Energy storage system and equipotential device thereof, energy storage equipment and power station

Abstract

The invention discloses an energy storage system and an equipotential device thereof, energy storage equipment and a power station, and under the condition that the equipotential device is arranged between a positive direct current bus and a negative direct current bus of the energy storage system, the potential (or potential) of an equipotential node in the equipotential device is between the voltage of the positive direct current bus and the voltage of the negative direct current bus of the energy storage system. Therefore, the voltage between the bus and the metal part connected with the equipotential node in the energy storage system can be effectively reduced, so that the reduced voltage is located between the positive direct current bus voltage and the negative direct current bus voltage, and the internal insulation design requirement of the energy storage system is effectively reduced.

Description

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

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the international patent application "Energy storage system and its equipotential device, energy storage equipment, and power station" with application number: PCT / CN2022 / 134399 and application date of November 25, 2022, and claims the priority of the international patent application. The entire content of the international patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the field of batteries, and specifically to an energy storage system and its equipotential device, energy storage equipment, and power station. Background Art

[0004] In related technologies, the power modules of energy storage systems are connected in parallel with multiple battery modules. To prevent damage to components in the energy storage system due to floating potential discharge in a high-voltage environment, the power modules are connected to the negative electrode at the same potential. However, the battery modules and other electronic components connected in parallel with the power modules in the energy storage system are also exposed to high voltage, but there is no effective protection measure.

[0005] Summary of the Invention

[0006] In view of the above problems, the present application provides an energy storage system and its equipotential device, energy storage equipment, and power station, which can solve the problem of high requirements for internal insulation design in energy storage systems in related technologies.

[0007] In a first aspect, an equipotential device is provided, which is applied to an energy storage system. The equipotential device includes an equipotential node. When the equipotential device is arranged between the positive DC bus and the negative DC bus of the energy storage system, the potential of the equipotential node is between the positive DC bus voltage and the negative DC bus voltage of the energy storage system.

[0008] When the equipotential device provided in the embodiments of the present disclosure is installed between the positive and negative DC busbars of an energy storage system, the potential of the equipotential node in the equipotential device is between the positive and negative DC busbar voltages of the energy storage system. This effectively reduces the voltage between the metal components connecting the busbars and the equipotential node in the energy storage system, placing the reduced voltage between the positive and negative DC busbar voltages, thereby effectively reducing the insulation design requirements within the energy storage system.

[0009] Optionally, the equipotential device includes a plurality of voltage dividing elements, the plurality of voltage dividing elements are connected in series, and the equipotential node is arranged between the plurality of voltage dividing elements, thereby achieving voltage division.

[0010] Optionally, the voltage dividing element includes a resistor.

[0011] Optionally, the plurality of voltage dividing elements include two resistors.

[0012] Optionally, the resistance values ​​of the two resistors are equal. Compared with the case where the two resistance values ​​are unequal, the equipotential effect of the equipotential device is better when the two resistance values ​​are equal.

[0013] 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.

[0014] Optionally, the equipotential device includes a first connection end and a second connection end, the first connection end is suitable for connecting to the positive DC bus, and the second connection end is suitable for connecting to the negative DC bus.

[0015] Optionally, the equipotential device further includes a capacitor, wherein,

[0016] The capacitor is connected between the equipotential node and the first connection terminal; or

[0017] The capacitor is connected between the equipotential node and the second connection terminal.

[0018] Optionally, when there are two capacitors, one of the two capacitors is connected between the equipotential node and the first connection terminal, and the other of the two capacitors is connected between the equipotential node and the second connection terminal.

[0019] In the disclosed embodiment, the resistor in the equipotential device may be connected in parallel with the capacitor or not. Compared to the case where the resistor is not connected in parallel with the capacitor, the equipotential effect of the equipotential device is better when the resistor is connected in parallel with the capacitor. In addition, compared to the case where the capacitor is connected in parallel with the voltage divider element located between the equipotential node and the positive DC bus, the equipotential effect of the equipotential device is better when the capacitor is connected in parallel with the voltage divider element located between the equipotential node and the negative DC bus. When there are two capacitors, the equipotential effect of the equipotential device is better when the capacitance values ​​of the two capacitors are equal than when the capacitance values ​​of the two capacitors are unequal.

[0020] Optionally, the capacitor is a Y capacitor.

[0021] Optionally, the capacitor may be a Y capacitor. Since the capacitor is connected in parallel with the resistor, if a surge occurs in the energy storage system, the capacitor is turned on, which can effectively prevent the problem of the potential of the equipotential node floating due to the surge.

[0022] Moreover, compared with the case where the capacitor is connected in parallel with the voltage divider element located between the equipotential node and the positive DC bus, the capacitor is connected in parallel with the voltage divider element located between the equipotential node and the negative DC bus, which matches the equipotential of the negative pole of the power unit. The voltage difference between the energy storage device and the power unit is small, and therefore the insulation risk is smaller.

[0023] Optionally, the equipotential node is suitable for connection to metal components in the energy storage system, thereby effectively reducing the voltage between the metal components and the busbar, further effectively reducing the internal insulation design requirements of the energy storage system, and effectively avoiding the risk of single-point insulation failure.

[0024] Optionally, the metal parts include one or more of the following: the shell of the electrical cabinet, the shell of the electrical box, the shell of the main control box, the shell of the battery, the shell of the control device, the grounding terminal of the control device, the shell of the relay, the shell of the power module, the shell of the electrical converter and the water cooling plate.

[0025] Optionally, the equipotential point is connected to the metal component by means of a wire, welding or bolt locking.

[0026] In a second aspect, an energy storage system is provided, comprising:

[0027] The power unit is configured to convert AC power and provide it to the positive and negative DC bus bars, or to transmit electrical energy;

[0028] The equipotential device described in the above aspect is provided between the positive and negative DC busbars and includes an equipotential node;

[0029] The energy storage device is connected in parallel between the positive and negative DC busbars, and the metal parts of the energy storage device are connected to the equipotential node.

[0030] Optionally, the energy storage device includes an electrical cabinet and at least one battery arranged in the electrical cabinet, the battery is connected between the positive and negative DC bus bars, and the metal component includes a shell of the electrical cabinet, thereby achieving the same potential as the shell of the electrical cabinet and the equipotential node.

[0031] Optionally, the energy storage device further includes an electrical box corresponding to each battery, the electrical box is arranged in the electrical cabinet, and the shell of the electrical box is connected to the shell of the electrical cabinet, thereby achieving the same potential as the shell of the electrical box and the equipotential node.

[0032] Optionally, the energy storage device further includes a main control box, and the shell of the main control box is connected to the shell of the electrical cabinet, thereby achieving equipotentiality between the shell of the main control box and the equipotential node.

[0033] Optionally, the equipotential device is arranged in the main control box.

[0034] Optionally, the main control box is also provided with a main positive switch, a main negative switch, a pre-charge switch and a pre-charge resistor. The main positive switch is connected in series with the positive DC bus in the positive and negative DC bus. After the pre-charge switch and the pre-charge resistor are connected in series, they are connected in parallel with the main positive switch. The main negative switch is connected in series with the negative DC bus in the positive and negative DC bus. One end of the equipotential device is connected between the main positive switch and the positive pole of the battery, and the other end of the equipotential device is connected between the main negative switch and the negative pole of the battery.

[0035] Optionally, the main control box is arranged outside the electrical cabinet, or the main control box is arranged inside the electrical cabinet.

[0036] Optionally, the equipotential device is arranged in the electrical cabinet, and one end of the equipotential device is connected to the positive electrode of the battery, and the other end of the equipotential device is connected to the negative electrode of the battery.

[0037] Optionally, when there are multiple batteries, the multiple batteries are connected in series.

[0038] Optionally, when there are multiple energy storage devices, multiple equipotential devices are provided, each connected in parallel between the positive and negative DC busbars, with the metal components of each energy storage device connected to an equipotential node configured for the corresponding equipotential device. The equipotential device is provided in each energy storage device, and all metal components in each energy storage device are at the same potential as the equipotential node. Furthermore, this implementation method can adapt to the insulation detection function of multiple parallel energy storage devices.

[0039] Optionally, when there are multiple energy storage devices, they are connected in parallel between the positive and negative DC busbars, and the metal components of any one of the multiple energy storage devices are connected to an equipotential node. The metal components of the multiple energy storage devices are connected in series. Each energy storage device is at the same potential as the equipotential node. This implementation is relatively simple to design. Furthermore, for applications where multiple electrical cabinets are centrally located in a single container (such as a container), the potential distribution within the container is relatively uniform, thus avoiding insulation issues.

[0040] Optionally, the power unit is arranged in a power box, and a shell of the power box is connected to the negative DC bus of the positive and negative DC bus bars.

[0041] Optionally, the power unit is configured by power devices into a half-bridge circuit, a full-bridge circuit or an energy storage converter.

[0042] Optionally, a bypass switch is provided at the input end of the power unit.

[0043] In a third aspect, an energy storage device is provided, comprising the energy storage system described in the above aspects.

[0044] Optionally, there are multiple energy storage systems, and the multiple energy storage systems are cascaded.

[0045] In a fourth aspect, a power station is provided, comprising the energy storage device described in the above aspects.

[0046] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a schematic structural diagram of an equipotential device provided by an embodiment of the present disclosure;

[0048] FIG2 is a schematic structural diagram of another equipotential device provided in an embodiment of the present disclosure;

[0049] FIG3 is a schematic structural diagram of another equipotential device provided in an embodiment of the present disclosure;

[0050] FIG4 is a schematic structural diagram of another equipotential device provided in an embodiment of the present disclosure;

[0051] FIG5 is a schematic structural diagram of an energy storage system provided by an embodiment of the present disclosure;

[0052] FIG6 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0053] FIG7 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0054] FIG8 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0055] FIG9 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0056] FIG10 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0057] FIG11 is a schematic structural diagram of another energy storage system provided by an embodiment of the present disclosure;

[0058] FIG12 is a schematic structural diagram of an energy storage device provided by an embodiment of the present disclosure;

[0059] FIG13 is a schematic structural diagram of another energy storage device provided in an embodiment of the present disclosure;

[0060] FIG14 is a schematic structural diagram of another energy storage device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0061] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be construed as limiting the present disclosure.

[0062] The power module of a traditional energy storage system is connected in series with a battery module. If the system voltage level is low, for example, the system voltage level is below 1500 volts (V), the housing of the battery module is generally directly grounded, and the high-voltage circuit and the housing of the battery module only need to meet the insulation withstand voltage requirements under the corresponding voltage level. For high-voltage direct current transmission and distribution systems, since the system voltage level is very high, for example, the system voltage level can reach tens of kilovolts or even hundreds of kilovolts, the housing of the power module in the energy storage system cannot be directly grounded, and high-voltage support insulators are generally used to support the power module. However, in order to prevent the primary and secondary components of the energy storage system from being damaged by floating potential discharge in a high-voltage environment, the housing of the power module still needs to be clamped, usually using a negative pole equipotential method, that is, the housing of the power module is connected to the negative pole.

[0063] The new high-voltage energy storage system in the related art includes a power module connected in parallel with multiple battery modules, and the power module and the negative electrode are at the same potential. For the new high-voltage energy storage system, if the battery modules connected in parallel with the power module also adopt the same negative electrode potential, the following problems will arise:

[0064] First, the battery module has a high risk of single-point insulation failure. Since the negative terminal is connected to the metal casing (equivalent to 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 terminals of the battery module, posing an extremely high safety risk.

[0065] Second, connecting the negative terminal to the chassis affects the battery module's insulation detection function. This insulation detection function requires that the voltage across the battery cannot be directly measured; in this case, the calculated insulation resistance value is 0. Furthermore, if the battery module consists of multiple parallel battery packs, each of which is equivalent to the same potential, the insulation detection function will interfere with each other.

[0066] Third, the voltage between the electrical box housing and the battery housing is higher, which means the voltage of the entire energy storage system is higher. When the electrical box housing is at the same potential as the negative pole of the busbar, the maximum voltage difference between it and the battery housing is the voltage of the entire battery module, resulting in a higher voltage between the electrical box housing and the battery housing.

[0067] FIG1 is a schematic diagram of the structure of an equipotential device provided by an embodiment of the present disclosure. The equipotential device 10 can be applied to an energy storage system. The equipotential device 10 can include an equipotential node. When the equipotential device 10 is disposed between the positive DC bus D+ and the negative DC bus D- of the energy storage system, the potential of the equipotential node is between the voltage of the positive DC bus D+ and the voltage of the negative DC bus D- of the energy storage system. This can effectively reduce the voltage between the metal components connecting the busbars and the equipotential node in the energy storage system, so that the reduced voltage is between the voltage of the positive DC bus D+ and the voltage of the negative DC bus D-, thereby effectively reducing the internal insulation design requirements of the energy storage system.

[0068] In summary, the disclosed embodiments provide an equipotential device. When the equipotential device is installed between the positive and negative DC busbars of an energy storage system, the potential of the equipotential node in the equipotential device is between the positive and negative DC busbar voltages of the energy storage system. This effectively reduces the voltage between the busbars in the energy storage system and the metal components connected to the equipotential node, placing the reduced voltage between the positive and negative DC busbar voltages, thereby effectively reducing the insulation design requirements within the energy storage system.

[0069] In the embodiment of the present disclosure, the equipotential device 10 may include multiple voltage-dividing elements, which are connected in series, and the equipotential node K is arranged between the multiple voltage-dividing elements. Optionally, the equipotential node K may be the midpoint of the multiple voltage-dividing elements.

[0070] 2 , each voltage dividing element may include a resistor, and the voltage dividing element may include one or more resistors. If the voltage dividing element includes multiple resistors, the multiple resistors may be connected in series and / or in parallel.

[0071] Optionally, the resistance between the equipotential node K and the positive DC bus D+ can be equal to the resistance between the equipotential node K and the negative DC bus D−, thereby effectively reducing the internal insulation design requirements of the energy storage system. That is, the sum of the resistances of the resistors between the equipotential node K and the positive DC bus D+ is equal to the sum of the resistances of the resistors between the equipotential node K and the negative DC bus D−.

[0072] Optionally, the plurality of voltage divider elements may include two resistors connected in series, and the two resistors are further adapted to connect the positive DC bus D+ and the negative DC bus D-. The equipotential node K may be disposed between the two resistors. For example, referring to FIG2 , the equipotential node K may be disposed at the midpoint of the two resistors (i.e., the first resistor R1 and the second resistor R2).

[0073] Optionally, the resistance values ​​of the two resistors may be equal or unequal. It is understood that the equal resistance values ​​of the two resistors may mean that the two resistance values ​​are absolutely equal or approximately equal. Absolute equality means that the difference between the two resistance values ​​is 0, and approximately equality means that the absolute value of the difference between the two resistance values ​​is less than a first difference threshold, and the first difference threshold is greater than 0.

[0074] In the embodiment of the present disclosure, compared with the case where the two resistance values ​​are unequal, if the equipotential node K is set at the midpoint of the two resistors, the voltage between the metal component and the busbar in the energy storage system can be reduced by half, and the equipotential effect of the equipotential device 10 is better.

[0075] Referring to Figures 3 and 4 , the equipotential device 10 may include a first connection terminal u1 and a second connection terminal u2. The first connection terminal u1 is adapted to connect to the positive DC bus D+, and the second connection terminal u2 is adapted to connect to the negative DC bus D-. The first connection terminal u1 is also connected to one end of a plurality of voltage divider elements, and the second connection terminal u2 is also connected to the other ends of the plurality of voltage divider elements. For example, referring to Figures 3 and 4 , the first connection terminal u1 is also connected to the first resistor R1, and the second connection terminal u2 is also connected to the second resistor R2.

[0076] The equipotential device 10 may further include a capacitor C1 connected between the equipotential node K and the first connection terminal u1. Specifically, the capacitor C1 is connected in parallel with a voltage divider between the positive DC bus D+ and the equipotential node K. For example, referring to FIG3 , the capacitor C1 is connected in parallel with a first resistor R1. Alternatively, the capacitor C1 is connected between the equipotential node K and the second connection terminal u2. Specifically, the capacitor C1 is connected in parallel with a voltage divider between the negative DC bus D− and the equipotential node K. For example, referring to FIG4 , the capacitor C1 is connected in parallel with a second resistor R2.

[0077] When there are two capacitors C1, one of the two capacitors C1 is connected between the equipotential node K and the first connection terminal u1, and the other of the two capacitors C1 is connected between the equipotential node K and the second connection terminal u2. That is, one of the two capacitors C1 is connected in parallel with the voltage divider element located between the positive DC bus D+ and the equipotential node K, and the other is connected in parallel with the voltage divider element located between the negative DC bus D- and the equipotential node K.

[0078] When there are two capacitors, the capacitances of the two capacitors may be equal or unequal. It is understood that the equal capacitances of the two capacitors may mean that the two capacitances are absolutely equal or approximately equal. Absolute equality means that the difference between the two capacitances is 0, and approximately equality means that the absolute value of the difference between the two capacitances is less than a second difference threshold, and the second difference threshold is greater than 0.

[0079] Compared with the case where the two capacitances are unequal, the equipotential effect of the equipotential device 10 is better when the two capacitances are equal.

[0080] In the embodiment of the present disclosure, the voltage divider element in the equipotential device 10 may be connected in parallel with the capacitor C1 or not. Compared with the case where the voltage divider element is connected in parallel with the capacitor C1, the equipotential effect of the equipotential device is better.

[0081] Optionally, the capacitor C1 may be a Y capacitor. Since the capacitor C1 is a Y capacitor and is connected in parallel with the voltage divider, if a surge occurs in the energy storage system, the capacitor C1 is turned on, which can effectively prevent the potential of the equipotential node from floating due to the surge.

[0082] Moreover, compared to the case where the capacitor C1 is connected in parallel with the voltage divider element located between the positive DC bus D+ and the equipotential node K, the case where the capacitor C1 is connected in parallel with the voltage divider element located between the negative DC bus D- and the equipotential node K is more compatible with the equipotential mode of the negative pole of the power unit, and the voltage difference between the energy storage device and the power unit is small, so the insulation risk is smaller.

[0083] In the disclosed embodiment, the equipotential node K is also suitable for connection to metal components in the energy storage system, thereby effectively reducing the voltage between the metal component and the busbar, further effectively reducing the insulation design requirements within the energy storage system. Furthermore, if the equipotential node K is the midpoint of multiple voltage divider elements, and the resistance between the equipotential node K and the positive DC busbar D+ is equal to the resistance between the equipotential node K and the negative DC busbar D-, the voltage between the metal component and the busbar can be reduced by half, further effectively reducing the insulation design requirements within the energy storage system.

[0084] Furthermore, the equipotential point K can be connected to the metal component by means of a wire, welding or bolt locking. The metal component may include one or more of the following: the housing of the electrical cabinet, the housing of the electrical box, the housing of the main control box, the housing of the battery, the housing of the control device, the ground terminal of the control device, the housing of the relay, the housing of the power module, the housing of the electrical converter and the water-cooling plate. The control device can be used to control charging and discharging, the power module is used to convert alternating current, and the electrical converter can be a device such as direct current / alternating current (DC / AC), AC / DC or DC / DC. Furthermore, the metal component is connected to the equipotential point K, which can effectively avoid the risk of single-point insulation failure.

[0085] Optionally, the metal component may include a housing of an electronic device, that is, the equipotential node K is also suitable for connecting to the housing of an electronic device in the energy storage system. Optionally, the housing of the electronic device may include one or more of the following: a housing of an electrical cabinet, a housing of an electrical box, a housing of a main control box, a housing of a battery, a housing of a control device, a housing of a relay, a housing of a power module, and a housing of an electrical converter.

[0086] In summary, the disclosed embodiments provide an equipotential device. When the equipotential device is installed between the positive and negative DC busbars of an energy storage system, the potential of the equipotential node in the equipotential device is between the positive and negative DC busbar voltages of the energy storage system. This effectively reduces the voltage between the busbars in the energy storage system and the metal components connected to the equipotential node, placing the reduced voltage between the positive and negative DC busbar voltages, thereby effectively reducing the insulation design requirements within the energy storage system.

[0087] FIG5 is a schematic structural diagram of an energy storage system provided by an embodiment of the present disclosure. As shown in FIG5 , the energy storage system 100 may include a power unit 20 , an equipotential device 10 , and an energy storage device 30 .

[0088] The power unit 20 is configured to convert alternating current and provide it to positive and negative direct current buses, or to transmit electrical energy.

[0089] The equipotential device 10 is disposed between the positive and negative DC busbars and includes an equipotential node.

[0090] The energy storage device 30 is connected in parallel between the positive and negative DC busbars, and the metal components of the energy storage device 30 are connected to the equipotential node.

[0091] Optionally, there may be multiple energy storage devices 30 , and the multiple energy storage devices 30 are connected in parallel between the positive and negative DC bus bars, and the metal components of the energy storage devices are connected to the equipotential node K.

[0092] In summary, the disclosed embodiments provide an energy storage system in which an equipotential device is disposed between the positive and negative DC busbars of the energy storage system. The potential of the equipotential node in the equipotential device is between the positive and negative DC busbar voltages of the energy storage system. This effectively reduces the voltage between the busbars in the energy storage system and the metal components connected to the equipotential node, placing the reduced voltage between the positive and negative DC busbar voltages, thereby effectively lowering the insulation design requirements within the energy storage system.

[0093] Referring to Figures 6, 7, and 8, the energy storage device 30 may include an electrical cabinet 31 and at least one battery B disposed in the electrical cabinet 31. When multiple batteries B are disposed in the electrical cabinet 31, the multiple batteries B are connected in series. Figures 6 to 8 illustrate an example in which the energy storage device 30 includes two batteries B, and the two batteries B are connected in series. The battery B is connected between the positive and negative DC busbars. The metal component may include the housing 31a of the electrical cabinet 31, that is, the housing 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.

[0094] Referring to Figures 6 to 8, the energy storage device 30 may further include an electrical box 32 corresponding to each battery B. The electrical box 32 is disposed within the electrical cabinet 31, and the housing 32a of the electrical box 32 is connected to the housing 31a of the electrical cabinet 31. Since the housing 31a of the electrical cabinet 31 is connected to the equipotential node K, and the housing 32a of each electrical box 32 is connected to the housing 31a of the electrical cabinet 31, the housing 32a of each electrical box 32 is also connected to the equipotential node, that is, the metal component may also include the housing 32a of each electrical box 32. This can effectively reduce the voltage between the battery B and the housing 31a of the electrical cabinet 31, further effectively reducing the internal insulation design requirements of the energy storage system. If the equipotential node K is the midpoint of the first resistor and the second resistor of at least two resistors, and 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-, the voltage between the battery B and the shell 31a of the electrical cabinet 31 can be reduced by half, further effectively reducing the internal insulation design requirements of the energy storage system.

[0095] With reference to Figures 7 and 8 , the energy storage device 30 may further include a main control box 33, whose housing 33a is connected to the housing 31a of the electrical cabinet 31. Because the housing 31a of the electrical cabinet 31 is connected to the equipotential node K, and the housing 33a of the main control box 33 is also connected to the housing 31a of the electrical cabinet 31, the housing 33a of the main control box 33 is also connected to the equipotential node K. This means that the metal component may also include the housing 33a of the main control box 33, effectively reducing the internal insulation design requirements of the energy storage system.

[0096] In an optional implementation of the embodiment of the present disclosure, referring to Figures 6 and 7, the equipotential device 10 can be set in the main control box 33, and the main control box 33 can also be provided with a main positive switch S1, a main negative switch S2, a pre-charge switch S3 and a pre-charge resistor r.

[0097] The main positive switch S1 is connected in series with the positive DC bus D+. The pre-charge switch S3 and pre-charge resistor r are connected in series and then connected in parallel with the main positive switch S1. That is, the pre-charge switch S3 and pre-charge resistor r, which are connected in series, are connected in parallel with the main positive switch S1. The main negative switch S2 is also connected in series with the negative DC bus D-. One end of the equipotential device 10 is connected between the main positive switch S1 and the positive electrode of battery B, and the other end of the equipotential device 10 is connected between the main negative switch S2 and the negative electrode of battery B.

[0098] 6 and 7 , the first connection terminal u1 of the isopotential device 10 is connected between the main positive switch S1 and the positive electrode of the battery B, and the second connection terminal u2 of the isopotential device 10 is connected between the main negative switch S2 and the negative electrode of the battery B.

[0099] The equipotential node K is directly connected to the shell 33a of the main control box 33. Since the shell 33a of the main control box 33 is connected to the shell 31a of the electrical cabinet 31, and the shell 31a of the electrical cabinet 31 is connected to the shell 32a of each electrical box 32, the equipotential node K is connected to the shell 33a of the main control box 33, the shell 31a of the electrical cabinet 31 and the shell of each electrical box 32.

[0100] In the embodiment of the present disclosure, the main control box 33 can be set in the electric cabinet 31, or as shown in Figures 6 and 7, the main control box 33 can be set outside the electric cabinet 31.

[0101] 6 and 7 , the main control box may further include two fuses F, one fuse F being connected in series with the main positive switch S1 , and the other fuse F being connected in series with the main negative switch S2 .

[0102] In another optional implementation of the embodiment of the present disclosure, referring to Figure 8, the equipotential device 10 can be set in the electrical cabinet 31, and one end of the equipotential device 10 is connected to the positive pole of battery B, and the other end of the equipotential device 10 is connected to the negative pole of battery B.

[0103] Optionally, the first connection terminal u1 in the equipotential device 10 is connected to the positive electrode of battery B, and the second connection terminal u2 is connected to the negative electrode of battery B.

[0104] The equipotential node K is directly connected to the shell 31a of the electrical cabinet 31. Since the shell 33a of the main control box 33 is connected to the shell 31a of the electrical cabinet 31, and the shell 31a of the electrical cabinet 31 is connected to the shell 32a of each electrical box 32, the equipotential node K is connected to the shell 33a of the main control box 33, the shell 31a of the electrical cabinet 31 and the shell of each electrical box 32.

[0105] When there are multiple energy storage devices 30, in an optional implementation of the present disclosure, referring to FIG9 , there may be multiple equipotential devices 10, each corresponding one-to-one to each of the multiple energy storage devices 30. The multiple energy storage devices 30 are connected in parallel between the positive and negative DC busbars, and the metal component of each energy storage device 30 (e.g., the housing 33a of the main control box 33) is connected to the equipotential node K configured for the corresponding equipotential device 10. FIG8 illustrates the example of two energy storage devices 30 connected in parallel between the positive and negative DC busbars.

[0106] In this case, each energy storage device 30 is provided with an equipotential device 10. As shown in Figures 6 to 8, if the main control box 33 is located inside the electrical cabinet 31, the equipotential device 10 can be located inside the main control box 33 or between the main control box 33 and the electrical cabinet 32. If the main control box 33 is located outside the electrical cabinet 31, the equipotential device 10 can be located inside the main control box 33 or inside the electrical cabinet 31. This disclosure is not limited to this.

[0107] In this implementation, the equipotential device is provided in each energy storage device, and the metal components in each energy storage device are at the same potential as the equipotential node K. Furthermore, this implementation can adapt to the insulation detection function of multiple energy storage devices connected in parallel.

[0108] In another optional implementation of the embodiment of the present disclosure, referring to Figure 10, the multiple energy storage devices 30 are respectively connected in parallel between the positive and negative DC bus bars, and the metal components of any one of the multiple energy storage devices 30 (for example, the shell 33a of the main control box 33) are connected to the equipotential node K, and the metal components of the multiple energy storage devices 30 (for example, the shell 33a of the main control box 33) are connected in series.

[0109] In the embodiment of the present disclosure, the power unit 20 may be disposed in a power box 40 , and a housing 40 a of the power box 40 is connected to the negative DC bus D− of the positive and negative DC buses.

[0110] In this implementation, each energy storage device is at the same potential as the equipotential node K. The design of this implementation is relatively simple. At the same time, for application scenarios where multiple electrical cabinets are concentrated in one cabin (such as a container), the potential distribution in the container is also relatively simple, which can avoid insulation problems.

[0111] 9 to 10 , a bypass switch S4 is provided at the input end of the power unit 20 . The bypass switch S4 is used to be turned off when a fault occurs in the energy storage system and to be turned on when the energy storage system operates normally.

[0112] 9 and 10 , the power unit 20 may be configured as a half-bridge circuit using power devices, which may include a first power switch S5, a second power switch S6, an energy storage capacitor C2, and a voltage divider 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 divider 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 divider resistor R3, and the negative DC bus D−, respectively.

[0113] Alternatively, referring to FIG11 , the power unit 20 may be configured as a full-bridge circuit by 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 .

[0114] 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 divider resistor R3, and the positive DC bus D+. 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 divider 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.

[0115] Alternatively, the power unit 20 may be configured as a power conversion system (PCS) by means of power devices.

[0116] In summary, the disclosed embodiments provide an energy storage system in which an equipotential device is disposed between the positive and negative DC busbars of the energy storage system. The potential of the equipotential node in the equipotential device is between the positive and negative DC busbar voltages of the energy storage system. This effectively reduces the voltage between the metal components connecting the busbars and the equipotential node in the energy storage system, placing the reduced voltage between the positive and negative DC busbar voltages, thereby effectively lowering the insulation design requirements within the energy storage system.

[0117] An embodiment of the present disclosure provides an energy storage device, which may include the energy storage system described in the above embodiment, for example, the energy storage system shown in any one of Figures 5 to 11.

[0118] 12 to 14 , there are multiple energy storage systems 100 , and the multiple energy storage systems 100 are connected in cascade.

[0119] Referring to Figure 12, the energy storage device 1000 can be a direct-current energy storage device, which can be used to achieve functions such as power output and energy storage based on the direct current transmitted by the positive and negative DC bus. Referring to Figure 12, the energy storage device 1000 can also include an isolation switch M, a starting resistor R4, a starting switch S9, and a first inductor L1. The starting resistor R4 is used to protect the energy storage device 1000 during the startup process of the energy storage device. Among them, one end of the isolation switch M is connected to the positive DC bus P+, and the other end of the isolation switch M is respectively connected to one end of the starting resistor R4 and one end of the starting switch S9. The other end of the starting resistor R4 and the other end of the starting switch S9 are both connected to one end of the first inductor L1, and the other end of the first inductor L1 is connected to one end of multiple cascade-connected energy storage systems 100, and the other end of the multiple cascade-connected energy storage systems 100 is connected to the negative DC bus P-. In this implementation, the power unit in the energy storage system is used to transmit direct current.

[0120] Referring to Figure 13, the energy storage device 1000 can also be a modular multi-level energy storage device, which can realize functions such as AC-DC conversion and control of active or reactive output. Referring to Figure 13, the energy storage device 1000 may include six commutation bridge arms, each of which may include multiple cascade-connected energy storage systems 100 and second inductors L2. One end of the second inductor L2 in each commutation bridge arm is connected to the AC bus X, and the other end of the second inductor L2 in each commutation bridge arm is connected to one end of the multiple cascade-connected energy storage systems 100, and the other end of the multiple cascade-connected energy storage systems 100 is connected to the DC bus W. The energy storage device 1000 is used to convert the DC power transmitted by the DC bus W into AC power and transmit it to the power-consuming equipment through the AC bus X.

[0121] Referring to FIG14 , the energy storage device 1000 can also be a cascade energy storage device, capable of implementing functions such as power output and energy storage based on the AC power transmitted by the received AC bus. The energy storage device 1000 can include three commutation bridge arms, each of which can include a third reactor L3 and multiple cascade-connected energy storage systems 100. One end of the third reactor L3 in each commutation bridge arm is connected to the AC bus X, and the other end of the third reactor L3 in each commutation bridge arm is connected to one end of the multiple cascade-connected energy storage systems 100. The other ends of the multiple cascade-connected energy storage systems 100 included in the three commutation bridge arms are connected to each other.

[0122] An embodiment of the present disclosure provides a power station, which may include the energy storage device described in the above embodiment, for example, the energy storage device 1000 shown in Figures 12 to 14 above.

[0123] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device), or in conjunction with such instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by an instruction execution system, apparatus, or device, or in conjunction with such instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion having one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or processing in other suitable ways as necessary, and then stored in a computer memory. It should be understood that the various parts of the present disclosure may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof may be used to implement it: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0124] In the description of this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In the description of the present disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present disclosure and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present disclosure.

[0125] In addition, the terms "first" and "second" used in the embodiments of the present disclosure are only used for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features indicated in the embodiments. Therefore, the features defined in the embodiments of the present disclosure with terms such as "first" and "second" can explicitly or implicitly indicate that the embodiment includes at least one such feature. In the description of the present disclosure, the word "plurality" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0126] In this disclosure, unless otherwise specified or limited in the embodiments, the terms "mounted," "connected," "connect," and "fixed" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a removable connection, or an integral connection. It can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, an indirect connection through an intermediate medium, or internal communication between two components, or an interaction between two components. A person skilled in the art will be able to understand the specific meanings of the above terms in this disclosure based on specific implementations. In this disclosure, unless otherwise specified or limited, a first feature being "above" or "below" a second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0127] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. An equipotential device, characterized in that: Applied to an energy storage system, the equipotential device includes an equipotential node. When the equipotential device is arranged between the positive DC bus and the negative DC bus of the energy storage system, the potential of the equipotential node is between the positive DC bus voltage and the negative DC bus voltage of the energy storage system.

2. The equipotential device according to claim 1, characterized in that: The equipotential device includes a plurality of voltage dividing elements, the plurality of voltage dividing elements are connected in series, and the equipotential node is arranged between the plurality of voltage dividing elements.

3. The equipotential device according to claim 2, characterized in that: The voltage dividing element includes a resistor.

4. The equipotential device according to claim 3, characterized in that: The plurality of voltage dividing elements include two resistors.

5. The equipotential device according to claim 4, characterized in that: The resistance values ​​of the two resistors are equal.

6. The equipotential device according to claim 3, characterized in that: 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.

7. The equipotential device according to any one of claims 1 to 6, characterized in that: The equipotential device includes a first connection end and a second connection end. The first connection end is suitable for connecting to the positive DC bus, and the second connection end is suitable for connecting to the negative DC bus.

8. The equipotential device according to claim 7, characterized in that: The equipotential 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.

9. The equipotential device according to claim 8, characterized in that: 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. The equipotential device according to claim 8, characterized in that: The capacitor is a Y capacitor.

11. The equipotential device according to any one of claims 1 to 10, characterized in that: The equipotential node is suitable for connecting to a metal component in the energy storage system.

12. The equipotential device according to claim 11, characterized in that: The metal parts include one or more of the following: the shell of the electrical cabinet, the shell of the electrical box, the shell of the main control box, the shell of the battery, the shell of the control device, the grounding terminal of the control device, the shell of the relay, the shell of the power module, the shell of the electrical converter and the water cooling plate.

13. The equipotential device according to claim 11, characterized in that: The equipotential point is connected to the metal component by means of a wire, welding or bolt locking.

14. An energy storage system, characterized in that: include: A power unit configured to convert alternating current and provide it to positive and negative direct current buses, or to transmit electrical energy; The equipotential device according to any one of claims 1 to 13, wherein the equipotential device is arranged between the positive and negative DC busbars and comprises an equipotential node; An energy storage device is connected in parallel between the positive and negative DC bus bars, and a metal component of the energy storage device is connected to the equipotential node.

15. The energy storage system according to claim 14, characterized in that: The energy storage device includes an electrical cabinet and at least one battery arranged in the electrical cabinet, the battery is connected between the positive and negative DC busbars, and the metal component includes a shell of the electrical cabinet.

16. The energy storage system according to claim 15, characterized in that: The energy storage device further includes an electrical box corresponding to each of the batteries. The electrical box is disposed in the electrical cabinet, and a shell of the electrical box is connected to a shell of the electrical cabinet.

17. The energy storage system according to claim 15, characterized in that: The energy storage device further includes a main control box, and a shell of the main control box is connected to the shell of the electric cabinet.

18. The energy storage system according to claim 17, characterized in that: The equipotential device is arranged in the main control box.

19. The energy storage system according to claim 18, characterized in that: The main control box is also provided with a main positive switch, a main negative switch, a pre-charge switch and a pre-charge resistor. The main positive switch is connected in series with the positive DC bus of the positive and negative DC busbars. After the pre-charge switch and the pre-charge resistor are connected in series, they are connected in parallel with the main positive switch. The main negative switch is connected in series with the negative DC bus of the positive and negative DC busbars. One end of the equipotential device is connected between the main positive switch and the positive pole of the battery, and the other end of the equipotential device is connected between the main negative switch and the negative pole of the battery.

20. The energy storage system according to claim 18, characterized in that The main control box is arranged outside the electric cabinet, or the main control box is arranged inside the electric cabinet.

21. The energy storage system according to claim 15, characterized in that The equipotential device is arranged in the electric cabinet, and one end of the equipotential device is connected to the positive electrode of the battery, and the other end of the equipotential device is connected to the negative electrode of the battery.

22. The energy storage system according to any one of claims 15 to 21, characterized in that: When there are a plurality of batteries, the plurality of batteries are connected in series.

23. The energy storage system according to any one of claims 14 to 22, characterized in that: When there are multiple energy storage devices, there are multiple equipotential devices, and the multiple energy storage devices are connected in parallel between the positive and negative DC busbars, and the metal component of each energy storage device is connected to the equipotential node configured by the corresponding equipotential device.

24. The energy storage system according to any one of claims 14 to 17, characterized in that: When there are multiple energy storage devices, the multiple energy storage devices are connected in parallel between the positive and negative DC bus bars, and the metal components of any one of the multiple energy storage devices are connected to the equipotential node, and the metal components of the multiple energy storage devices are connected in series.

25. The energy storage system according to any one of claims 14 to 24, characterized in that: The power unit is arranged in a power box, and a shell of the power box is connected to the negative DC bus of the positive and negative DC bus bars.

26. The energy storage system according to any one of claims 14 to 24, characterized in that: The power unit is configured by power devices into a half-bridge circuit, a full-bridge circuit or an energy storage converter.

27. The energy storage system according to any one of claims 14 to 24, characterized in that: The input end of the power unit is provided with a bypass switch.

28. An energy storage device, characterized in that: Comprising an energy storage system according to any one of claims 14-27.

29. The energy storage device according to claim 28, characterized in that There are multiple energy storage systems, and the multiple energy storage systems are connected in cascade.

30. A power station, characterized in that: Comprising an energy storage device according to claim 28 or 29.

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