A current collecting device of an energy storage system and a control method of an energy storage system

Abstract

The application discloses a current collecting device of an energy storage system and a control method of the energy storage system, and belongs to the technical field of the energy storage system. The device comprises N battery management modules; a target battery management module comprises a target direct-current control unit and a target power conversion unit; a detection board provided with a first control chip and a second control chip is used for acquiring operation parameters of a target battery cluster and performing regulation and control on the target direct-current control unit and the target power conversion unit through the first control chip and the second control chip respectively, so as to perform on-grid and off-grid control on the N battery clusters; and an alternating-current current collecting module is used for collecting the voltage output by the N battery management modules into a power grid. The device can solve the technical problems of poor safety, strong coupling interference between battery clusters, low availability of the energy storage system and poor expansion flexibility in the prior art when the multiple battery clusters in the energy storage system are subjected to current collection.

Description

Technical Field

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

[0002] Currently, when the output voltages of multiple battery clusters in an energy storage system are fed into the grid, they are typically connected in parallel on the DC side. That is, in the existing energy storage architecture, each battery cluster is connected to a high-voltage box via cables. Then, multiple high-voltage boxes centrally transmit the DC power output from each battery cluster to a PCS (Power Conversion System) through a combiner cabinet. Finally, a transformer connects the AC power output from the PCS to the grid through the high-voltage cabinet. However, in this energy storage architecture, because multiple battery clusters are connected in parallel at the DC bus, there are not only high safety risks, but also strong coupling interference between the battery clusters. Furthermore, the existing PCS only has one DC input port; if the PCS fails, all battery clusters in the energy storage system will be forced out of grid dispatch, greatly reducing the availability of the energy storage system. In addition, under this energy storage architecture, if you want to expand the battery cluster capacity, you must add a new PCS to the energy storage system or reconfigure the DC combiner bus, resulting in extremely poor flexibility in battery cluster expansion.

[0003] Therefore, how to better combine multiple battery clusters in an energy storage system and solve the above-mentioned problems are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a current-combining device for an energy storage system and a control method for an energy storage system, so as to solve the technical problems of poor safety, strong coupling interference between battery clusters, low availability of the energy storage system, and poor expansion flexibility in the prior art when combining multiple battery clusters in an energy storage system. The specific solution is as follows: To address the aforementioned technical problems, the present invention provides a combiner device for an energy storage system, comprising: N battery management modules are connected one-to-one with N battery clusters; the target battery management module is any one of the N battery management modules; the target battery management module includes: a target DC control unit for electrical protection of the target battery cluster and a target power conversion unit for AC conversion and current control of the output voltage of the target battery cluster; N≥2; A detection board equipped with a first control chip and a second control chip is connected to all N battery management modules. It is used to collect the operating parameters of the target battery clusters and to regulate the target DC control unit and the target power conversion unit through the first control chip and the second control chip, respectively, so as to control the grid connection and disconnection of the N battery clusters. An AC combiner module is connected to N battery management modules and the detection board, and is used to combine the voltage output by the N battery management modules into the power grid.

[0005] Preferably, the target DC control unit includes: a first filter module for filtering the output voltage of the target battery cluster, a circuit breaker, a DC fuse, a pre-charge resistor, a pre-charge relay, a positive relay, and a negative relay; In this configuration, the two output terminals of the first filter module are connected to the first and second terminals of the circuit breaker, respectively; the third terminal of the circuit breaker is connected to the first terminal of the negative relay; the second terminal of the negative relay is connected to the first input terminal of the target power conversion unit; the fourth terminal of the circuit breaker is connected to the first terminal of the DC fuse; the second terminal of the DC fuse is connected to the first terminal of the pre-charge resistor and the first terminal of the positive relay, respectively; the second terminal of the positive relay is connected to the second input terminal of the target power conversion unit; the second terminal of the pre-charge resistor is connected to the first terminal of the pre-charge relay; and the second terminal of the pre-charge relay is connected to the second input terminal of the target power conversion unit. The sampling control terminal of the first control chip is connected to the control terminal of the circuit breaker, the control terminal of the positive relay, the control terminal of the negative relay, and the control terminal of the precharge relay. The sampling control terminal of the first control chip is also connected to the current detector set at the third terminal of the circuit breaker.

[0006] Preferably, the target power conversion unit includes: a power board, a second filter module, a first contactor, a second contactor, a third contactor, a first fuse, a second fuse, and a third fuse; The first and second input terminals of the power board are connected to the second terminals of the negative relay and the positive relay, respectively. The first, second, and third output terminals of the power board are connected to the first, second, and third input terminals of the second filter module, respectively. The first, second, and third output terminals of the second filter module are connected to the first, second, and third terminals of the first contactor, the second contactor, and the third contactor, respectively. The second terminals of the first, second, and third contactors are connected to the first, second, and third fuses, respectively. The second terminals of the first, second, and third fuses are connected to the AC combiner module, respectively. The first terminal of the second control chip is connected to the control terminal of the power board. The second terminal of the second control chip is connected to the first output terminal, the second output terminal, and the third output terminal of the power board, respectively. The third terminal of the second control chip is connected to the control terminal of the second filter module. The fourth terminal of the second control chip is connected to the first output terminal, the second output terminal, and the third output terminal of the second filter module. The fifth terminal of the second control chip is connected to the first terminal of the first fuse, the first terminal of the second fuse, and the first terminal of the third fuse. The control terminal of the second control chip is connected to the control terminal of the first contactor, the control terminal of the second contactor, and the control terminal of the third contactor. Accordingly, the first input terminal and the second input terminal of the power board are respectively the first input terminal and the second input terminal of the target power conversion unit.

[0007] Preferred options also include: An isolation transformer is connected between the target DC control unit and the target power conversion unit to provide electrical isolation between the target battery cluster and the target power conversion unit.

[0008] Preferred options also include: A DC / AC converter is connected between the target DC control unit and the target power conversion unit to convert the output voltage of the target battery cluster.

[0009] To address the aforementioned technical problems, the present invention also provides a control method for an energy storage system, applied to a detection board in a combiner device of the aforementioned energy storage system, comprising: When N battery clusters in the energy storage system need to perform grid connection operations, the operating parameters of the target battery clusters are detected by the first control chip; the combiner device is installed in the energy storage system. When it is determined from the operating parameters of the target battery cluster that the connection lines of the target DC control unit are all normal and the target battery cluster meets the high voltage determination conditions, a pre-charge command is issued to the target battery cluster according to the grid connection command. When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is adjusted by the second control chip so that N battery clusters can perform grid connection operation. When N battery clusters need to perform off-grid operation, the target battery cluster is controlled to stop performing charging and discharging operations, and the target power conversion unit is controlled by the second control chip to perform power reduction operation. When the output power of the target power conversion unit is less than a first preset threshold, the line connection with the target battery cluster is disconnected, and the off-grid operation of N battery clusters is completed simultaneously.

[0010] Preferably, when it is determined from the operating parameters of the target battery cluster that the connection lines of the target DC control unit are all normal, and the target battery cluster meets the high-voltage determination condition, a pre-charge command is issued to the target battery cluster according to the grid connection command, and when the target battery cluster has completed pre-charging, the output voltage of the target power conversion unit is adjusted by the second control chip to enable N battery clusters to perform grid connection operation, including: When the target DC control unit includes: a first filter module for filtering the output voltage of the target battery cluster, a circuit breaker, a DC fuse, a pre-charge resistor, a pre-charge relay, a positive relay, and a negative relay; wherein, the two output terminals of the first filter module are respectively connected to the first and second terminals of the circuit breaker, the third terminal of the circuit breaker is connected to the first terminal of the negative relay, the second terminal of the negative relay is connected to the first input terminal of the target power conversion unit, the fourth terminal of the circuit breaker is connected to the first terminal of the DC fuse, the second terminal of the DC fuse is connected to the first terminal of the pre-charge resistor and the first terminal of the positive relay, the second terminal of the positive relay is connected to the second input terminal of the target power conversion unit, the second terminal of the pre-charge resistor is connected to the first terminal of the pre-charge relay, and the second terminal of the pre-charge relay is connected to the second input terminal of the target power conversion unit; Determine whether the circuit breaker is in the open state; If so, determine whether both the negative relay and the positive relay are functioning normally based on the operating parameters of the target battery cluster; If so, check whether the insulation resistance between the positive terminal of the target battery cluster and ground and the insulation resistance between the negative terminal of the target battery cluster and ground are both normal. If so, the target battery cluster is determined to meet the conditions for applying high voltage. When a grid connection command is received from the BAU or EMS in the energy storage system, it is determined whether the combiner cabinet in the energy storage system is in the closed state. If so, a pre-charge command is sent to the target battery cluster; When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is regulated by the second control chip; When the output voltage of the target power conversion unit is synchronized with the voltage of the power grid, the target power conversion unit is controlled to be connected to the power grid, and the grid connection operation of N battery clusters is completed synchronously.

[0011] Preferably, after determining whether the circuit breaker is in an open state, the method further includes: If not, disconnect the shunt trip unit in the circuit breaker; Accordingly, after determining whether both the negative relay and the positive relay are functioning normally based on the operating parameters of the target battery cluster, the process further includes: If not, continue with the step of disconnecting the shunt trip unit in the circuit breaker.

[0012] Preferably, the step of controlling the target battery cluster to stop performing charging and discharging operations, and controlling the target power conversion unit to perform a power reduction operation through the second control chip, so as to disconnect the line connection with the target battery cluster when the output power of the target power conversion unit is less than a first preset threshold, and simultaneously complete the off-grid operation of N battery clusters, including: Control the target battery cluster to stop performing charging and discharging operations; The second control chip controls the target power conversion unit to perform a power reduction operation, and after a first preset time delay, it is determined whether the output power of the target power conversion unit is less than the first preset threshold. If not, the target power conversion unit is determined to be faulty, and the shunt trip unit in the circuit breaker is disconnected; If so, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; If not, it is determined that the positive relay and / or the negative relay has a sticking fault, and the step of disconnecting the shunt trip unit in the circuit breaker is continued; If so, it is determined that the line connection with the target battery cluster has been disconnected, and the off-grid operation of N battery clusters is completed simultaneously.

[0013] Preferred options also include: Determine whether the energy storage system has triggered a preset alarm condition; If so, the target power conversion unit is controlled by the second control chip to perform a power reduction operation, and after a second preset time delay, it is determined whether the output power of the target power conversion unit is less than a second preset threshold. If not, disconnect the shunt trip unit in the circuit breaker and display the first warning message; If so, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; If not, it is determined that the positive relay and / or the negative relay has a sticking fault, and the shunt trip unit in the circuit breaker is disconnected, and a second warning message is issued; If so, the energy storage system is determined to have shut down, and a third warning message is issued.

[0014] Beneficial Effects: The current combiner device for an energy storage system provided by this invention comprises N battery management modules, a detection board, and an AC current combiner module. The N battery management modules are connected to the detection board, while the AC current combiner module is connected to both the N battery management modules and the detection board. The AC current combiner module can combine the AC voltage output from the N battery management modules into the power grid. If any one of the N battery management modules is named the target battery management module, it can be divided into a target DC control unit and a target power conversion unit. Since the target DC control unit provides electrical protection for the target battery cluster, combined with the control and management logic of the first control chip on the detection board, it is equivalent to allowing the first control chip to take over the logic management function of the BCU in the energy storage system. The target power conversion unit performs AC conversion and current conversion control on the output voltage of the target battery cluster. Combined with the control and management logic of the second control chip on the detection board, it is equivalent to allowing the second control chip to take over the logic management function of the PCS in the energy storage system.

[0015] This configuration allows multiple battery clusters in the energy storage system to be connected in parallel on the AC side, with the resulting output voltage fed into the grid. Since the battery clusters are completely isolated on the DC side, this not only eliminates coupling interference and fault transmission between clusters but also further enhances the safety and reliability of the energy storage system during operation. Furthermore, because the detection board manages each battery cluster individually, adding additional clusters to the system only requires connecting the new battery management module to the detection board; no new PCS or reconfiguration of the DC bus is needed. This architecture further improves flexibility when expanding battery cluster capacity. Simultaneously, since the detection board controls each battery management module individually, even if a faulty battery cluster exists among multiple clusters, it can be isolated, significantly improving the availability of the energy storage system.

[0016] Correspondingly, the control method for an energy storage system provided by the present invention also has the above-mentioned beneficial effects. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a structural diagram of a combiner device for an energy storage system provided in an embodiment of the present invention; Figure 2 This is a structural diagram of a combiner device for another energy storage system provided in an embodiment of the present invention; Figure 3 A flowchart of a control method for an energy storage system provided in an embodiment of the present invention; Figure 4 A flowchart illustrating the grid connection operation of an energy storage system provided in an embodiment of the present invention; Figure 5 This is a flowchart illustrating an energy storage system performing an off-grid operation, as provided in an embodiment of the present invention. Figure 6 This is an operation flowchart of an energy storage system when an early warning is triggered, provided as an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 , Figure 1 This is a structural diagram of a combiner device for an energy storage system provided in an embodiment of the present invention. The device includes: N battery management modules 11 are connected one-to-one with N battery clusters 10; the target battery management module is any one of the N battery management modules 11; the target battery management module includes: a target DC control unit for electrical protection of the target battery cluster and a target power conversion unit for AC conversion and current control of the output voltage of the target battery cluster; N≥2; The detection board 12, equipped with a first control chip and a second control chip, is connected to N battery management modules 11. It is used to collect the operating parameters of the target battery clusters and to regulate the target DC control unit and the target power conversion unit through the first control chip and the second control chip, respectively, so as to control the N battery clusters to be connected to or disconnected from the grid. The AC combiner module 13 is connected to N battery management modules 11 and the detection board 12, and is used to combine the voltage output by the N battery management modules 11 into the power grid.

[0021] In this embodiment, a current-combining device for an energy storage system is provided. This device can solve the technical problems existing in the prior art when combining multiple battery clusters 10 in an energy storage system, such as poor safety, strong coupling interference between battery clusters, low availability of the energy storage system, and poor expansion flexibility.

[0022] The current combiner device provided in this embodiment includes N battery management modules 11, a detection board 12, and an AC current combiner module 13. The N battery management modules 11 are connected one-to-one with the N battery clusters 10, the N battery management modules 11 are connected to the detection board 12, and the N battery management modules 11 and the detection board 12 are also connected to the AC current combiner module 13.

[0023] To make the technical solution described in this application more universal, in this embodiment, any one of the N battery management modules 11 is named the target battery management module. The target battery management module includes a target DC control unit and a target power conversion unit. Specifically, the target DC control unit is used for electrical protection of the target battery cluster. The target power conversion unit is used for AC conversion and current control of the output voltage of the target battery cluster. Functionally, the target DC control unit corresponds to the high-voltage box in the energy storage system, and the target power conversion unit corresponds to the PCS in the energy storage system.

[0024] It should be noted that in practical applications, the N battery management modules described in this embodiment are housed in the same enclosure or cabinet. Furthermore, the current collector provided in this embodiment is connected to the rear end of the N battery clusters. Once this current collector is connected to the rear end of the N battery clusters, there is no need to install a PCS in the energy storage system.

[0025] To adapt to the target DC control unit and target power conversion unit in the target battery management module 11, in this embodiment, a first control chip and a second control chip are set in the detection board 12. The first control chip internally runs the algorithm logic of the BCU (Battery Control Unit), that is, it needs to calculate the SOC (State of Charge), SOH (State of Health), overvoltage, and undervoltage of the target battery cluster 10. In this configuration, the first control chip is essentially an embedded BCU in the energy storage system. It can directly collect the total voltage, cluster current, and insulation resistance of the target battery cluster, without requiring an external BCU in the energy storage system. The second control chip controls the target power conversion unit, converting the high-voltage DC output from the target battery cluster into AC.

[0026] In practical applications, the first control chip can be set as an MCU (Micro Controller Unit) with an ARM architecture, and the second control chip can be set as a DSP (Digital Signal Processor).

[0027] The AC power output from the N battery management modules 11 can be fed into the power grid via the AC combiner module 13. In this embodiment, the AC power output from the N battery management modules 11 is controlled by the same detection board 12. The detection board 12 can synchronously control the amplitude, phase, and frequency of the AC power output from the N battery management modules 11, and ultimately realize the grid connection and disconnection operation of the N battery clusters 10.

[0028] Since the parallel battery cluster architecture provided in this embodiment exhibits current source characteristics, the output voltage of each battery cluster can be allocated on demand through this architecture. That is, when the detection board 12 identifies that different battery clusters have different states of charge, it can implement an asymmetric power control mode for different battery clusters. For example, it can control the charging power of the first battery cluster 10 to be 10kW, while controlling the charging power of the second battery cluster 10 to be 20kW.

[0029] Furthermore, in this embodiment, since each battery cluster has an independent inverter system, the detection board 12 can execute different charging and discharging control logic for different battery clusters. For example, when the SOC of a battery cluster is low, it can be charged more and discharged less; while when the SOC of a battery cluster is high, it can be discharged more and charged less. In this way, the throughput of the energy storage system can be maximized in the scenario of mixing new and old battery clusters.

[0030] It should be noted that in the technical solution provided in this embodiment, since the DC side of the N battery clusters 10 is inverter isolated through AC conversion, even if a battery cluster with a short circuit fault occurs in the N battery clusters 10, it will not affect the normal operation of the other battery clusters. Compared with the parallel DC side scheme of the energy storage system in the prior art, this can significantly improve the safety and reliability of the energy storage system during operation.

[0031] Clearly, in this embodiment, since the target DC control unit can provide electrical protection for the target battery cluster, combined with the control and management logic of the first control chip in the detection board, it is equivalent to allowing the first control chip to take over the logic management function of the BCU in the energy storage system. Similarly, the target power conversion unit can perform AC conversion and current control on the output voltage of the target battery cluster. Combined with the control and management logic of the second control chip in the detection board, it is equivalent to allowing the second control chip to take over the logic management function of the PCS in the energy storage system. With this configuration, multiple battery clusters in the energy storage system can be connected in parallel on the AC side, and the parallel output voltage can be fed into the power grid. Because the battery clusters are completely isolated on the DC side, this not only eliminates coupling interference and fault transmission between battery clusters, but also further improves the safety and reliability of the energy storage system during operation. Furthermore, because the detection board manages each battery cluster individually, when additional battery clusters need to be added to the energy storage system, only a new battery management module needs to be connected to the detection board. No new PCS (Power Control System) is required, nor is reconfiguration of the DC bus necessary. Therefore, this architecture further enhances the flexibility when expanding battery cluster capacity. Simultaneously, since the detection board controls each battery management module individually, even if a faulty battery cluster exists among multiple clusters, the faulty cluster can be isolated, thereby significantly improving the availability of the energy storage system.

[0032] Please see Figure 2 , Figure 2 This is a structural diagram of a combiner device for another energy storage system provided in an embodiment of the present invention. To enable those skilled in the art to better understand the implementation principle of the present invention, in... Figure 2 The shown combiner device contains only two battery clusters, and the first battery management module in the combiner device is used as the target battery management module to specifically explain its internal structure. Figure 2 In this module, the target battery management module includes a target DC control unit 101 and a target power conversion unit 102.

[0033] The target DC control unit 101 includes: a first filter module F11 for filtering the output voltage of the target battery cluster, a circuit breaker QF1, a DC fuse FU10, a precharge resistor R11, a precharge relay KM13, a positive relay KM11, and a negative relay KM12. Specifically, the two output terminals of the first filter module F11 are connected to the first and second terminals of the circuit breaker QF1, respectively; the third terminal of the circuit breaker QF1 is connected to the first terminal of the negative relay KM12; the second terminal of the negative relay KM12 is connected to the first input terminal of the target power conversion unit 102; the fourth terminal of the circuit breaker QF1 is connected to the first terminal of the DC fuse FU10; the second terminal of the DC fuse FU10 is connected to the first terminal of the pre-charge resistor R11 and the first terminal of the positive relay KM11, respectively; the second terminal of the positive relay KM11 is connected to the second input terminal of the target power conversion unit 102; the second terminal of the pre-charge resistor R11 is connected to the first terminal of the pre-charge relay KM13; and the second terminal of the pre-charge relay KM13 is connected to the second input terminal of the target power conversion unit 102. The sampling control terminal A1 of the first control chip A is connected to the control terminal of circuit breaker QF1, the control terminal of positive relay KM11, the control terminal of negative relay KM12, and the control terminal of precharge relay KM13. The sampling control terminal of the first control chip A is also connected to the current detector HALL set at the third terminal of circuit breaker QF1.

[0034] In this embodiment, the structure of the target DC control unit 101 is specifically described. With this configuration of the target DC control unit 101, the first control chip A can directly acquire the total voltage, cluster current, and insulation resistance of the target battery cluster, and control the target DC control unit 101 by running the internally configured BCU algorithm logic.

[0035] In this embodiment, the positive relay KM11 and negative relay KM12 in the target DC control unit 101 can be directly controlled by the first control chip A. When the first control chip A detects that the voltage difference of the target battery cluster is too large and maintenance is required, the first control chip A only needs to disconnect the positive relay KM11 and negative relay KM12. Other battery clusters can still perform normal charging and discharging logic through the combiner device provided in this embodiment, truly realizing "one machine for two purposes, without interference".

[0036] Clearly, the technical solution provided in this embodiment can not only improve the availability of the energy storage system, but also enhance the convenience of maintaining the battery clusters.

[0037] Please continue reading Figure 2 The target power conversion unit 102 includes: a power board M11, a second filter module 001, a first contactor J11, a second contactor J12, a third contactor J13, a first fuse FU11, a second fuse FU12, and a third fuse FU13. The first and second input terminals of the power board M11 are connected to the second terminals of the negative relay KM12 and the positive relay KM11, respectively. The first, second, and third output terminals of the power board M11 are connected to the first, second, and third input terminals of the second filter module 001, respectively. The first, second, and third output terminals of the second filter module 001 are connected to the first terminals of the first contactor J11, the second contactor J12, and the third contactor J13, respectively. The second terminals of the first contactor J11, the second contactor J12, and the third contactor J13 are connected to the first terminals of the first fuse FU11, the second fuse FU12, and the third fuse FU13, respectively. The second terminals of the first fuse FU11, the second fuse FU12, and the third fuse FU13 are connected to the AC busbar module 13, respectively. The first terminal of the second control chip B is connected to the control terminal of the power board M11. The second terminal of the second control chip B is connected to the first output terminal, the second output terminal, and the third output terminal of the power board M11. The third terminal of the second control chip B is connected to the control terminal of the second filter module 001. The fourth terminal of the second control chip B is connected to the first output terminal, the second output terminal, and the third output terminal of the second filter module 001. The fifth terminal of the second control chip B is connected to the first terminal of the first fuse FU11, the first terminal of the second fuse FU12, and the first terminal of the third fuse FU13. The control terminal of the second control chip B is connected to the control terminals of the first contactor J11, the second contactor J12, and the third contactor J13. Correspondingly, the first input terminal and the second input terminal of the power board M11 are the first input terminal and the second input terminal of the target power conversion unit 102, respectively.

[0038] In this embodiment, the structure of the target power conversion unit 102 is specifically described. The second filtering module 001 in the target power conversion unit 102 is composed of an AC filter F2, a first inductor L11, a second inductor L12, and a third inductor L13.

[0039] The DC power (e.g., 750V~1300V) output from the target battery cluster is converted into AC power (e.g., 690V / 50Hz) by the power board M11. Then, the AC power output from the power board M11 is filtered by the second filter module 001, and after harmonics are filtered out by AC inductors L11, L12, and L13, the AC power output from the power board M11 is sent to the AC combiner module 13. It should be noted that the AC combiner module 13 consists of a surge protector (SPD) and an AC circuit breaker (QF0).

[0040] Obviously, the technical solution provided in this embodiment can reliably convert the DC power output by the target battery cluster into AC power.

[0041] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the combiner device of the above energy storage system further includes: An isolation transformer is connected between the target DC control unit and the target power conversion unit to provide electrical isolation between the target battery cluster and the target power conversion unit.

[0042] In this embodiment, an isolation transformer can also be installed between the target DC control unit and the target power conversion unit to provide electrical isolation between the target battery cluster and the target power conversion unit. This further enhances the safety of the energy storage system during use.

[0043] In practical applications, the isolation transformer can be configured as either an isolation inverter or a DAB (Dual Active Bridge).

[0044] Clearly, the technical solution provided in this embodiment can further improve the safety of energy storage systems.

[0045] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the combiner device of the above energy storage system further includes: A DC / AC converter is connected between the target DC control unit and the target power conversion unit to convert the output voltage of the target battery cluster.

[0046] In this embodiment, a DC / AC converter can also be set between the target DC control unit and the target power conversion unit, and the DC / AC converter can be used to convert the output voltage of the target battery cluster. This allows the combiner device provided in this embodiment to provide a wider voltage output range and enables the energy storage system to be compatible with battery clusters of different voltage levels, thus further improving the compatibility and flexibility of the energy storage system.

[0047] Obviously, the technical solution provided in this embodiment can significantly improve the flexibility of the combiner device provided in this application in practical applications.

[0048] From the above, we can see that, Figure 2 The parallel architecture of the battery clusters on the AC side shown has the following significant advantages compared to the discrete parallel architecture on the AC side of existing energy storage systems, which involves two high-voltage boxes and two string PCS: First: Reduce the size of energy storage systems and lower their construction costs. Through... Figure 2 The architecture shown can combine the two high-voltage boxes, two PCS cabinets, copper busbars, fans and communication cables in the existing technology into a whole, which can reduce the footprint of the energy storage system by 40% and reduce the cost of the energy storage system by 20% to 25%.

[0049] Second, it reduces circulating current losses and improves system availability. Because the parallel architecture of the battery clusters on the AC side physically isolates the circulating current path on the DC side, circulating current losses can be reduced to almost zero. Furthermore, if one battery management module fails, other battery management modules can instantly take over the charging and discharging functions corresponding to that channel, thus improving the availability of the energy storage system.

[0050] Third: Enhanced compatibility. The parallel architecture of battery clusters on the AC side can connect battery clusters from different manufacturers, with different capacities and different levels of degradation. Each battery cluster can be independently regulated by an inverter, allowing different battery clusters to operate stably within the same energy storage system. This significantly reduces the limitations that exist when expanding or replacing battery clusters in the later stages.

[0051] Fourth: Simplify the wiring complexity of energy storage systems. At the installation site, simply insert the positive and negative cables of the two battery clusters into the DC interface of the combiner unit, and connect the output cable of the combiner unit to the power grid. This reduces wiring work by 60% and shortens the commissioning period by 50%.

[0052] Of course, the above only illustrates the advantages of a combiner device by using two battery clusters as an example. The more battery clusters in the energy storage system, the more obvious the advantages of the parallel architecture of the battery clusters on the AC side will be, which will not be elaborated upon here.

[0053] Please see Figure 3 , Figure 3 This is a flowchart of a control method for an energy storage system provided in an embodiment of the present invention. The method is applied to a detection board in a combiner device of the aforementioned energy storage system, and includes: Step S11: When N battery clusters in the energy storage system need to perform grid connection operation, the operating parameters of the target battery cluster are detected by the first control chip; the combiner device is installed in the energy storage system; Step S12: When it is determined from the operating parameters of the target battery cluster that the connection lines of the target DC control unit are all normal and the target battery cluster meets the high voltage judgment conditions, a pre-charge command is sent to the target battery cluster according to the grid connection command. When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is adjusted by the second control chip so that N battery clusters can perform grid connection operation. Step S13: When N battery clusters need to perform off-grid operation, the target battery cluster is controlled to stop performing charging and discharging operation, and the target power conversion unit is controlled to perform power reduction operation through the second control chip. When the output power of the target power conversion unit is less than the first preset threshold, the line connection with the target battery cluster is disconnected, and the off-grid operation of N battery clusters is completed simultaneously.

[0054] This embodiment specifically describes a control method for an energy storage system. This method can control N battery clusters in the energy storage system to perform grid-connected operations and also control them to perform off-grid operations. It should be noted that in this application, the logic for each battery cluster performing grid-connected and off-grid operations remains consistent.

[0055] This section uses a target battery cluster as an example to explain in detail the grid connection and disconnection process of the battery cluster. When the target battery cluster needs to perform grid connection operation, the first control chip and the second control chip in the detection board can interact with each other. At this time, through the control of the target DC control unit by the first control chip and the regulation of the target power conversion unit by the second control chip, the target battery cluster can be connected to the grid, and all battery clusters can be connected to the grid simultaneously.

[0056] When connecting a target battery cluster to the grid, the first step is to determine whether the connection lines of the target DC control unit are functioning correctly based on the operating parameters of the target battery cluster. If there is a problem with the connection lines of the target DC control unit, the target battery cluster must be prevented from accessing high voltage to avoid safety accidents. If the connection lines of the target DC control unit are normal, and the target battery cluster meets the conditions for accessing high voltage, a pre-charge command can be issued to the target battery cluster to begin charging according to the grid connection command. When the target battery cluster is charged to a certain value of its rated capacity, it indicates that the target battery cluster has been pre-charged. At this point, the output voltage of the target power conversion unit can be adjusted through the second control chip, thereby enabling the target battery cluster to be connected to the grid.

[0057] When a target battery cluster needs to perform an off-grid operation, the detection board first needs to control the target battery cluster to operate at reduced power and stop charging and discharging operations. When the output power of the target power conversion unit is less than a first preset threshold, the line connection with the target battery cluster can be disconnected, allowing the target battery cluster to perform the off-grid operation. At the same time, other battery clusters will also perform off-grid operations synchronously in the same way.

[0058] Clearly, the technical solution provided in this embodiment can ensure the safety and reliability of the battery cluster when performing off-grid operations.

[0059] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. Please refer to [link / reference]. Figure 4 , Figure 4 This is a flowchart illustrating the grid connection operation of an energy storage system according to an embodiment of the present invention. In a preferred embodiment, the above steps include: when the connection lines of the target DC control unit are determined to be normal based on the operating parameters of the target battery cluster, and the target battery cluster meets the conditions for high voltage connection, a pre-charge command is issued to the target battery cluster according to the grid connection command; and when the target battery cluster is pre-charged, the output voltage of the target power conversion unit is adjusted by the second control chip to enable N battery clusters to perform grid connection operation, including: Step S201: When the target DC control unit includes: a first filter module for filtering the output voltage of the target battery cluster, a circuit breaker, a DC fuse, a pre-charge resistor, a pre-charge relay, a positive relay, and a negative relay; wherein, the two output terminals of the first filter module are connected to the first and second terminals of the circuit breaker, respectively; the third terminal of the circuit breaker is connected to the first terminal of the negative relay; the second terminal of the negative relay is connected to the first input terminal of the target power conversion unit; the fourth terminal of the circuit breaker is connected to the first terminal of the DC fuse; the second terminal of the DC fuse is connected to the first terminal of the pre-charge resistor and the first terminal of the positive relay, respectively; the second terminal of the positive relay is connected to the first input terminal of the target power conversion unit; the second terminal of the pre-charge resistor is connected to the first terminal of the pre-charge relay; and the second terminal of the pre-charge relay is connected to the second input terminal of the target power conversion unit. Step S202: Determine whether the circuit breaker is in the open state; Step S203: If yes, then determine whether both the negative and positive relays are normal based on the operating parameters of the target battery cluster; Step S204: If yes, then check whether the insulation resistance between the positive terminal of the target battery cluster and ground and the insulation resistance between the negative terminal of the target battery cluster and ground are both normal. Step S205: If yes, then the target battery cluster is determined to meet the conditions for applying high voltage. Step S206: When a grid connection command is received from the BAU or EMS in the energy storage system, determine whether the combiner cabinet in the energy storage system is in the closed state; the combiner device is installed in the energy storage system. Step S207: If yes, then send a pre-charge command to the target battery cluster; Step S208: When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is regulated by the second control chip; Step S209: When the output voltage of the target power conversion unit is synchronized with the voltage of the power grid, the target power conversion unit is controlled to be connected to the power grid, and the grid connection operation of N battery clusters is completed synchronously. As a preferred embodiment, after determining whether the circuit breaker is in the open state in step S202 above, the method further includes: Step S210: If not, disconnect the shunt trip unit in the circuit breaker; Accordingly, after determining whether the negative and positive relays are both normal based on the operating parameters of the target battery cluster, step S204 further includes: if not, then continue to execute step S210: disconnect the shunt trip unit in the circuit breaker.

[0060] This embodiment specifically describes the grid connection process for N battery clusters. The grid connection process described in this embodiment is based on... Figure 2 The circuit structure of the target DC control unit shown is used as an example for explanation. Furthermore, in this embodiment, the grid connection logic of all battery clusters is explained using the target battery cluster as an example.

[0061] When performing grid connection operation on the target battery cluster, the first step is to determine whether the circuit breaker in the target DC control unit is in the open state. If the circuit breaker is determined to be in the closed state, the shunt trip unit in the circuit breaker needs to be disconnected, and high voltage should be prohibited from being applied to the downstream circuit. If the circuit breaker is in the open state, then it is necessary to determine whether both the negative and positive relays are functioning properly based on the operating parameters of the target battery cluster.

[0062] Specifically, when determining whether a negative relay is functioning correctly, it refers to testing... Figure 2 Check if the voltage difference between 1BAT- and CH2 is less than a preset value. If the voltage difference is less than or equal to the preset value, the negative relay is normal. If the voltage difference is greater than the preset value, the negative relay is stuck. Similarly, when judging whether the positive relay is normal, it refers to checking... Figure 2Check if the voltage difference between 1BAT+ and CH1 is less than a preset value. If the voltage difference is less than or equal to the preset value, the positive relay is normal. If the voltage difference is greater than the preset value, the positive relay is stuck. When the positive relay and / or negative relay are stuck, the shunt trip unit in the circuit breaker needs to be disconnected.

[0063] When both the positive and negative relays are normal, it is still necessary to continue to check whether the insulation resistance between the positive terminal and ground of the target battery cluster and the insulation resistance between the negative terminal and ground of the target battery cluster are both normal.

[0064] Specifically, when checking whether the insulation resistance between the positive terminal and ground of the target battery cluster is normal, it refers to checking... Figure 2 Is the insulation resistance between point 1BAT+ and ground greater than or equal to the preset resistance value? If so... Figure 2 If the insulation resistance between point 1BAT+ and ground is greater than or equal to the preset resistance value, it indicates that there is no grounding fault at the positive terminal of the target battery cluster. Figure 2 If the insulation resistance between the 1BAT+ terminal and ground is less than the preset value, it indicates a grounding fault at the positive terminal of the target battery cluster. Similarly, when checking whether the insulation resistance between the negative terminal and ground of the target battery cluster is normal, it refers to checking... Figure 2 Is the insulation resistance between 1BAT and ground greater than or equal to the preset resistance value? If so... Figure 2 If the insulation resistance between the 1BAT point and ground is greater than or equal to the preset resistance value, it indicates that there is no grounding fault at the negative terminal of the target battery cluster. Figure 2 If the insulation resistance between point 1BAT- and ground is less than the preset resistance, it indicates that a ground fault has occurred at the negative terminal of the target battery cluster. If a ground fault occurs at either the negative or positive terminal of the target battery cluster, high voltage should be prohibited from being applied to subsequent circuits.

[0065] When both the positive and negative insulation resistance values ​​of the target battery cluster to ground are normal, it indicates that the target battery cluster meets the conditions for high-voltage connection, and the subsequent grid connection process can continue. During this process, if the target battery cluster can be powered locally, the detection board can wait for the grid connection command issued by the BAU (Battery Array Unit). If the target battery cluster needs to be powered remotely, the detection board can wait for the grid connection command issued by the EMS. When the detection board receives the grid connection command, if the energy storage system is in local mode or a combination of remote and local modes, the detection board needs to determine whether the combiner cabinet in the energy storage system is in the closed state.

[0066] If the combiner cabinet is in the closed state, the detection board can send a pre-charge command to the target battery cluster. If the combiner cabinet is in the closed state, it needs to be closed. When the combiner cabinet is in the closed state, the detection board can send a pre-charge command to the target battery cluster, that is, through... Figure 2 The pre-charge resistor R11 and pre-charge relay KM13 are used to charge the target battery cluster. Once the target battery cluster is fully charged, the output voltage of the target power conversion unit can be adjusted via the second control chip. When the output voltage of the target power conversion unit is synchronized with the grid voltage, the detection board can control the target power conversion unit to connect to the grid. Simultaneously, other battery clusters perform the same logical actions, and N battery clusters synchronously complete the grid connection operation. It should be noted that if the target battery cluster fails to pre-charge, a corresponding warning message should be displayed, and the grid connection operation of the N battery clusters should be prohibited.

[0067] Clearly, the technical solution provided in this embodiment can further improve the safety and reliability of battery clusters during grid connection.

[0068] Please see Figure 5 , Figure 5 This is a flowchart illustrating an energy storage system performing off-grid operation according to an embodiment of the present invention. In a preferred embodiment, step S13 involves controlling the target battery cluster to stop charging and discharging operations, and controlling the target power conversion unit to perform a power reduction operation via a second control chip. This is done so that when the output power of the target power conversion unit is less than a first preset threshold, the line connection with the target battery cluster is disconnected, and the off-grid operation of N battery clusters is completed simultaneously. Step S301: Control the target battery cluster to stop performing charging and discharging operations; Step S302: Control the target power conversion unit to perform a power reduction operation through the second control chip, and after a first preset time delay, determine whether the output power of the target power conversion unit is less than the first preset threshold. Step S303: If not, determine that the target power conversion unit has failed and disconnect the shunt trip unit in the circuit breaker; Step S304: If yes, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; Step S305: If not, determine that the positive relay and / or negative relay has a sticking fault, and continue to execute step S303: disconnect the shunt trip unit in the circuit breaker; Step S306: If yes, then determine that the line connection with the target battery cluster has been disconnected, and simultaneously complete the off-grid operation of N battery clusters.

[0069] This embodiment provides a detailed description of the off-grid process for the target battery cluster. When the target battery cluster performs the off-grid operation, it first needs to stop charging and discharging, and then control the target power conversion unit to perform a power reduction operation. If the output power of the target power conversion unit is less than a first preset threshold after a first preset time, the positive and negative relays can be disconnected to perform the off-grid operation. Clearly, this off-grid method avoids current surges to the power grid and the battery cluster.

[0070] If, during the off-grid process, the output power of the target power conversion unit is greater than or equal to a first preset threshold within a first preset time period, it indicates a fault in the target power conversion unit, and the shunt trip unit in the circuit breaker needs to be disconnected. In addition, if the positive relay fails to disconnect during the off-grid process, it indicates a positive relay sticking fault; if the negative relay fails to disconnect, it indicates a negative relay sticking fault. In this embodiment, regardless of whether the positive or negative relay is stuck, the shunt trip unit in the circuit breaker needs to be disconnected.

[0071] Clearly, the technical solution provided in this embodiment can further improve the safety and reliability of battery clusters during off-grid operation.

[0072] Please see Figure 6 , Figure 6 This is a flowchart illustrating the operation of an energy storage system when an early warning is triggered, as provided in an embodiment of the present invention. In a preferred embodiment, the control method further includes: Step S401: Determine whether the energy storage system has triggered the preset alarm conditions; Step S402: If yes, the target power conversion unit is controlled by the second control chip to perform a power reduction operation, and after a second preset time delay, it is determined whether the output power of the target power conversion unit is less than the second preset threshold. Step S403: If not, disconnect the shunt trip unit in the circuit breaker and display the first warning message; Step S404: If yes, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; Step S405: If not, determine that the positive relay and / or negative relay has a sticking fault, disconnect the shunt trip unit in the circuit breaker, and issue a second warning message; Step S406: If yes, then determine that the energy storage system has been shut down and issue a third warning message.

[0073] In this embodiment, to further ensure the safety and reliability of the energy storage system during operation, preset alarm conditions can be set for the energy storage system in advance. If the energy storage system triggers the preset alarm conditions, it indicates that there is a safety hazard in the energy storage system, and at this time, it is necessary to disconnect the power supply to the energy storage system. In this case, the second control chip needs to control the target power conversion unit to perform a power reduction operation, and after a second preset time, it is determined whether the output power of the target power conversion unit is less than a second preset threshold.

[0074] If, after the target power conversion unit performs a power reduction operation, its output power is still greater than or equal to the second preset threshold after a second preset time, it indicates that the energy storage system cannot execute the normal power-down logic. In this case, to prevent further escalation of the fault, the detection board needs to disconnect the shunt trip unit in the circuit breaker and issue the first warning message. If, after the target power conversion unit performs a power reduction operation, its output power is less than the second preset threshold after a second preset time, it indicates that the energy storage system can execute the power-down operation according to normal logic. At this time, the detection board can control the positive and negative relays to disconnect.

[0075] During the disconnection of the positive and negative relays, it is also necessary to check whether each relay is truly disconnected. If either the positive or negative relay is not disconnected, it indicates a sticking fault in either the positive or negative relay. In this case, the shunt trip unit in the circuit breaker needs to be disconnected, and a second warning message should be displayed. If both the positive and negative relays are disconnected, it indicates that the energy storage system has been shut down. At this point, a third warning message should be displayed, and maintenance personnel should be called to repair the energy storage system.

[0076] Obviously, the technical solution provided in this embodiment can handle the alarm faults triggered by the energy storage system and prevent the faults from escalating further, thereby ensuring the overall reliability of the energy storage system during operation.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0078] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0079] The present invention has provided a detailed description of a current-collecting device for an energy storage system and a control method for an energy storage system. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A combiner device for an energy storage system, characterized in that, include: N battery management modules are connected one-to-one with N battery clusters; The target battery management module is any one of the N battery management modules; The target battery management module includes: a target DC control unit for electrical protection of the target battery cluster and a target power conversion unit for AC conversion and current control of the output voltage of the target battery cluster; N≥2; A detection board equipped with a first control chip and a second control chip is connected to all N battery management modules. It is used to collect the operating parameters of the target battery clusters and to regulate the target DC control unit and the target power conversion unit through the first control chip and the second control chip, respectively, so as to control the grid connection and disconnection of the N battery clusters. An AC combiner module is connected to N battery management modules and the detection board, and is used to combine the voltage output by the N battery management modules into the power grid.

2. The energy storage system combiner device according to claim 1, characterized in that, The target DC control unit includes: a first filter module for filtering the output voltage of the target battery cluster, a circuit breaker, a DC fuse, a pre-charge resistor, a pre-charge relay, a positive relay, and a negative relay; In this configuration, the two output terminals of the first filter module are connected to the first and second terminals of the circuit breaker, respectively; the third terminal of the circuit breaker is connected to the first terminal of the negative relay; the second terminal of the negative relay is connected to the first input terminal of the target power conversion unit; the fourth terminal of the circuit breaker is connected to the first terminal of the DC fuse; the second terminal of the DC fuse is connected to the first terminal of the pre-charge resistor and the first terminal of the positive relay, respectively; the second terminal of the positive relay is connected to the second input terminal of the target power conversion unit; the second terminal of the pre-charge resistor is connected to the first terminal of the pre-charge relay; and the second terminal of the pre-charge relay is connected to the second input terminal of the target power conversion unit. The sampling control terminal of the first control chip is connected to the control terminal of the circuit breaker, the control terminal of the positive relay, the control terminal of the negative relay, and the control terminal of the precharge relay. The sampling control terminal of the first control chip is also connected to the current detector set at the third terminal of the circuit breaker.

3. The combiner device for an energy storage system according to claim 2, characterized in that, The target power conversion unit includes: a power board, a second filter module, a first contactor, a second contactor, a third contactor, a first fuse, a second fuse, and a third fuse; The first and second input terminals of the power board are connected to the second terminals of the negative relay and the positive relay, respectively. The first, second, and third output terminals of the power board are connected to the first, second, and third input terminals of the second filter module, respectively. The first, second, and third output terminals of the second filter module are connected to the first, second, and third terminals of the first contactor, the second contactor, and the third contactor, respectively. The second terminals of the first, second, and third contactors are connected to the first, second, and third fuses, respectively. The second terminals of the first, second, and third fuses are connected to the AC combiner module, respectively. The first terminal of the second control chip is connected to the control terminal of the power board. The second terminal of the second control chip is connected to the first output terminal, the second output terminal, and the third output terminal of the power board, respectively. The third terminal of the second control chip is connected to the control terminal of the second filter module. The fourth terminal of the second control chip is connected to the first output terminal, the second output terminal, and the third output terminal of the second filter module. The fifth terminal of the second control chip is connected to the first terminal of the first fuse, the first terminal of the second fuse, and the first terminal of the third fuse. The control terminal of the second control chip is connected to the control terminal of the first contactor, the control terminal of the second contactor, and the control terminal of the third contactor. Accordingly, the first input terminal and the second input terminal of the power board are respectively the first input terminal and the second input terminal of the target power conversion unit.

4. The combiner device for an energy storage system according to claim 1, characterized in that, Also includes: An isolation transformer is connected between the target DC control unit and the target power conversion unit to provide electrical isolation between the target battery cluster and the target power conversion unit.

5. The combiner device for an energy storage system according to claim 1, characterized in that, Also includes: A DC / AC converter is connected between the target DC control unit and the target power conversion unit to convert the output voltage of the target battery cluster.

6. A control method for an energy storage system, characterized in that, A detection board applied in a combiner device of an energy storage system according to any one of claims 1 to 5, comprising: When N battery clusters in the energy storage system need to perform grid connection operations, the operating parameters of the target battery clusters are detected by the first control chip; the combiner device is installed in the energy storage system. When it is determined from the operating parameters of the target battery cluster that the connection lines of the target DC control unit are all normal and the target battery cluster meets the high voltage determination conditions, a pre-charge command is issued to the target battery cluster according to the grid connection command. When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is adjusted by the second control chip so that N battery clusters can perform grid connection operation. When N battery clusters need to perform off-grid operation, the target battery cluster is controlled to stop performing charging and discharging operations, and the target power conversion unit is controlled by the second control chip to perform power reduction operation. When the output power of the target power conversion unit is less than a first preset threshold, the line connection with the target battery cluster is disconnected, and the off-grid operation of N battery clusters is completed simultaneously.

7. The control method for an energy storage system according to claim 6, characterized in that, When the connection lines of the target DC control unit are determined to be normal based on the operating parameters of the target battery cluster, and the target battery cluster meets the high-voltage condition, a pre-charge command is issued to the target battery cluster according to the grid connection command. After the target battery cluster has completed pre-charging, the output voltage of the target power conversion unit is adjusted by the second control chip to enable the N battery clusters to perform grid connection operations, including: When the target DC control unit includes: a first filter module for filtering the output voltage of the target battery cluster, a circuit breaker, a DC fuse, a pre-charge resistor, a pre-charge relay, a positive relay, and a negative relay; wherein, the two output terminals of the first filter module are respectively connected to the first and second terminals of the circuit breaker, the third terminal of the circuit breaker is connected to the first terminal of the negative relay, the second terminal of the negative relay is connected to the first input terminal of the target power conversion unit, the fourth terminal of the circuit breaker is connected to the first terminal of the DC fuse, the second terminal of the DC fuse is connected to the first terminal of the pre-charge resistor and the first terminal of the positive relay, the second terminal of the positive relay is connected to the second input terminal of the target power conversion unit, the second terminal of the pre-charge resistor is connected to the first terminal of the pre-charge relay, and the second terminal of the pre-charge relay is connected to the second input terminal of the target power conversion unit; Determine whether the circuit breaker is in the open state; If so, determine whether both the negative relay and the positive relay are functioning normally based on the operating parameters of the target battery cluster; If so, check whether the insulation resistance between the positive terminal of the target battery cluster and ground and the insulation resistance between the negative terminal of the target battery cluster and ground are both normal. If so, the target battery cluster is determined to meet the conditions for applying high voltage. When a grid connection command is received from the BAU or EMS in the energy storage system, it is determined whether the combiner cabinet in the energy storage system is in the closed state. If so, a pre-charge command is sent to the target battery cluster; When the target battery cluster is pre-charged, the output voltage of the target power conversion unit is regulated by the second control chip; When the output voltage of the target power conversion unit is synchronized with the voltage of the power grid, the target power conversion unit is controlled to be connected to the power grid, and the grid connection operation of N battery clusters is completed synchronously.

8. The control method for an energy storage system according to claim 7, characterized in that, After determining whether the circuit breaker is in an open state, the method further includes: If not, disconnect the shunt trip unit in the circuit breaker; Accordingly, after determining whether both the negative relay and the positive relay are functioning normally based on the operating parameters of the target battery cluster, the process further includes: If not, continue with the step of disconnecting the shunt trip unit in the circuit breaker.

9. The control method for an energy storage system according to claim 7, characterized in that, The control mechanism stops the target battery cluster from performing charging and discharging operations, and controls the target power conversion unit to perform a power reduction operation via the second control chip. This is done so that when the output power of the target power conversion unit is less than a first preset threshold, the line connection with the target battery cluster is disconnected, and the off-grid operation of N battery clusters is completed simultaneously. Control the target battery cluster to stop performing charging and discharging operations; The second control chip controls the target power conversion unit to perform a power reduction operation, and after a first preset time delay, it is determined whether the output power of the target power conversion unit is less than the first preset threshold. If not, the target power conversion unit is determined to be faulty, and the shunt trip unit in the circuit breaker is disconnected; If so, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; If not, it is determined that the positive relay and / or the negative relay has a sticking fault, and the step of disconnecting the shunt trip unit in the circuit breaker is continued; If so, it is determined that the line connection with the target battery cluster has been disconnected, and the off-grid operation of N battery clusters is completed simultaneously.

10. The control method for an energy storage system according to claim 7, characterized in that, Also includes: Determine whether the energy storage system has triggered a preset alarm condition; If so, the target power conversion unit is controlled by the second control chip to perform a power reduction operation, and after a second preset time delay, it is determined whether the output power of the target power conversion unit is less than a second preset threshold. If not, disconnect the shunt trip unit in the circuit breaker and display the first warning message; If so, then control the positive relay and the negative relay to disconnect, and determine whether both the positive relay and the negative relay are disconnected; If not, it is determined that the positive relay and / or the negative relay has a sticking fault, and the shunt trip unit in the circuit breaker is disconnected, and a second warning message is issued; If so, the energy storage system is determined to have shut down, and a third warning message is issued.

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