Energy storage device voltage equalization control method and system

Abstract

The application discloses an energy storage device voltage equalization control method and system, wherein the method comprises the following steps: acquiring the instantaneous voltage values of a plurality of energy storage devices, and calculating the average voltage values of the plurality of energy storage devices; obtaining the adjustment values of the transmission power of each energy storage device according to the instantaneous voltage values and the average voltage values; and adjusting the transmission power of the energy storage device through a controller according to the adjustment values of the transmission power of the energy storage device, so as to realize the voltage equalization control of the plurality of energy storage devices. The adjustment values of the transmission power of each energy storage device are calculated by detecting the instantaneous voltage and the average voltage of each energy storage device, the parameters related to the transmission power are adjusted, and the voltage of each energy storage device is equalized by adjusting the transmission power.

Description

Technical Field

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

[0002] The energy storage device is connected to the DC distribution network via a DC / DC converter. The high-voltage side of the DC / DC converter is connected in series and directly connected to the DC bus of the DC distribution network. The low-voltage side is connected in parallel in groups, with each group connected to a separate energy storage device. Due to limitations in technology, there are differences between the groups of energy storage devices and between the DC / DC converters connected to the energy storage devices, resulting in voltage imbalances during the charging and discharging process of the energy storage devices.

[0003] When multiple energy storage devices are connected in parallel on the low-voltage side of a high-frequency isolation DC transformer, the voltage of each energy storage device becomes unbalanced due to differences in the parameters of the primary equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a voltage equalization control method and system for energy storage devices. By detecting the instantaneous voltage and average voltage of each energy storage device, the adjustment value of the transmission power of each energy storage device is calculated, and the parameters related to the transmission power are adjusted. By adjusting the transmission power, voltage equalization of each energy storage device is achieved.

[0005] To address the aforementioned technical problems, a first aspect of this invention provides a method for controlling the voltage equalization of an energy storage device, comprising the following steps:

[0006] Obtain the instantaneous voltage values ​​of several energy storage devices, and calculate the average voltage value of the several energy storage devices;

[0007] Based on the instantaneous voltage value and the average voltage value, the adjustment value of the transmission power of each energy storage device is obtained;

[0008] Referring to the adjustment value of the transmission power of the energy storage device, the transmission power of the energy storage device is adjusted by the controller to achieve voltage equalization control of the plurality of energy storage devices.

[0009] Further, adjusting the transmission power of the energy storage device via a controller, with reference to the adjustment value of the transmission power of the energy storage device, includes:

[0010] Determine whether the DC / DC converter connecting the energy storage device and the DC distribution network is in low-voltage side control mode;

[0011] If so, the controller adjusts the high-voltage side submodule capacitor voltage and low-voltage side current command to adjust the transmission power of the energy storage device.

[0012] If not, the controller adjusts the voltage of the high-voltage side submodule capacitor and the voltage of the low-voltage side submodule capacitor to adjust the transmission power of the energy storage device.

[0013] Further, the step of adjusting the transmission power of the energy storage device by means of the controller to adjust the high-voltage side submodule capacitor voltage and the low-voltage side current command includes:

[0014] Based on the adjustment value of the transmission power, calculate the adjustment values ​​of the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side;

[0015] Based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command, the controller adjusts the high-voltage side submodule capacitor voltage and the low-voltage side current command to adjust the transmission power of the energy storage device.

[0016] Furthermore, the adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side current command are respectively:

[0017]

[0018] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hi i is the capacitor voltage value of the high-voltage side submodule. refi Here, k is the low-voltage side current command value, and k is the proportionality coefficient.

[0019] Further, adjusting the transmission power of the energy storage device by means of the controller to adjust the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule includes:

[0020] Based on the adjustment value of the transmission power, calculate the adjustment values ​​of the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule;

[0021] Based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage, the controller adjusts the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage to adjust the transmission power of the energy storage device.

[0022] Furthermore, the adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage are respectively:

[0023]

[0024] Among them, u i u is the instantaneous voltage value of the energy storage device. avgu is the average voltage value of the energy storage device. hi u is the capacitor voltage value of the high-voltage side submodule. li The voltage value of the capacitor in the low-voltage side submodule is denoted by k, and k is a proportionality coefficient.

[0025] Accordingly, a second aspect of the present invention provides a voltage equalization control system for an energy storage device, comprising:

[0026] The detection module is used to acquire the instantaneous voltage values ​​of several energy storage devices and calculate the average voltage value of the several energy storage devices.

[0027] A calculation module is used to obtain an adjustment value for the transmission power of each energy storage device based on the instantaneous voltage value and the average voltage value.

[0028] The control module is used to adjust the transmission power of the energy storage device by referring to the adjustment value of the transmission power of the energy storage device, so as to realize the voltage equalization control of the plurality of energy storage devices.

[0029] Furthermore, the control module includes:

[0030] The judgment unit is used to determine whether the DC / DC converter connecting the energy storage device and the DC distribution network is in low-voltage side control mode.

[0031] A control unit is used to adjust the high-voltage side submodule capacitor voltage and low-voltage side current command through the controller when the DC / DC is in low-voltage side control mode, so as to adjust the transmission power of the energy storage device.

[0032] The control unit is also used to adjust the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule through the controller when the DC / DC is in high-voltage side control mode.

[0033] Furthermore, the control unit includes:

[0034] The first calculation subunit is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command based on the adjustment value of the transmission power.

[0035] The first control subunit is used to adjust the voltage of the high-voltage side submodule capacitor and the low-voltage side current command through the controller according to the adjustment value of the high-voltage side submodule capacitor voltage and the low-voltage side current command, so as to adjust the transmission power of the energy storage device.

[0036] Furthermore, the adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side current command are respectively:

[0037]

[0038] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hi i is the capacitor voltage value of the high-voltage side submodule. refi Here, k is the low-voltage side current command value, and k is the proportionality coefficient.

[0039] Furthermore, the control unit includes:

[0040] The second calculation subunit is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage based on the adjustment value of the transmission power.

[0041] The second control subunit is used to adjust the voltage of the high-voltage side submodule and the voltage of the low-voltage side submodule by means of a controller, based on the adjustment values ​​of the voltage of the high-voltage side submodule and the voltage of the low-voltage side submodule, so as to adjust the transmission power of the energy storage device.

[0042] Furthermore, the adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage are respectively:

[0043]

[0044] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hi u is the capacitor voltage value of the high-voltage side submodule. li The voltage value of the capacitor in the low-voltage side submodule is denoted by k, and k is a proportionality coefficient.

[0045] The above-described technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0046] By detecting the instantaneous and average voltages of each energy storage device, the adjustment value of the transmission power of each energy storage device is calculated, and the parameters related to the transmission power are adjusted. By adjusting the transmission power, the voltage equalization of each energy storage device is achieved. Attached Figure Description

[0047] Figure 1 This is a circuit diagram of the energy storage device provided in an embodiment of the present invention;

[0048] Figure 2 This is a flowchart of the pressure equalization control method for an energy storage device provided in an embodiment of the present invention;

[0049] Figure 3This is a logic diagram of the pressure equalization control method for an energy storage device provided in an embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of the DC / DC low-voltage side control mode provided in an embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of the DC / DC high-voltage side control mode provided in an embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram of the DC / DC low-voltage side control mode provided in an embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of the energy storage pressure equalization control method in the low-pressure side control mode provided in an embodiment of the present invention;

[0054] Figure 8 This is a schematic diagram of the DC / DC high-voltage side control mode provided in an embodiment of the present invention;

[0055] Figure 9 This is a schematic diagram of the energy storage pressure equalization control method in the high-voltage side control mode provided in the embodiment of the present invention;

[0056] Figure 10 This is a block diagram of the voltage equalization control system module for the energy storage device provided in an embodiment of the present invention;

[0057] Figure 11 This is a block diagram of the control module provided in an embodiment of the present invention;

[0058] Figure 12 This is a block diagram of the control unit provided in an embodiment of the present invention.

[0059] Figure label:

[0060] 1. Detection module, 2. Calculation module, 3. Control module, 31. Judgment unit, 32. Control unit, 321. First calculation subunit, 322. First control subunit, 323. Second calculation subunit, 324. Second control subunit. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0062] Please refer to Figure 1 , Figure 2 and Figure 3The first aspect of this invention provides a method for controlling the equalization of voltage in an energy storage device, comprising the following steps:

[0063] S100: Obtain the instantaneous voltage values ​​of several energy storage devices and calculate the average voltage value of several energy storage devices.

[0064] The control objective is to ensure that the voltage of each group of energy storage devices is consistent. The transmission power adjustment is calculated in real time based on the difference between the voltage of each group of energy storage devices and the average value. Therefore, it is necessary to monitor the instantaneous voltage value of each energy storage device in real time and calculate the average voltage of each group of energy storage devices.

[0065] S200 obtains the adjustment value of the transmission power of each energy storage device based on the instantaneous voltage value and the average voltage value.

[0066] Based on the instantaneous and average voltage values ​​of each energy storage device, the adjustment amount of the transmission power of each energy storage device is calculated. The calculation method is as follows:

[0067]

[0068] In the formula, the proportionality coefficient k is related to the direction of power transmission. When power flows into the energy storage device (i.e., the energy storage device is in a charging state), if the voltage of a certain group of energy storage devices is high, it is desirable to reduce the charging power of that group of energy storage devices to make it charge more slowly and the voltage rise more slowly. Conversely, it is desirable to increase the charging power of that group of energy storage devices to make it charge more quickly and the voltage rise more quickly. Therefore, k is negative. When power flows out of the energy storage device (i.e., the energy storage device is in a discharging state), if the voltage of a certain group of energy storage devices is high, it is desirable to increase the discharging power of that group of energy storage devices to make it discharge more quickly and the voltage drop more quickly. Conversely, it is desirable to reduce the discharging power of that group of energy storage devices to make it discharge more slowly and the voltage drop more slowly. Therefore, k is positive. Moreover, the larger the absolute value of the proportionality coefficient k, the higher the voltage equalization efficiency.

[0069] S300, referring to the adjustment value of the transmission power of the energy storage device, adjusts the transmission power of the energy storage device through the controller to achieve voltage equalization control of several energy storage devices.

[0070] DC / DC converters connecting energy storage devices to DC distribution networks include two operating modes:

[0071] a. Low-voltage side control mode: The DC distribution network can provide a stable DC voltage for the DC / DC converter. In this case, the DC / DC converter needs to control the current on the low-voltage side to achieve charging and discharging control of the energy storage device. This is the low-voltage side control mode, such as... Figure 4 As shown.

[0072] b. High-voltage side control mode: When the DC distribution network cannot provide a stable DC voltage to the DC / DC converter, energy storage devices and the DC / DC converter are needed to jointly support and control the DC voltage of the DC distribution network. This is the high-voltage side control mode. Figure 5 As shown.

[0073] The control strategies differ between the two modes, therefore the voltage equalization control strategies also differ.

[0074] Further, in step S300, adjusting the transmission power of the energy storage device via the controller with reference to the adjustment value of the transmission power of the energy storage device includes:

[0075] S310, determine whether the DC / DC converter connecting the energy storage device and the DC distribution network is in low-voltage side control mode.

[0076] S320, if so, adjusts the high-voltage side submodule capacitor voltage and low-voltage side current command through the controller to adjust the transmission power of the energy storage device.

[0077] In low-voltage side control mode, a stable DC voltage is provided to the DC / DC converter by the DC distribution network. Therefore, the high-voltage side of the DC / DC converter adopts a dual closed-loop control method of submodule capacitor voltage outer loop - current inner loop, while the low-voltage side adopts a single current loop control method. Figure 6 As shown.

[0078] Furthermore, in step S320, adjusting the high-voltage side submodule capacitor voltage and low-voltage side current command via the controller to adjust the transmission power of the energy storage device includes:

[0079] S321a, based on the adjustment value of the transmission power, calculates the adjustment value of the high-voltage side submodule capacitor voltage and the low-voltage side current command.

[0080] S321b adjusts the voltage of the high-voltage side submodule capacitor and the current command of the low-voltage side through the controller to adjust the transmission power of the energy storage device based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command.

[0081] Specifically, in low-voltage side control mode, the high-voltage side submodule capacitor voltage and low-voltage side current are directly related to the transmission power. Therefore, the transmission power can be adjusted by synchronously adjusting the high-voltage side submodule capacitor voltage and low-voltage side current commands. Based on the calculation results of the transmission power adjustment amount according to this invention, the adjustment values ​​of the high-voltage side submodule capacitor voltage and low-voltage side current commands can be calculated as follows:

[0082]

[0083] Among them, u i u is the instantaneous voltage value of the energy storage device. avgu is the average voltage value of the energy storage device. hi i represents the capacitor voltage value of the high-voltage side submodule. refi is the low-voltage side current command value, and k is the proportional coefficient.

[0084] Based on the calculated adjustment amounts of the high-voltage side submodule capacitor voltage and low-voltage side current command values, corresponding adjustments and controls are made to the high-voltage side submodule capacitor voltage and low-voltage side current. This achieves corresponding adjustments to the transmission power and ultimately realizes voltage equalization control of the energy storage device. The principle of voltage equalization control of the energy storage device is as follows: Figure 7 As shown.

[0085] S330, if not, adjusts the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage via the controller to adjust the transmission power of the energy storage device.

[0086] In high-voltage side control mode, the DC distribution network loses its DC voltage control capability, requiring a DC / DC converter to take over DC voltage control. Therefore, the high-voltage side of the DC / DC converter adopts a dual closed-loop control method with an outer DC voltage loop and an inner current loop, while the low-voltage side adopts a dual closed-loop control method with an outer submodule capacitor voltage loop and an inner current loop. Figure 8 As shown.

[0087] Furthermore, in step S320, adjusting the voltage of the high-voltage side submodule capacitor and the low-voltage side submodule capacitor via the controller to adjust the transmission power of the energy storage device includes:

[0088] S322a, based on the adjustment value of the transmission power, calculate the adjustment values ​​of the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule.

[0089] S322b adjusts the voltage of the high-voltage side submodule capacitor and the low-voltage side submodule capacitor based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage through the controller, so as to adjust the transmission power of the energy storage device.

[0090] Specifically, in high-voltage side control mode, the capacitor voltages of the high-voltage side submodule and the low-voltage side submodule are directly related to the transmission power. Therefore, the transmission power can be adjusted by adjusting the capacitor voltages of the high-voltage side submodule and the low-voltage side submodule. Based on the calculation results of the transmission power adjustment amount according to this invention, the adjustment values ​​of the capacitor voltages of the high-voltage side submodule and the low-voltage side submodule can be calculated as follows:

[0091]

[0092] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hiThe voltage value of the capacitor in the high-voltage side submodule is u. li is the capacitor voltage value of the low-voltage side submodule, and k is the proportional coefficient.

[0093] Based on the calculated adjustment amounts of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage, corresponding adjustments and controls are made to the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage. This achieves corresponding adjustments to the transmission power and ultimately realizes voltage equalization control of the energy storage device. The principle of voltage equalization control of the energy storage device is as follows: Figure 9 As shown.

[0094] The above-mentioned voltage equalization control method for energy storage devices obtains the instantaneous and average voltage values ​​of each energy storage device, calculates the adjustment value of the transmission power, and then determines the control mode of the DC / DC converter. When the DC / DC converter is in the low-voltage side control mode, it adjusts the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side to adjust the transmission power value. When the DC / DC converter is in the high-voltage side control mode, it adjusts the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule to adjust the transmission power value, and finally achieves voltage equalization of each energy storage device.

[0095] Accordingly, please refer to Figure 10 A second aspect of the present invention provides a voltage equalization control system for an energy storage device, comprising:

[0096] Detection module 1 is used to acquire the instantaneous voltage values ​​of several energy storage devices and calculate the average voltage value of several energy storage devices.

[0097] Calculation module 2 is used to obtain the adjustment value of the transmission power of each energy storage device based on the instantaneous voltage value and the average voltage value;

[0098] Control module 3 is used to adjust the transmission power of the energy storage device by referring to the adjustment value of the transmission power of the energy storage device, so as to realize the voltage equalization control of several energy storage devices.

[0099] Further, please refer to Figure 11 The control module 3 includes:

[0100] Judgment unit 31 is used to determine whether the DC / DC connecting the energy storage device and the DC distribution network is in low-voltage side control mode;

[0101] Control unit 32 is used to adjust the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side through the controller when the DC / DC is in low-voltage side control mode.

[0102] The control unit 32 is also used to adjust the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule when the DC / DC is in high-voltage side control mode.

[0103] Further, please refer to Figure 12 The control unit 32 includes:

[0104] The first calculation subunit 321 is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command based on the adjustment value of the transmission power.

[0105] The first control subunit 322 is used to adjust the voltage of the high-voltage side submodule capacitor and the current command of the low-voltage side according to the adjustment value of the high-voltage side submodule capacitor voltage and the low-voltage side current command, so as to adjust the transmission power of the energy storage device.

[0106] Furthermore, the adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side current command are as follows:

[0107]

[0108] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hi i represents the capacitor voltage value of the high-voltage side submodule. refi is the low-voltage side current command value, and k is the proportional coefficient.

[0109] Furthermore, the control unit 32 includes:

[0110] The second calculation subunit 323 is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage based on the adjustment value of the transmission power.

[0111] The second control subunit 324 is used to adjust the voltage of the high-voltage side submodule capacitor and the low-voltage side submodule capacitor by means of the controller based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage, so as to adjust the transmission power of the energy storage device.

[0112] Furthermore, the adjustment values ​​for the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule are as follows:

[0113]

[0114] Among them, u i u is the instantaneous voltage value of the energy storage device. avg u is the average voltage value of the energy storage device. hi The voltage value of the capacitor in the high-voltage side submodule is u. li is the capacitor voltage value of the low-voltage side submodule, and k is the proportional coefficient.

[0115] The aforementioned energy storage device voltage equalization control system obtains the instantaneous and average voltage values ​​of each energy storage device, calculates the adjustment value of the transmission power, and then determines the control mode of the DC / DC converter. When the DC / DC converter is in the low-voltage side control mode, it adjusts the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side to adjust the transmission power value. When the DC / DC converter is in the high-voltage side control mode, it adjusts the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule to adjust the transmission power value, ultimately achieving voltage equalization of each energy storage device.

[0116] This invention aims to protect a voltage equalization control method and system for energy storage devices. The method includes the following steps: acquiring the instantaneous voltage values ​​of several energy storage devices; calculating the average voltage value of the several energy storage devices; obtaining an adjustment value for the transmission power of each energy storage device based on the instantaneous voltage value and the average voltage value; and adjusting the transmission power of the energy storage devices through a controller with reference to the adjustment value of the transmission power of the energy storage devices, so as to achieve voltage equalization control of several energy storage devices. The above technical solution has the following effects:

[0117] By detecting the instantaneous and average voltages of each energy storage device, the adjustment value of the transmission power of each energy storage device is calculated, and the parameters related to the transmission power are adjusted. By adjusting the transmission power, the voltage equalization of each energy storage device is achieved.

[0118] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for voltage equalization control in an energy storage device, characterized in that, Includes the following steps: Obtain the instantaneous voltage values ​​of several energy storage devices, and calculate the average voltage value of the several energy storage devices; Based on the instantaneous voltage value and the average voltage value, the adjustment value of the transmission power of each energy storage device is obtained; Referring to the adjustment value of the transmission power of the energy storage device, the transmission power of the energy storage device is adjusted by the controller to achieve voltage equalization control of the plurality of energy storage devices; the DC / DC connecting the energy storage device and the DC distribution network has two operating modes: low-voltage side control mode and high-voltage side control mode; in the low-voltage side control mode, the DC distribution network provides a stable DC voltage to the DC / DC, and the high-voltage side of the DC / DC adopts a dual closed-loop control method of submodule capacitor voltage outer loop-current inner loop, while the low-voltage side adopts a single current loop control method; in the high-voltage side control mode, the DC distribution network loses its DC voltage control capability, and the DC / DC needs to take over the DC voltage control, with the high-voltage side of the DC / DC adopting a dual closed-loop control method of DC voltage outer loop-current inner loop, and the low-voltage side adopting a dual closed-loop control method of submodule capacitor voltage outer loop-current inner loop; The step of adjusting the transmission power of the energy storage device via a controller, with reference to the adjustment value of the transmission power of the energy storage device, includes: Determine whether the DC / DC converter connecting the energy storage device and the DC distribution network is in low-voltage side control mode; Thus, the transmission power of the energy storage device is adjusted by controlling the high-voltage side submodule capacitor voltage and the low-voltage side current command. If not, the transmission power of the energy storage device can be adjusted by adjusting the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule through the controller.

2. The voltage equalization control method for energy storage devices according to claim 1, characterized in that, The step of adjusting the transmission power of the energy storage device by means of the controller to adjust the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side includes: Based on the adjustment value of the transmission power, calculate the adjustment values ​​of the capacitor voltage of the high-voltage side submodule and the current command of the low-voltage side; Based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command, the controller adjusts the high-voltage side submodule capacitor voltage and the low-voltage side current command to adjust the transmission power of the energy storage device.

3. The voltage equalization control method for energy storage devices according to claim 2, characterized in that, The adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side current command are respectively: ， in, The instantaneous voltage value of the energy storage device. The average voltage value of the energy storage device. The voltage value of the capacitor in the high-voltage side submodule. This refers to the low-voltage side current command value. This is the proportionality coefficient.

4. The voltage equalization control method for energy storage devices according to claim 1, characterized in that, The step of adjusting the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule through the controller includes: Based on the adjustment value of the transmission power, calculate the adjustment values ​​of the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule; Based on the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage, the controller adjusts the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage to adjust the transmission power of the energy storage device.

5. The voltage equalization control method for an energy storage device according to claim 4, characterized in that, The adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage are as follows: ， in, The instantaneous voltage value of the energy storage device. The average voltage value of the energy storage device. The voltage value of the capacitor in the high-voltage side submodule. The voltage value of the capacitor in the low-voltage side submodule. This is the proportionality coefficient.

6. A voltage equalization control system for an energy storage device, characterized in that, include: The detection module is used to acquire the instantaneous voltage values ​​of several energy storage devices and calculate the average voltage value of the several energy storage devices. A calculation module is used to obtain an adjustment value for the transmission power of each energy storage device based on the instantaneous voltage value and the average voltage value. The control module is used to adjust the transmission power of the energy storage device by referring to the adjustment value of the transmission power of the energy storage device, so as to realize the voltage equalization control of the plurality of energy storage devices. The DC / DC connecting the energy storage device and the DC distribution network has two operating modes: low-voltage side control mode and high-voltage side control mode. In the low-voltage side control mode, the DC distribution network provides a stable DC voltage to the DC / DC. The high-voltage side of the DC / DC adopts a double closed-loop control method of submodule capacitor voltage outer loop-current inner loop, and the low-voltage side adopts a single current loop control method. In the high-voltage side control mode, the DC distribution network loses its DC voltage control capability, and the DC / DC needs to take over the DC voltage control. The high-voltage side of the DC / DC adopts a double closed-loop control method of DC voltage outer loop-current inner loop, and the low-voltage side adopts a double closed-loop control method of submodule capacitor voltage outer loop-current inner loop. The control module includes: The judgment unit is used to determine whether the DC / DC converter connecting the energy storage device and the DC distribution network is in low-voltage side control mode. A control unit is used to adjust the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the low-voltage side current command through the controller when the DC / DC is in low-voltage side control mode. The control unit is also used to adjust the transmission power of the energy storage device by adjusting the capacitor voltage of the high-voltage side submodule and the capacitor voltage of the low-voltage side submodule when the DC / DC is in high-voltage side control mode.

7. The energy storage device pressure equalization control system according to claim 6, characterized in that, The control unit includes: The first calculation subunit is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side current command based on the adjustment value of the transmission power. The first control subunit is used to adjust the voltage of the high-voltage side submodule capacitor and the low-voltage side current command through a controller based on the adjustment value of the high-voltage side submodule capacitor voltage and the low-voltage side current command, so as to adjust the transmission power of the energy storage device.

8. The energy storage device pressure equalization control system according to claim 7, characterized in that, The adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side current command are respectively: ， in, The instantaneous voltage value of the energy storage device. The average voltage value of the energy storage device. The voltage value of the capacitor in the high-voltage side submodule. This refers to the low-voltage side current command value. This is the proportionality coefficient.

9. The energy storage device pressure equalization control system according to claim 6, characterized in that, The control unit includes: The second calculation subunit is used to calculate the adjustment values ​​of the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage based on the adjustment value of the transmission power. The second control subunit is used to adjust the voltage of the high-voltage side submodule and the voltage of the low-voltage side submodule by means of a controller, based on the adjustment values ​​of the voltage of the high-voltage side submodule and the voltage of the low-voltage side submodule, so as to adjust the transmission power of the energy storage device.

10. The energy storage device pressure equalization control system according to claim 9, characterized in that, The adjustment values ​​for the high-voltage side submodule capacitor voltage and the low-voltage side submodule capacitor voltage are as follows: ， in, The instantaneous voltage value of the energy storage device. The average voltage value of the energy storage device. The voltage value of the capacitor in the high-voltage side submodule. The voltage value of the capacitor in the low-voltage side submodule. This is the proportionality coefficient.

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