combining the desired balanced output angular frequency and desired balanced output voltage of the series energy storage system module, as well as the real-time output voltage and inductor current, the balanced control pulse signal of the series energy storage system module is obtained, and the balanced control pulse signal is used to control the operation of the series energy storage system module.

[0019] Furthermore, the desired balanced output angular frequency and desired balanced output voltage are calculated using a series energy storage system equalization control model, which is as follows:

[0020] in, The reference angular frequency for each series energy storage system module; The desired balanced output angular frequency for each series energy storage system module; and Let represent the reference active power and actual output power of the i-th series energy storage system module, respectively. For the first series energy storage system The state of charge (SOC) value of the energy storage batteries in a series-connected energy storage system module. Let be the average state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. and Let represent the reference voltage and the desired balanced output voltage of the i-th series energy storage system module, respectively; m is the active power-frequency proportional control coefficient of the i-th series energy storage system module; k is the SoC balanced control coefficient of the i-th series energy storage system module; and N is the number of series energy storage system modules in the series energy storage system.

[0021] Furthermore, the algorithm for the average SoC value is as follows:

[0022] in, For the first series energy storage system The state of charge (SOC) values ​​of the energy storage batteries in a series-connected energy storage system module; and These are the average state of charge (SOC) values ​​of the energy storage batteries in the i-th and j-th series energy storage system modules, respectively; Ni a represents the set of adjacent nodes i; ij Let a represent the communication weight of node i that receives data from node j, where if there is an edge connecting node i to node j, then a ij =1, where if there is no edge connecting node i to node j, then a ij =0.

[0023] Compared with the prior art, the present invention has the following beneficial effects: Distributed communication is a decentralized communication method that eliminates the need for a centralized controller. Instead, each subsystem acquires global information through point-to-point communication, requiring only neighboring SoC information to achieve SoC balancing. It enables synchronization in grid-connected mode and resolves the SoC imbalance problem in series energy storage systems, effectively preventing overcharging and over-discharging of modules during charging and discharging operations, thus avoiding battery life degradation. Due to the longer timescale of SoC regulation, the requirements for distributed communication are lower, maintaining good control performance even under communication latency and single-link communication failures. Compared to centralized control schemes, this method, employing distributed communication, improves system reliability.

[0024] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the series energy storage circuit structure in the grid-connected mode of the present invention is shown; Figure 2 The data transmission flowchart of the series energy storage circuit equalization control in grid-connected mode of the present invention is shown; Figure 3 A flowchart of the present invention for implementing a series energy storage circuit equalization control method is shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Figure 1 A schematic diagram of the series energy storage circuit structure in grid-connected mode of the present invention is shown. The circuit includes multiple series energy storage system modules, which are connected in series with each other. One end of each series energy storage system module is grounded, and the other end is connected to the AC grid side. Each series energy storage system module includes an energy storage battery, an equalization controller, an inverter module, an inductor, and a capacitor. The energy storage battery and the equalization controller are connected in parallel with the inverter module, and the capacitor is connected in parallel with the inverter module. An inductor is electrically connected between the inverter module and the capacitor. The equalization controller is used to execute an equalization control model to equalize and adjust the charge state of the energy storage batteries in the multiple series energy storage system modules.

[0029] exist Figure 1 The inverter module includes four switching diode units. Two switching diode units form a switching diode group, and the two switching diode groups are connected in parallel with each other in the same direction. Each switching diode group consists of two switching diode units connected in series. Each switching diode unit includes a switching transistor and a diode, which are connected in parallel with each other in opposite directions. The collector of the switching transistor is connected to the anode of the diode, and the emitter of the switching transistor is connected to the cathode of the diode. Between two series-connected switching diode units, the emitter of the switching transistor in one unit is connected to the collector of the switching transistor in the other unit.

[0030] One end of the inductor is connected between two diode units in a diode group. The other end of the inductor in the first series-connected energy storage system module is connected to the AC grid side. The other ends of the inductors in the remaining series-connected energy storage system modules are connected between two diode units in another diode group in an adjacent series-connected energy storage system module. The two diode units in another diode group in the last series-connected energy storage system module are grounded in the middle. The inverter module is connected in parallel with a capacitor. One end of the capacitor is connected to the other end of the inductor, and the other end of the capacitor is connected between two diode units in another diode group.

[0031] In addition, the circuit includes a line impedance, one end of which is connected to the other end of multiple series-connected energy storage system modules, and the other end of which is connected to the busbar on the AC grid side. The circuit also includes a load and a transfer switch installed on the AC grid side; one end of the transfer switch is connected to the busbar on the AC grid side, and the other end is connected to the AC power source; one end of the load is connected to the busbar on the AC grid side, and the other end is grounded.

[0032] exist Figure 1 middle, For line impedance, For load, and These represent the output voltages of series energy storage system module 1 and series energy storage system module N, respectively. The voltage on the AC grid side is represented by PCC (Point of Common Coupling) and STS (Static Transfer Switch), which respectively represent the grid connection point and the grid-off switching point.

[0033] It should be noted that the equalization controllers in the multiple series energy storage system modules use a distributed communication topology to transmit and communicate angular frequency and estimated SoC values.

[0034] exist Figure 2 In the middle, the left side of the figure shows the framework of a series energy storage system ( Figure 1 (Simplified version) Series energy storage systems can effectively improve voltage and power levels. A series energy storage system includes the AC grid side, line impedance, and multiple modules (referring to modules in the series energy storage system). The balancing control process of one module is explained in detail, such as... Figure 2 On the right side, the data acquisition unit first obtains the SoC value of the energy storage battery of the series energy storage system module (the SoC value obtained for the first time is the initial SoC value) and the current i of the series inductor of the i-th inverter. L The output current i of the series energy storage system module o and output voltage u o Then, the power calculation unit calculates the actual output power P of the series energy storage system module. i Then, the local SoC estimation subunit calculates the local SoC value, and the average SoC estimator calculates the average SoC value. The obtained data is then sent to the SoC equalization control unit, which executes the SoC equalization control model. Simultaneously, the SoC equalization control unit obtains the reference active power P of the i-th series energy storage system module. The reference angular frequency ω of each series energy storage system module. The expected equalization output angular frequency ω of each series energy storage system module was calculated. i For the desired equalized output angular frequency ω i Conduct the points-based process ( Figure 2 The calculation of 1 / s (representing the integral element) is combined with the expected balanced output voltage V of the series energy storage system module. i After processing by a voltage and current dual closed-loop control unit and PWM conversion, a pulse signal is obtained to control the series energy storage system modules. This pulse signal is then sent back to the series energy storage system modules to adjust them, ensuring that the state of charge of the energy storage batteries in each module of the series energy storage system reaches equilibrium in grid-connected operation. Additionally, the equilibrium control system includes a communication unit used to transmit the angular frequency and estimated SoC value between the series energy storage system modules using a distributed communication topology.

[0035] Figure 3 The flowchart of the present invention for implementing a series energy storage circuit equalization control method is shown, the method comprising the following steps: First, the real-time output voltage, real-time output current, and SoC value of the energy storage battery of the series energy storage system module are collected. Based on the collected real-time output voltage, real-time output current, and energy storage battery SoC value, the actual output power, local SoC value, and average SoC value of the series energy storage system module can be obtained. The desired balanced output angular frequency of the series energy storage system module is obtained based on the actual output power, local SoC value, average SoC value, reference active power of the series energy storage system module, and reference angular frequency of the series energy storage system module. By combining the desired balanced output angular frequency and desired balanced output voltage of the series energy storage system module, as well as the real-time output voltage and the current on the series inductor within the series energy storage system module, the balanced control pulse signal of the series energy storage system module is obtained.

[0036] Specifically, the output voltage and current of each module in the series energy storage system are collected in real time, the actual output power of each module is calculated, and a balanced control model of the series energy storage system is constructed. Among these, the first... The equalization control model for a series energy storage system module is as follows: (1) in, The reference angular frequency for each series energy storage system module; The desired balanced output angular frequency for each series energy storage system module. and Let represent the reference active power and actual output power of the i-th series energy storage system module, respectively. For the first series energy storage system The state of charge (SOC) value of the energy storage batteries in a series-connected energy storage system module. Let be the average state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. and Let represent the reference voltage and the desired balanced output voltage of the i-th series energy storage system module, respectively; m is the active power-frequency proportional control coefficient of the i-th series energy storage system module; k is the SoC balanced control coefficient of the i-th series energy storage system module; and N is the number of series energy storage system modules in the series energy storage system.

[0037] The average SoC value estimated by neighbors is obtained using a distributed communication topology, and then an algorithm for estimating the average SoC value is designed based on a dynamic consensus control protocol. (2) in, For the first series energy storage system The state of charge (SOC) values ​​of the energy storage batteries in a series-connected energy storage system module; and These are the average state of charge (SOC) values ​​of the energy storage batteries in the i-th and j-th series energy storage system modules, respectively; N i a represents the set of adjacent nodes i; ij Let a represent the communication weight of node i that receives data from node j, where if there is an edge connecting node i to node j, then a ij =1, where if there is no edge connecting node i to node j, then a ij =0.

[0038] The principle of the SoC equalization control algorithm constructed in this invention will be further explained below: Representing all average SoC values ​​of SESS dynamically in matrix form, we can obtain: (3) Where I is the unit diagonal matrix, H is the average SoC estimator transfer function, L is the Laplacian matrix carrying communication graph information, and s is the Laplacian operator. The matrix formed by the estimated SoC values. A matrix composed of actual SoC values.

[0039] If the Laplace matrix L is balanced, we can obtain: (4) in, , ...... The values ​​represent the average state of charge (SOC) values ​​of the energy storage batteries in the first to Nth series energy storage system modules, respectively. For the first series energy storage system The state of charge (SOC) value of the energy storage batteries in a series energy storage system module; N is the number of energy storage batteries in the series energy storage system module.

[0040] SoC balancing can be achieved by utilizing the output power of the i-th series energy storage system module and the j-th series energy storage system module. When At that time, P i Bigger, and P j Lower. In charging mode, the power absorbed by the series energy storage system module with the larger SoC value is less than that absorbed by the series energy storage system module with the smaller SoC value; in discharging mode, the output power of the series energy storage system module with the larger SoC value is greater than that of the series energy storage system module with the smaller SoC value; in steady state, the SoC values ​​of the series energy storage system modules in SESS tend to be consistent.

[0041] Distributed communication is a decentralized communication method that eliminates the need for a centralized controller. Instead, each subsystem acquires global information through point-to-point communication, requiring only neighboring SoC information to achieve SoC balancing. It enables synchronization in grid-connected mode and resolves the SoC imbalance problem in series energy storage systems, effectively preventing overcharging and over-discharging of modules during charging and discharging operations, thus avoiding battery life degradation. Due to the longer timescale of SoC regulation, the requirements for distributed communication are lower, maintaining good control performance even under communication latency and single-link communication failures. Compared to centralized control schemes, this method, employing distributed communication, improves system reliability.

[0042] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A series energy storage circuit in grid-connected mode, characterized in that, The circuit includes multiple series energy storage system modules, which are connected in series with each other. One end of each series energy storage system module is grounded, and the other end is connected to the AC power grid. The series energy storage system module includes an energy storage battery, a balance controller, an inverter module, an inductor, and a capacitor; The energy storage battery and the equalization controller are connected in parallel with the inverter module. The capacitor is connected in parallel with the inverter module. An inductor is electrically connected between the inverter module and the capacitor. The equalization controller is used to execute the equalization control model to equalize and adjust the charge state of the energy storage batteries in multiple series-connected energy storage system modules. The equilibrium control model is specifically as follows: ； in, The reference angular frequency for each series energy storage system module; The desired equalized output angular frequency for each series energy storage system module; and Let represent the reference active power and the actual output power of the i-th series energy storage system module, respectively. Let be the state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. Let be the average state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. and Let represent the reference voltage and the desired balanced output voltage of the i-th series energy storage system module, respectively; m is the active power-frequency proportional control coefficient of the i-th series energy storage system module; k is the SoC balanced control coefficient of the i-th series energy storage system module; and N is the number of series energy storage system modules.

2. The series energy storage circuit in grid-connected mode according to claim 1, characterized in that, The inverter module includes four switching diode units. Two switching diode units form a switching diode group. The two switching diode groups are connected in parallel with each other in the same direction. The two switching diode units in each group are connected in series.

3. The series energy storage circuit in grid-connected mode according to claim 2, characterized in that, The switching transistor-diode unit includes a switching transistor and a diode, which are connected in parallel in reverse. The collector of the switching transistor is connected to the anode of the diode, and the emitter of the switching transistor is connected to the cathode of the diode.

4. The series energy storage circuit in grid-connected mode according to claim 3, characterized in that, Between two interconnected switching diode units, the emitter of the switching transistor in one switching diode unit is connected to the collector of the switching transistor in the other switching diode unit.

5. The series energy storage circuit in grid-connected mode according to claim 2, characterized in that, One end of the inductor is connected between two switching diode units in a switching diode group; the other end of the inductor in the first series-connected energy storage system module is connected to the AC grid side, and the other end of the inductor in the remaining series-connected energy storage system modules is connected between two switching diode units in another switching diode group in an adjacent series-connected energy storage system module; the middle of the two switching diode units in another switching diode group in the last series-connected energy storage system module is grounded.

6. The series energy storage circuit in grid-connected mode according to claim 5, characterized in that, The inverter module is connected in parallel with a capacitor, one end of which is connected to the other end of an inductor, and the other end of which is connected between two switching diode units in another switching diode group.

7. The series energy storage circuit in grid-connected mode according to claim 1, characterized in that, The circuit also includes a line impedance, one end of which is connected to the other end of a series of multiple series-connected energy storage system modules, and the other end of which is connected to the busbar on the AC grid side.

8. The series energy storage circuit in grid-connected mode according to any one of claims 1-7, characterized in that, The circuit also includes a load and a transfer switch disposed on the AC power grid side; one end of the transfer switch is connected to the busbar on the AC power grid side, and the other end is connected to the AC power source; one end of the load is connected to the busbar on the AC power grid side, and the other end is grounded.

9. The series energy storage circuit in grid-connected mode according to claim 1, characterized in that, The The algorithm is as follows: in, For the first The state of charge (SOC) values ​​of the energy storage batteries in a series-connected energy storage system module; and These are the average state of charge values ​​of the energy storage batteries in the i-th and j-th series energy storage system modules, respectively; N i a represents the set of adjacent nodes i; ij Let a represent the communication weight of node i that receives data from node j, where if there is an edge connecting node i to node j, then a ij =1, where if there is no edge connecting node i to node j, then a ij =0.

10. The series energy storage circuit in grid-connected mode according to claim 1, characterized in that, The equalization controllers in the multiple series-connected energy storage system modules use a distributed communication topology to monitor angular frequency and... The transmission and communication.

11. A method for equalization control of a series energy storage circuit in grid-connected mode as described in any one of claims 1-10, characterized in that, The equilibrium control method includes: Collect the inductor current, real-time output current, real-time output voltage, and SoC value of the energy storage battery in the series energy storage system module in the series energy storage circuit. Based on the collected real-time output voltage, real-time output current, and energy storage battery SoC value, the actual output power, local SoC value, and average SoC value of the series energy storage system module can be obtained. The equalization controller obtains the desired equalization output angular frequency of the series energy storage system module based on the actual output power, local SoC value, average SoC value, reference active power of the series energy storage system module, and reference angular frequency of the series energy storage system module. By combining the desired balanced output angular frequency and desired balanced output voltage of the series energy storage system module, as well as the real-time output voltage and inductor current, the balanced control pulse signal of the series energy storage system module is obtained, and the balanced control pulse signal is used to control the operation of the series energy storage system module. The desired balanced output angular frequency and desired balanced output voltage are calculated using a balanced control model. The balanced control model for the series energy storage system is as follows: ； in, The reference angular frequency for each series energy storage system module; The desired equalized output angular frequency for each series energy storage system module; and Let represent the reference active power and the actual output power of the i-th series energy storage system module, respectively. Let be the state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. Let be the average state of charge (SOC) value of the energy storage battery in the i-th series energy storage system module. and Let represent the reference voltage and the desired balanced output voltage of the i-th series energy storage system module, respectively; m is the active power-frequency proportional control coefficient of the i-th series energy storage system module; k is the SoC balanced control coefficient of the i-th series energy storage system module; and N is the number of series energy storage system modules.

12. The equalization control method for a series energy storage circuit in grid-connected mode according to claim 11, characterized in that, The The algorithm is as follows: in, For the first The state of charge (SOC) values ​​of the energy storage batteries in a series-connected energy storage system module; and These are the average state of charge values ​​of the energy storage batteries in the i-th and j-th series energy storage system modules, respectively; N i a represents the set of adjacent nodes i; ij Let a represent the communication weight of node i that receives data from node j, where if there is an edge connecting node i to node j, then a ij =1, where if there is no edge connecting node i to node j, then a ij =0.

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