Energy storage system and its equipotential device, energy storage equipment, power plant

Abstract

This application discloses an energy storage system, an equalization device thereof, an energy storage device, and a power plant, in which when the equalization device is installed between a positive current bus and a negative DC bus of the energy storage system, the potential of the equipotential node in the equalization device is between the positive current bus voltage and the negative DC bus voltage of the energy storage system, thereby effectively reducing the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

Description

[Technical Field]

[0001] This application is based on and claims priority from the international patent application entitled "Energy Storage System and Its Equipotential Device, Energy Storage Equipment, and Power Plant," with application number PCT / CN2022 / 134399 and filing date November 25, 2022, the entire contents of which are hereby incorporated by reference into this application.

[0002] The present application relates to the field of batteries, and in particular to energy storage systems and their equipotential devices, energy storage equipment, and power plants. [Background technology]

[0003] In the related art, a power module of an energy storage system is connected in parallel to a plurality of battery modules, and the power module can be made to have the same potential as the negative electrode to prevent floating potential discharge in a high-voltage environment from damaging components in the energy storage system. Although the battery modules and other electronic devices connected in parallel to the power module in the energy storage system are also in a high-voltage environment, there is still no effective protective measure. Summary of the Invention

[0004] In view of the above problems, the present application provides an energy storage system, its equipotential device, energy storage equipment, and power plant, which can solve the problem in the related art that the internal insulation design requirements in the energy storage system are high.

[0005] According to a first aspect, there is provided an equalization device applied to an energy storage system, the equalization device including an equipotential node, and when the equalization device is installed between a positive current bus and a negative DC bus of the energy storage system, the potential of the equipotential node is between the positive current bus voltage and the negative DC bus voltage of the energy storage system.

[0006] When the equalization device according to the embodiment of the present disclosure is installed between the positive bus and the negative DC bus of the energy storage system, the potential of the equipotential node in the equalization device is between the positive bus voltage and the negative DC bus voltage of the energy storage system, which can effectively reduce the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0007] Optionally, the equalizing device includes a plurality of voltage dividing elements, the plurality of voltage dividing elements are connected in series, and the equalizing node is placed between the plurality of voltage dividing elements, thereby realizing voltage division.

[0008] Optionally, the voltage dividing element includes a resistor.

[0009] Optionally, the plurality of voltage dividing elements includes two resistors.

[0010] Optionally, the resistance values ​​of the two resistors are equal. When the two resistance values ​​are equal, the equalizing effect of the equalizing device is higher than when the two resistance values ​​are not equal.

[0011] Optionally, the resistance between the equipotential node and the positive DC bus is equal to the resistance between the equipotential node and the negative DC bus.

[0012] Optionally, the equalizing device includes a first connection end and a second connection end, the first connection end being suitable for being connected to the positive DC busbar and the second connection end being suitable for being connected to the negative DC busbar.

[0013] Optionally, the equalizing device further comprises a capacitor, wherein: the capacitor is connected between the equipotential node and the first connection end; or The capacitor is connected between the equipotential node and the second connection end.

[0014] Optionally, when there are two capacitors, one of the two capacitors is connected between the equipotential node and the first connection end, and the other of the two capacitors is connected between the equipotential node and the second connection end.

[0015] In the embodiments of the present disclosure, the resistor in the equalizing device may or may not be connected in parallel with the capacitor. The equalizing effect of the equalizing device is higher when the resistor is connected in parallel with the capacitor than when the resistor is not connected in parallel with the capacitor. Furthermore, the equalizing effect of the equalizing device is higher when the capacitor is connected in parallel with the voltage dividing element located between the equipotential node and the negative DC bus than when the capacitor is connected in parallel with the voltage dividing element located between the equipotential node and the positive DC bus. When there are two capacitors, the equalizing effect of the equalizing device is higher when the two capacitors have equal capacitance values ​​than when the capacitance values ​​of the two capacitors are unequal.

[0016] Optionally, the capacitor is a Y capacitance.

[0017] Optionally, the capacitor may be a capacitance, which is a Y capacitance and is connected in parallel with the resistor, so that when a surge occurs in the energy storage system, the capacitor conducts, which can effectively prevent the problem of the equipotential node floating due to the surge.

[0018] Furthermore, compared to when the capacitor is connected in parallel to the voltage divider element located between the equipotential node and the positive DC bus, when the capacitor is connected in parallel to the voltage divider element located between the equipotential node and the negative DC bus, this is consistent with the method of equalizing the potential with the negative electrode of the power unit, and the pressure difference between the energy storage device and the power unit is small, so the insulation risk is smaller.

[0019] Optionally, the equipotential node is suitable for being connected to a metal member in the energy storage system, which can effectively reduce the voltage between the metal member and the busbar, further effectively reduce the internal insulation design requirements of the energy storage system, and effectively avoid the risk of single-point-of-failure insulation failure.

[0020] Optionally, the metal member includes one or more of an electrical cabinet case, an electrical box case, a main control box case, a battery case, a control device case, a ground terminal of the control device, a relay case, a power module case, an electrical converter case, and a water cooling plate.

[0021] Optionally, the equipotential points are connected to the metal members by wire, welding or bolt locking.

[0022] According to a second aspect, there is provided an energy storage system, the energy storage system comprising: a power unit configured to convert AC power and provide it to positive and negative DC buses or transmit electrical energy; The equalization device according to the above aspect, the equalization device is installed between positive and negative DC buses and includes an equipotential node; and an energy storage device, the energy storage device being connected in parallel between the positive and negative DC buses, and a metal member of the energy storage device being connected to an equipotential node.

[0023] Optionally, the energy storage device includes an electrical cabinet, at least one battery installed in the electrical cabinet, the battery being connected between positive and negative DC busbars, and the metal member including a case of the electrical cabinet, thereby realizing equipotential between the case of the electrical cabinet and the equipotential node.

[0024] Optionally, the energy storage device further includes an electrical box installed corresponding to each battery, the electrical box installed in the electrical cabinet, and a case of the electrical box connected to a case of the electrical cabinet, thereby realizing an equipotential between the case of the electrical box and the equipotential node.

[0025] Optionally, the energy storage device further includes a main control box, and the case of the main control box is connected to the case of the electrical cabinet, thereby realizing an equipotential between the case of the main control box and the equipotential node.

[0026] Optionally, the potential equalization device is installed in the main control box.

[0027] Optionally, a main positive switch, a main negative switch, a pre-charge switch and a pre-charge resistor are further installed in the main control box, the main positive switch is connected in series to the direct current bus bar of the positive and negative DC bus bars, the pre-charge switch is connected in series to the pre-charge resistor and then connected in parallel to the main positive switch, the main negative switch is connected in series to the negative DC bus bar of the positive and negative DC bus bars, one end of the equalizing device is connected between the main positive switch and the positive pole of the battery, and the other end of the equalizing device is connected between the main negative switch and the negative pole of the battery.

[0028] Alternatively, the main control box is installed outside the electrical cabinet, or the main control box is installed inside the electrical cabinet.

[0029] Optionally, an equalizing device is installed in the electrical cabinet, and one end of the equalizing device is connected to the positive pole of the battery, and the other end of the equalizing device is connected to the negative pole of the battery.

[0030] Optionally, if there are multiple batteries, the multiple batteries are connected in series.

[0031] Optionally, when there are multiple energy storage devices, there are multiple equalization devices, and the multiple energy storage devices are respectively connected in parallel between the positive and negative DC buses, and the metal members of each energy storage device are connected to the equipotential nodes configured on the corresponding equalization devices. The equalization devices are installed on each energy storage device, and all the metal members of each energy storage device are equipotential with the equipotential nodes. This implementation method can also accommodate the insulation detection function of multiple energy storage devices connected in parallel.

[0032] Alternatively, when there are multiple energy storage devices, the multiple energy storage devices are connected in parallel between the positive and negative DC buses, and the metal members of any one of the multiple energy storage devices are connected to an equipotential node, and the metal members of the multiple energy storage devices are connected in series, and each energy storage device is equipotential with the equipotential node, so the design of this implementation is relatively simple, and in an application scenario where multiple electrical cabinets are concentrated in one cabin (e.g., a container), the potential distribution within the container is relatively uniform, and insulation problems can be avoided.

[0033] Optionally, the power unit is installed in a power box, and the case of the power box is connected to the negative DC bus bar of the positive and negative DC bus bars.

[0034] Optionally, the power unit is configured with power devices as a half-bridge circuit, a full-bridge circuit or an energy storage converter.

[0035] Optionally, a bypass switch is installed at the input of the power unit.

[0036] According to a third aspect, there is provided an energy storage device including the energy storage system according to the above aspect.

[0037] Optionally, the energy storage system is multiple and the multiple energy storage systems are cascaded.

[0038] According to a fourth aspect, there is provided a power plant including the energy storage device according to the above aspect.

[0039] Additional aspects and advantages of the disclosure will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a structural schematic diagram of an equalizing device according to an embodiment of the present disclosure; [Figure 2] FIG. 10 is a structural schematic diagram of another equalizing device according to an embodiment of the present disclosure. [Figure 3] FIG. 10 is a structural schematic diagram of yet another equalizing device according to an embodiment of the present disclosure. [Figure 4] FIG. 10 is a structural schematic diagram of yet another equalizing device according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a structural schematic diagram of an energy storage system according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a structural schematic diagram of another energy storage system according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a structural schematic diagram of yet another energy storage system according to an embodiment of the present disclosure. [Figure 8] FIG. 10 is a structural schematic diagram of yet another energy storage system according to an embodiment of the present disclosure. [Figure 9] FIG. 10 is a structural schematic diagram of yet another energy storage system according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a structural schematic diagram of yet another energy storage system according to an embodiment of the present disclosure. [Figure 11] FIG. 10 is a structural schematic diagram of yet another energy storage system according to an embodiment of the present disclosure. [Figure 12] FIG. 1 is a structural schematic diagram of an energy storage device according to an embodiment of the present disclosure. [Figure 13] FIG. 2 is a structural schematic diagram of another energy storage device according to an embodiment of the present disclosure. [Figure 14] FIG. 10 is a structural schematic diagram of yet another energy storage device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0041] The following detailed description of the embodiments of the present disclosure is provided in the drawings, in which the same or similar reference numerals throughout the drawings represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and are used to interpret the present disclosure, but should not be construed as limitations on the present disclosure.

[0042] In a conventional energy storage system, a power module is connected in series with a single battery module. When the system voltage level is relatively low, for example, 1500 volts (V) or less, the battery module case is generally directly grounded, and the high-voltage circuit and the battery module case only need to meet the dielectric strength requirements at the corresponding voltage level. In a high-voltage DC transmission and distribution system, the system voltage level is very high, for example, reaching tens of kilovolts to hundreds of kilovolts. Therefore, the power module housing in this energy storage system cannot be directly grounded, and a high-voltage support insulator is generally used to support the power module. However, to prevent floating potential discharge in a high-voltage environment from damaging primary and secondary components in the energy storage system, the power module housing still needs to be potential-clamped, typically by using a method of equalizing the negative electrode, i.e., the power module housing is connected to the negative electrode.

[0043] The power module included in the new high-voltage energy storage system in the related art is connected in parallel to a plurality of battery modules, and this power module is equipotential with the negative electrode. If the new high-voltage energy storage system adopts a method in which the battery modules connected in parallel to the power module are also equipotential with the negative electrode, the following problems arise.

[0044] First, there is a high risk of single-point insulation failure in the battery module. Because the negative electrode is connected to the metal housing (which is equivalent to an insulation failure at one end of the battery module), if another insulation failure occurs in the battery module, it is equivalent to a short circuit between the positive and negative electrodes of the battery module, which poses a significant safety risk.

[0045] Second, connecting the negative pole to the housing affects the insulation detection function of the battery module. The insulation detection function requires that the voltage across the battery cannot be directly measured, and in this case, the insulation resistance is calculated as 0. At the same time, if the battery module is made up of multiple battery packs connected in parallel and each battery pack is at the same potential, the insulation detection function will also interfere with each other.

[0046] Third, the voltage between the case of the electrical box and the case of the battery cell is relatively high, that is, the voltage of the entire energy storage system is relatively high. If the case of the electrical box is equipotential with the negative terminal of the bus, the maximum voltage difference between it and the case of the battery is the voltage of the entire battery module, and the voltage between the case of the electrical box and the case of the battery is relatively high.

[0047] 1 is a structural schematic diagram of an equalization device according to an embodiment of the present disclosure. The equalization device 10 can be applied to an energy storage system. The equalization device 10 may include an equipotential node. When the equalization device 10 is installed between the positive current bus D+ and the negative DC bus D- of the energy storage system, the potential of the equipotential node is between the positive current bus D+ voltage and the negative DC bus D- voltage of the energy storage system. This can effectively reduce the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus D+ voltage and the negative DC bus D- voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0048] In summary, the embodiments of the present disclosure provide an equalization device, which, when installed between a positive current bus and a negative DC bus of an energy storage system, has an equipotential node in the equalization device that is between the positive current bus voltage and the negative DC bus voltage of the energy storage system, thereby effectively reducing the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0049] In an embodiment of the present disclosure, the equalizing device 10 may include a plurality of voltage dividing elements, which are connected in series, and the equalizing node K is located between the plurality of voltage dividing elements, and optionally, the equalizing node K may be the midpoint of the plurality of voltage dividing elements.

[0050] Referring to FIG. 2, each voltage dividing element may include a resistor, and the voltage dividing element may include one or more resistors. When the voltage dividing element includes multiple resistors, the multiple resistors may be connected in series and / or in parallel.

[0051] Alternatively, the resistance value between the equipotential node K and the positive DC bus D+ may be equal to the resistance value between the equipotential node K and the negative DC bus D-, thereby effectively reducing the internal insulation design requirements of the energy storage system, i.e., the sum of the resistance values ​​of the resistors located between the equipotential node K and the positive DC bus D+ is equal to the sum of the resistance values ​​of the resistors located between the equipotential node K and the negative DC bus D-.

[0052] Optionally, the plurality of voltage dividing elements may include two resistors connected in series, and the two resistors are further adapted to be connected to a direct current bus D+ and a negative DC bus D-. The equipotential node K may be located between the two resistors. For example, referring to FIG. 2, the equipotential node K may be located at the midpoint of the two resistors (i.e., the first resistor R1 and the second resistor R2).

[0053] Optionally, the resistance values ​​of the two resistors may be equal or unequal. As can be appreciated, equal resistance values ​​of the two resistors may refer to the two resistance values ​​being absolutely equal or approximately equal. Absolute equality refers to the difference between the two resistance values ​​being zero, and approximately equality refers to the absolute value of the difference between the two resistance values ​​being less than a first difference threshold and being greater than zero.

[0054] In the embodiment of the present disclosure, when the two resistance values ​​are equal, the voltage between the metal member and the busbar in the energy storage system can be reduced by half when the equipotential node K is installed at the midpoint of the two resistors, compared to when the two resistance values ​​are not equal, and the equipotential effect of the equalizer 10 is higher.

[0055] 3 and 4, the potential equalizer 10 may include a first connection end u1 and a second connection end u2, where the first connection end u1 is suitable for connection to the positive DC bus D+ and the second connection end u2 is suitable for connection to the negative DC bus D-. The first connection end u1 is further connected to one end of a plurality of voltage dividing elements, and the second connection end u2 is further connected to the other end of the plurality of voltage dividing elements. For example, referring to FIGS. 3 and 4, the first connection end u1 is further connected to the first resistor R1, and the second connection end u2 is further connected to the second resistor R2.

[0056] The equalizing device 10 may further include a capacitor C1, which is connected between the equipotential node K and the first connection end u1, i.e., the capacitor C1 is connected in parallel to a voltage dividing element located between the positive DC bus D+ and the equipotential node K. For example, referring to FIG. 3, the capacitor C1 is connected in parallel to a first resistor R1. Alternatively, the capacitor C1 is connected between the equipotential node K and the second connection end u2, i.e., the capacitor C1 is connected in parallel to a voltage dividing element located between the negative DC bus D- and the equipotential node K. For example, referring to FIG. 4, the capacitor C1 is connected in parallel to a second resistor R2.

[0057] When there are two capacitors C1, one of the two capacitors C1 is connected between the equipotential node K and the first connection end u1, and the other of the two capacitors C1 is connected between the equipotential node K and the second connection end u2. That is, one of the two capacitors C1 is connected in parallel to a voltage dividing element located between the positive DC bus D+ and the equipotential node K, and the other is connected in parallel to a voltage dividing element located between the negative DC bus D- and the equipotential node K.

[0058] In the case of two capacitors, the capacitance values ​​of the two capacitors may or may not be equal. As can be understood, the equal capacitance values ​​of the two capacitors may refer to the two capacitance values ​​being absolutely equal or approximately equal. Absolute equality refers to the difference between the two capacitance values ​​being zero, and approximately equal refers to the absolute value of the difference between the two capacitance values ​​being less than a second difference threshold and being greater than zero.

[0059] When the two capacitance values ​​are equal, the equalizing effect of the equalizing device 10 is higher than when the two capacitance values ​​are not equal.

[0060] In the embodiment of the present disclosure, the voltage dividing element in the equalizing device 10 may or may not be connected in parallel to the capacitor C1. When the voltage dividing element is connected in parallel to the capacitor C1, the equalizing effect of the equalizing device is higher than when the voltage dividing element is not connected in parallel to the capacitor C1.

[0061] Optionally, the capacitor C1 may be a Y capacitance. Because the capacitor C1 is a Y capacitance and is connected in parallel to the voltage dividing element, when a surge occurs in the energy storage system, the capacitor C1 will conduct, which can effectively prevent the problem of the equipotential node floating due to the surge.

[0062] Furthermore, compared to when the capacitor C1 is connected in parallel to the voltage divider element located between the positive DC bus D+ and the equipotential node K, when the capacitor C1 is connected in parallel to the voltage divider element located between the negative DC bus D- and the equipotential node K, the method of equalizing the potential with the negative electrode of the power unit is more consistent, and the pressure difference between the energy storage device and the power unit is smaller, so the insulation risk is smaller.

[0063] In the embodiments of the present disclosure, the equipotential node K is further suitable for connection to a metal member in the energy storage system, thereby effectively reducing the voltage between the metal member and the busbar, and further effectively reducing the internal insulation design requirements of the energy storage system. If the equipotential node K is the midpoint of multiple voltage dividing elements and the resistance value between the equipotential node K and the DC busbar D+ is equal to the resistance value between the equipotential node K and the DC busbar D-, the voltage between the metal member and the busbar can be reduced by half, and further effectively reducing the internal insulation design requirements of the energy storage system.

[0064] The equipotential point K may be connected to a metal member by wire, welding, or bolt locking. The metal member may include one or more of an electrical cabinet case, an electrical box case, a main control box case, a battery case, a control device case, a grounding terminal of the control device, a relay case, a power module case, an electric converter case, and a water-cooled plate. The control device is used to control charging and discharging, and the power module is used to convert AC power. The electric converter may be a direct current / alternating current (DC / AC), AC / DC, or DC / DC device. The metal member is connected to the equipotential point K, which can effectively avoid the risk of single-point-of-fault insulation failure.

[0065] Optionally, the metal member may include a case of an electronic device, i.e., the equipotential node K is further suitable for being connected to a case of an electronic device in the energy storage system. Optionally, the case of the electronic device may include one or more of a case of an electrical cabinet, a case of an electrical box, a case of a main control box, a case of a battery, a case of a control device, a case of a relay, a case of a power module, and a case of an electric converter.

[0066] In summary, the embodiments of the present disclosure provide an equalization device, which, when installed between a positive current bus and a negative DC bus of an energy storage system, has an equipotential node in the equalization device that is between the positive current bus voltage and the negative DC bus voltage of the energy storage system, thereby effectively reducing the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0067] FIG. 5 is a structural schematic diagram of an energy storage system according to an embodiment of the present disclosure. As shown in FIG. 5, the energy storage system 100 may include a power unit 20, an equalizing device 10, and an energy storage device 30.

[0068] Here, the power unit 20 is configured to convert AC power and provide it to positive and negative DC buses or transmit electrical energy.

[0069] The equalizing device 10 is installed between the positive and negative DC bus bars and includes an equipotential node.

[0070] The energy storage device 30 is connected in parallel between the positive and negative DC buses, and the metal members of the energy storage device 30 are connected to the equipotential nodes.

[0071] Alternatively, the energy storage device 30 may be multiple, and the multiple energy storage devices 30 are connected in parallel between the positive and negative DC buses, and the metal members of the energy storage devices are connected to the equipotential node K.

[0072] To summarize, an embodiment of the present disclosure provides an energy storage system, in which when an equalization device in the energy storage system is installed between a positive current bus and a negative DC bus of the energy storage system, the potential of the equipotential node in the equalization device is between the positive current bus voltage and the negative DC bus voltage of the energy storage system, thereby effectively reducing the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0073] 6, 7, and 8, the energy storage device 30 may include an electrical cabinet 31 and at least one battery B installed in the electrical cabinet 31. If the electrical cabinet 31 includes multiple batteries B, the multiple batteries B are connected in series. FIGS. 6 to 8 illustrate an example in which the energy storage device 30 includes two batteries B connected in series. The battery B is connected between the positive and negative DC busbars, and the metal member may include the case 31a of the electrical cabinet 31. That is, the case 31a of the electrical cabinet 31 is connected to the equipotential node K, which can effectively reduce the internal insulation design requirements of the energy storage module.

[0074] 6 to 8, the energy storage device 30 may further include an electric box 32 installed corresponding to each battery B, and the electric box 32 is installed in the electric cabinet 31, and the case 32a of the electric box 32 is connected to the case 31a of the electric cabinet 31. The case 31a of the electric cabinet 31 is connected to the equipotential node K, and since the case 32a of each electric box 32 is connected to the case 31a of the electric cabinet 31, the case 32a of each electric box 32 is also connected to the equipotential node, that is, the metal member may further include the case 32a of each electric box 32. This can effectively reduce the voltage between the battery B and the case 31a of the electric cabinet 31, and further effectively reduce the internal insulation design requirements of the energy storage system. Furthermore, if this equipotential node K is the midpoint between the first and second resistors of the at least two resistors, and the sum of the resistance values ​​of the resistors located between this equipotential node K and the DC bus D+ is equal to the sum of the resistance values ​​of the resistors located between the equipotential node K and the DC bus D-, the voltage between the battery B and the case 31a of the electrical cabinet 31 can be reduced by half, which further effectively reduces the internal insulation design requirements of the energy storage system.

[0075] 7 and 8, the energy storage device 30 may further include a main control box 33, and a case 33a of the main control box 33 is connected to the case 31a of the electrical cabinet 31. The case 31a of the electrical cabinet 31 is connected to the equipotential node K, and since the case 33a of the main control box 33 is connected to the case 31a of the electrical cabinet 31, the case 33a of the main control box 33 is also connected to the equipotential node K, that is, the metal member may further include the case 33a of the main control box 33, which can effectively reduce the internal insulation design requirements of the energy storage system.

[0076] In one alternative implementation manner of the embodiments of the present disclosure, referring to Figures 6 and 7, the potential equalization device 10 may be installed in the main control box 33, and a main positive switch S1, a main negative switch S2, a pre-charge switch S3 and a pre-charge resistor r may be further installed in the main control box 33.

[0077] Here, the main positive switch S1 is connected in series to the DC bus D+, and the pre-charge switch S3 is connected in series to a pre-charge resistor r and then connected in parallel to the main positive switch S1. That is, the pre-charge switch S3 and the pre-charge resistor r, which are connected in series in this order, are connected in parallel to the main positive switch S1. The main negative switch S2 is also connected in series to the negative DC bus D-. One end of the equalizing device 10 is connected between the main positive switch S1 and the positive electrode of battery B, and the other end of the equalizing device 10 is connected between the main negative switch S2 and the negative electrode of battery B.

[0078] Referring to Figures 6 and 7, the first connection end u1 of this equalizing device 10 is connected between the main positive switch S1 and the positive electrode of battery B, and the second connection end u2 of this equalizing device 10 is connected between the main negative switch S2 and the negative electrode of battery B.

[0079] This equipotential node K is directly connected to the case 33a of the main control box 33, which is connected to the case 31a of the electrical cabinet 31, and which is connected to the case 32a of each electrical box 32, so that this equipotential node K is connected to the case 33a of the main control box 33, the case 31a of the electrical cabinet 31, and the case of each electrical box 32.

[0080] In the embodiment of the present disclosure, the main control box 33 may be installed inside the electrical cabinet 31, or as shown in Figures 6 and 7, the main control box 33 may be installed outside the electrical cabinet 31.

[0081] Referring to Figures 6 and 7, the main control box may further include a fuse F, and there may be two fuses F, one connected in series to the main positive switch S1 and the other connected in series to the main negative switch S2.

[0082] In another alternative implementation of the embodiment of the present disclosure, referring to FIG. 8 , the equalizing device 10 may be installed in an electrical cabinet 31, and one end of the equalizing device 10 is connected to the positive terminal of battery B, and the other end of the equalizing device 10 is connected to the negative terminal of battery B.

[0083] Optionally, the first connection terminal u1 of this potential equalizing device 10 is connected to the positive electrode of the battery B, and the second connection terminal u2 is connected to the negative electrode of the battery B.

[0084] This equipotential node K is directly connected to the case 31a of the electrical cabinet 31, the case 33a of the main control box 33 is connected to the case 31a of the electrical cabinet 31, and the case 31a of the electrical cabinet 31 is connected to the case 32a of each electrical box 32, so this equipotential node K is connected to the case 33a of the main control box 33, the case 31a of the electrical cabinet 31 and the case of each electrical box 32.

[0085] When there are a plurality of energy storage devices 30, in one alternative implementation manner of the embodiment of the present disclosure, referring to Fig. 9, there may be a plurality of equalization devices 10, and the plurality of equalization devices 10 correspond one-to-one to the plurality of energy storage devices 30, and the plurality of energy storage devices 30 are respectively connected in parallel between the positive and negative DC bus bars, and the metal member of each energy storage device 30 (e.g., the case 33a of the main control box 33) is connected to the equipotential node K configured on the corresponding equalization device 10. Fig. 8 describes, as an example, that two energy storage devices 30 are connected in parallel between the positive and negative DC bus bars.

[0086] In this case, each energy storage device 30 is provided with an equalizing device 10, and as shown in Figures 6 to 8, when the main control box 33 is provided in the electrical cabinet 31, the equalizing device 10 may be provided in the main control box 33 or between the main control box 33 and the electrical box 32. When the main control box 33 is provided outside the electrical cabinet 31, the equalizing device 10 may be provided in the main control box 33 or in the electrical cabinet 31. The embodiments of the present disclosure are not limited thereto.

[0087] In this implementation, the equalizing device is installed in each energy storage device, and the metal members in each energy storage device are at the same potential as the equipotential node K. This implementation can also be adapted to the insulation detection function of multiple energy storage devices connected in parallel.

[0088] In another alternative implementation manner of the embodiments of the present disclosure, referring to FIG. 10 , the plurality of energy storage devices 30 are respectively connected in parallel between the positive and negative DC buses, and the metal components of any one of the plurality of energy storage devices 30 (e.g., the case 33a of the main control box 33) are connected to the equipotential node K, and the metal components of the plurality of energy storage devices 30 (e.g., the case 33a of the main control box 33) are connected in series.

[0089] In the embodiment of the present disclosure, the power unit 20 may be installed in a power box 40, and a case 40a of the power box 40 is connected to the negative DC bus D- of the positive and negative DC buses.

[0090] In this implementation, each energy storage device is equipotential with this equipotential node K, and the design of this implementation is relatively simple. At the same time, in an application scenario in which multiple electrical cabinets are concentrated in one cabin (e.g., a container), the potential distribution within the container is also relatively uniform, and insulation problems can be avoided.

[0091] Referring to Figures 9 and 10, a bypass switch S4 is installed at the input end of the power unit 20, and the bypass switch S4 is used to turn off when a fault occurs in the energy storage system and to turn on when the energy storage system operates normally.

[0092] 9 and 10, the power unit 20 may be configured as a half-bridge circuit using power devices, and the power devices may include a first power switch S5, a second power switch S6, an energy storage capacitor C2, and a voltage dividing resistor R3. One end of the first power switch S5 is connected to one end of the bypass switch S4 and one end of the second power switch S6, respectively, the other end of the first power switch S5 is connected to one end of the energy storage capacitor C2, one end of the voltage dividing resistor R3, and the positive DC bus D+, respectively, and the other end of the second power switch S6 is connected to the other end of the energy storage capacitor C2, the other end of the voltage dividing resistor R3, and the negative DC bus D-, respectively.

[0093] Alternatively, referring to FIG. 11, the power unit 20 may be configured as a full bridge circuit with power devices, which may include a first power switch S5, a second power switch S6, a third power switch S7, and a fourth power switch S8, an energy storage capacitor C2, and a voltage dividing resistor R3.

[0094] One end of the first power switch S5 is connected to one end of the bypass switch S4 and one end of the second power switch S6, the other end of the first power switch S5 is connected to one end of the third power switch S7, one end of the energy storage capacitor C2, one end of the voltage dividing resistor R3, and the positive DC bus D+, and the other end of the second power switch S6 is connected to the other end of the energy storage capacitor C2, the other end of the voltage dividing resistor R3, and the negative DC bus D-. The other end of the fourth power switch S8 is also connected to the other end of the bypass switch S4.

[0095] Alternatively, the power unit 20 may be configured as an energy storage converter (PCS, power conversion system) using a power device.

[0096] To summarize, an embodiment of the present disclosure provides an energy storage system in which, when an equalization device in the energy storage system is installed between a positive current bus and a negative DC bus of the energy storage system, the potential of the equipotential node in the equalization device is between the positive current bus voltage and the negative DC bus voltage of the energy storage system, thereby effectively reducing the voltage between the bus in the energy storage system and the metal member connected to the equipotential node, so that the reduced voltage is located between the positive current bus voltage and the negative DC bus voltage, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0097] An embodiment of the present disclosure provides an energy storage device, which may include the energy storage system described in the above embodiments, for example, the energy storage system shown in any of FIGS. 5 to 11.

[0098] 12 to 14, the energy storage system 100 is plural, and the plural energy storage systems 100 are cascaded.

[0099] 12, the energy storage device 1000 may be a DC direct-connect energy storage device that can be used to realize functions such as power output and energy storage based on the DC power received and transmitted from the positive and negative DC buses. Referring to FIG. 12, the energy storage device 1000 may further include an isolation knife switch M, a starting resistor R4, a starting switch S9, and a first reactor L1. The starting resistor R4 is used to protect the energy storage device 1000 during startup of the energy storage device. One end of the isolation knife switch M is connected to the positive DC bus P+, and the other end of the isolation knife switch M is connected to one end of the starting resistor R4 and one end of the starting switch S9, respectively. The other end of the starting resistor R4 and the other end of the starting switch S9 are both connected to one end of a first reactor L1, the other end of the first reactor L1 is connected to one end of a plurality of cascaded energy storage systems 100, and the other ends of the plurality of cascaded energy storage systems 100 are connected to the negative DC bus P-. In this implementation, the power unit in the energy storage system is used to transmit DC power.

[0100] 13, the energy storage device 1000 may also be a modular multi-level energy storage device, which can achieve functions such as AC-DC conversion, active or reactive output control, etc. Referring to FIG. 13, the energy storage device 1000 may include six converter bridge arms, each of which may include a plurality of cascaded energy storage systems 100 and a second reactor L2. One end of the second reactor L2 in each converter bridge arm is connected to an AC bus X, and the other end of the second reactor L2 in each converter bridge arm is connected to one end of a plurality of cascaded energy storage systems 100, the other ends of which are connected to a DC bus W. The energy storage device 1000 is used to convert DC power transmitted by the DC bus W into AC power and transmit it to power consumers via the AC bus X.

[0101] 14 , the energy storage device 1000 may also be a cascaded energy storage device, which can be used to realize functions such as power output and energy storage based on received AC power transmitted from an AC bus. The energy storage device 1000 may include three converter bridge arms, each of which may include a third reactor L3 and a plurality of cascaded energy storage systems 100, where one end of the third reactor L3 of each converter bridge arm is connected to the AC bus X, the other end of the third reactor L3 of each converter bridge arm is connected to one end of the plurality of cascaded energy storage systems 100, and the other ends of the plurality of cascaded energy storage systems 100 included in the three converter bridge arms are connected to each other.

[0102] An embodiment of the present disclosure provides a power plant, which may include the energy storage device described in the above embodiments, for example, the energy storage device 1000 shown in FIGS. 12 to 14 above.

[0103] It should be noted that the logic and / or steps illustrated in flowcharts or otherwise described herein, e.g., ordered listings of executable instructions that could be used to implement logical functions, may be embodied in any computer-readable medium for use with or in combination with an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system capable of obtaining instructions from and executing instructions on an instruction execution system, device, or device). As used herein, a "computer-readable medium" may be any device that contains, stores, communicates, propagates, or transmits a program for use with an instruction execution system, device, or device, or in combination with such an instruction execution system, device, or device. More specific examples (non-exhaustive list) of computer-readable media include electrical connections having one or more wires (electronic devices), portable computer disk cartridges (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disk read-only memories (CD-ROMs). Furthermore, the computer-readable medium may be paper or other suitable medium on which the program may be printed, since the program may be obtained electronically, for example by optically scanning the paper or other medium and subsequently editing, interpreting, or processing in any other suitable manner as necessary, and then storing it in a computer memory. It should be understood that each part of the present disclosure may be realized in hardware, software, firmware, or a combination thereof. In the above embodiments, several steps or methods may be realized in software or firmware stored in a memory and executed by a suitable instruction execution system.For example, when implemented in hardware, as in other embodiments, the implementation may be implemented using any one or combination of techniques known in the art, such as discrete logic circuits having logic gate circuits for implementing the logical functions of data signals, dedicated integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0104] In the description herein, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with this embodiment or example are included in at least one embodiment or example of the present disclosure. In the description herein, general expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. In describing the present disclosure, it should be understood that the orientations or positional relationships indicated by the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. are orientations or positional relationships shown based on the drawings, and are intended merely to facilitate and simplify the description of the present disclosure, and do not indicate or imply that the referred-to devices or elements must have a particular orientation or be configured and operated in a particular orientation, and therefore should not be understood as limitations on the present disclosure.

[0105] It should be noted that terms such as "first" and "second" used in the examples of the present disclosure are used for descriptive purposes only and should not be understood as indicating or implying relative importance or the number of technical features indicated in the examples. Therefore, in the examples of the present disclosure, terms such as "first" and "second" may limit features and explicitly or implicitly indicate that the example includes at least one of the features. In the description of the present disclosure, unless otherwise clearly and specifically limited in the examples, the word "plurality" means at least two or more than two, for example, two, three, four, etc.

[0106] In this disclosure, unless otherwise specified or limited in the examples, the terms "attached," "connected," "connected," and "fixed" appearing in the examples should be understood in a broad sense. For example, a connection may be a fixed connection, a detachable connection, or an integral connection. As can be understood, it may be a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, or an internal communication or an interactive relationship between two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in the present disclosure depending on the specific implementation situation. In this disclosure, unless otherwise specified or limited, a first feature being "above" or "below" a second feature may mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature via an intermediate medium. Furthermore, a first feature being "above," "above," or "on the upper surface" of a second feature may mean that the first feature is directly above or diagonally above the second feature, or may simply mean that the horizontal height of the first feature is higher than that of the second feature. A first feature being "below," "underneath," or "underside" of a second feature means that the first feature is directly below or diagonally below the second feature, or simply that the first feature has a lower horizontal height than the second feature.

[0107] Although the embodiments of the present disclosure have been shown and described above, it should be understood that the above embodiments are illustrative and should not be construed as limiting the present disclosure, and that those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. 1. An equalization device applied to an energy storage system, the equalization device comprising an equipotential node, wherein when the equalization device is installed between a positive current bus and a negative DC bus of the energy storage system, the potential of the equipotential node is between the positive current bus voltage and the negative DC bus voltage of the energy storage system.

2. 2. The equalizing device according to claim 1, wherein the equalizing device includes a plurality of voltage dividing elements, the plurality of voltage dividing elements being connected in series, and the equalizing node being located between the plurality of voltage dividing elements.

3. 3. The potential equalizer according to claim 2, wherein the voltage dividing element includes a resistor.

4. 4. The potential equalizer according to claim 3, wherein the plurality of voltage dividing elements include two of the resistors.

5. 5. The potential equalizer according to claim 4, wherein the two resistors have the same resistance value.

6. 4. The equalizing device according to claim 3, wherein a resistance value between the equipotential node and the positive DC bus is equal to a resistance value between the equipotential node and the negative DC bus.

7. 7. The potential equalizer according to claim 1, wherein the potential equalizer includes a first connection end and a second connection end, the first connection end being suitable for being connected to the positive DC busbar, and the second connection end being suitable for being connected to the negative DC busbar.

8. The equalizing device further includes a capacitor, wherein: the capacitor is connected between the equipotential node and the first connection end; or 8. The equalizing device according to claim 7, wherein the capacitor is connected between the equipotential node and the second connection end.

9. 9. The equalizing device according to claim 8, wherein, when there are two capacitors, one of the two capacitors is connected between the equipotential node and the first connection end, and the other of the two capacitors is connected between the equipotential node and the second connection end.

10. 9. The equipotential device according to claim 8, wherein the capacitor is a Y-capacitance.

11. 11. An equalizing device according to any one of claims 1 to 10, characterized in that the equipotential node is suitable for being connected to a metallic member in the energy storage system.

12. 12. The potential equalization device according to claim 11, wherein the metal members include one or more of an electrical cabinet case, an electrical box case, a main control box case, a battery case, a control device case, a ground terminal of the control device, a relay case, a power module case, an electric converter case, and a water-cooled plate.

13. The equipotential device according to claim 11, wherein the equipotential point is connected to the metal member by a wire, welding, or bolt locking.

14. 1. An energy storage system comprising: a power unit configured to convert AC power and provide it to positive and negative DC buses or transmit electrical energy; 14. The equalizing device according to claim 1, wherein the equalizing device is installed between the positive and negative DC buses and includes an equipotential node; 1. An energy storage system comprising: an energy storage device connected in parallel between the positive and negative DC buses, and a metal member of the energy storage device connected to the equipotential node.

15. 15. The energy storage system of claim 14, wherein the energy storage device includes an electrical cabinet and at least one battery installed in the electrical cabinet, the battery being connected between the positive and negative DC bus bars, and the metal member includes a case of the electrical cabinet.

16. 16. The energy storage system of claim 15, wherein the energy storage device further includes an electrical box installed corresponding to each of the batteries, the electrical box being installed in the electrical cabinet, and a case of the electrical box being connected to a case of the electrical cabinet.

17. 16. The energy storage system of claim 15, wherein the energy storage device further includes a main control box, the case of the main control box being connected to the case of the electrical cabinet.

18. 18. The energy storage system of claim 17, wherein the equalizing device is installed in the main control box.

19. 19. The energy storage system of claim 18, further comprising: a main positive switch, a main negative switch, a pre-charge switch, and a pre-charge resistor installed in the main control box; the main positive switch connected in series to a direct current bus bar of the positive and negative DC bus bars; the pre-charge switch connected in series to the pre-charge resistor and then connected in parallel to the main positive switch; the main negative switch connected in series to a negative DC bus bar of the positive and negative DC bus bars; one end of the equalizing device connected between the main positive switch and the positive electrode of the battery, and the other end of the equalizing device connected between the main negative switch and the negative electrode of the battery.

20. 20. The energy storage system of claim 18, wherein the main control box is installed outside an electrical cabinet, or the main control box is installed inside the electrical cabinet.

21. 16. The energy storage system of claim 15, wherein the equalizing device is installed in the electrical cabinet, and one end of the equalizing device is connected to the positive pole of the battery, and the other end of the equalizing device is connected to the negative pole of the battery.

22. 22. The energy storage system of claim 15, wherein when there are a plurality of batteries, the batteries are connected in series.

23. 23. The energy storage system according to claim 14, wherein when there are a plurality of energy storage devices, there are a plurality of equipotential devices, the plurality of energy storage devices are respectively connected in parallel between the positive and negative DC buses, and a metal member of each of the energy storage devices is connected to an equipotential node configured in the corresponding equipotential device.

24. 18. The energy storage system according to claim 14, wherein, when there are a plurality of energy storage devices, the plurality of energy storage devices are respectively connected in parallel between the positive and negative DC buses, and a metal member of any one of the plurality of energy storage devices is connected to the equipotential node, and a metal member of the plurality of energy storage devices is connected in series.

25. 25. The energy storage system according to claim 14, wherein the power unit is installed in a power box, and a case of the power box is connected to a negative DC bus bar of the positive and negative DC bus bars.

26. 25. The energy storage system according to claim 14, wherein the power unit is configured as a half-bridge circuit, a full-bridge circuit, or an energy storage converter using power devices.

27. 25. The energy storage system according to claim 14, wherein a bypass switch is installed at the input end of the power unit.

28. 28. An energy storage device comprising an energy storage system according to any one of claims 14 to 27.

29. 30. The energy storage device of claim 28, wherein the energy storage system is a plurality of energy storage systems, and the plurality of energy storage systems are cascaded.

30. 30. A power plant comprising an energy storage device according to claim 28 or 29.

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