Battery stack energy storage system and control method

Abstract

The invention provides a cell stack energy storage system and a control method, which are applied to the technical field of energy storage control and are used for solving the problem that the capacity and available power of the cell stack energy storage system are reduced due to a short-plate effect between cell clusters. Specifically, the anode output end of each battery cluster is connected to a positive DC bus through a power distribution unit; each power distribution unit comprises an energy storage control unit and a charging and discharging control unit which are connected in parallel; and when the battery cluster meets the trigger condition of the full-charge and full-discharge protection mechanism, after the energy storage control unit corresponding to the battery cluster is switched from the off state to the on state, the charge and discharge control unit corresponding to the battery cluster is switched from the on state to the off state, so that the energy storage control unit keeps the battery cluster in an online coupling state in an energy storage mode. The available power of the cell stack energy storage system is improved, all the cell clusters in the cell stack can be fully charged and discharged, and the capacity of the cell stack energy storage system is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage control, and more specifically, to a battery stack energy storage system and a control method. Background Art

[0002] With the continuous development of energy storage technology, large-capacity high-voltage energy storage systems are increasingly used in power systems. Such systems are mainly used in scenarios such as grid peak regulation, renewable energy access, and emergency power supply. Existing large-capacity high-voltage energy storage systems mainly adopt two architectures: one is that multiple groups of battery clusters are directly connected in parallel and then connected to the tower PCS (Power Conversion System) architecture; the other is that a single cluster of batteries is connected to the PCS after converging through a DC / DC module or directly uses a string-type PCS to form an energy storage system.

[0003] For large-capacity high-voltage energy storage systems that directly connect multiple battery clusters in parallel to a tower PCS architecture, in actual operation, the so-called "short board effect" is caused by inherent manufacturing differences, inconsistent charge and discharge characteristics, and different aging rates between the battery clusters. Specifically, when multiple battery clusters work in parallel, the battery cluster with the worst performance will determine the available capacity and charge and discharge efficiency of the entire battery stack. Over time, this difference will be further exacerbated, causing the overall performance of the system to gradually decline, the available capacity to decrease, and the operating efficiency to decrease. In addition, when multiple battery clusters are directly connected in parallel, if full charge or full discharge operations are to be achieved, measures must be taken for the battery cluster that reaches the limit state first, such as tripping the contactor to disconnect it from the system. However, frequent load operations under full charge and discharge conditions for a long time will cause the life of the electrical switch to be drastically shortened, and once a battery cluster is decoupled, the available power provided to the outside by the entire battery stack will also be reduced accordingly.

[0004] Although the above problems can be alleviated by adding DC / DC modules to each battery cluster or using string PCS, both solutions have disadvantages such as high cost, complex electrical structure, high control system complexity, high failure rate and high operation and maintenance costs. Therefore, under the existing technical conditions, how to effectively overcome a series of problems caused by the short board effect between battery clusters has become one of the key challenges to improve the performance of large-capacity high-voltage energy storage systems. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a battery stack energy storage system and a control method to solve the problem of reduced capacity and available power of the battery stack energy storage system caused by the short board effect between battery clusters in the prior art.

[0006] In a first aspect, the present invention provides a battery stack energy storage system, comprising: a battery stack consisting of at least two battery clusters, a power distribution unit corresponding to each battery cluster, and a battery management system;

[0007] The negative output terminal of each battery cluster is connected to the negative DC bus, and the positive output terminal of each battery cluster is connected to the positive DC bus via a power distribution unit; each power distribution unit includes an energy storage control unit and a charge and discharge control unit connected in parallel;

[0008] The battery management system is respectively connected to each battery cluster and the energy storage control unit and the charge and discharge control unit in the power distribution unit corresponding to each battery cluster;

[0009] For each battery cluster, when the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism, after the energy storage control unit corresponding to the battery cluster is switched from the disconnected state to the connected state, the charge and discharge control unit corresponding to the battery cluster is switched from the connected state to the disconnected state, so that the energy storage control unit keeps the battery cluster in an online coupling state through energy storage.

[0010] In an optional implementation, the energy storage control unit includes: a resistor, an energy storage capacitor, and a first controllable switch connected in series; a control end of the first controllable switch is connected to a battery management system.

[0011] In an optional implementation, the charge and discharge control unit includes: a second controllable switch; a control end of the second controllable switch is connected to the battery management system.

[0012] In an optional embodiment, the battery stack energy storage system further includes: a bus capacitor; the bus capacitor is connected between the positive DC bus and the negative DC bus, and the capacitance of the bus capacitor is smaller than the capacitance of the energy storage capacitor.

[0013] In a second aspect, the present invention provides a battery stack control method, which is applied to a battery management system in a battery stack energy storage system as in any one of the aforementioned embodiments, comprising:

[0014] Acquire first power state data of each battery cluster in the battery stack energy storage system;

[0015] Based on the first power status data of each battery cluster, detecting whether each battery cluster meets the triggering condition of the full charge and discharge protection mechanism;

[0016] When it is detected that any battery cluster meets the triggering condition of the full charge and discharge protection mechanism, the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be connected, and then the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be disconnected.

[0017] In an optional implementation, the first power state data includes current charge state data and current working state data; based on the first power state data of each battery cluster, detecting whether each battery cluster meets the triggering condition of the full charge and discharge protection mechanism includes:

[0018] For each battery cluster, if it is detected based on the current working status data of the battery cluster that the battery cluster is in charging mode, and based on the current charge state data of the battery cluster that the battery cluster is in full charging state, then it is determined that the battery cluster meets the triggering conditions of the full charging and discharging protection mechanism; if it is detected based on the current working status data of the battery cluster that the battery cluster is in discharging mode, and based on the current charge state data of the battery cluster that the battery cluster is in full discharging state, then it is determined that the battery cluster meets the triggering conditions of the full charging and discharging protection mechanism.

[0019] In an optional implementation, before obtaining the first power state data of each battery cluster in the battery stack energy storage system, the method further includes:

[0020] Acquiring second power status data of each battery cluster;

[0021] Based on the second power status data of each battery cluster, detecting whether each battery cluster meets a safe power-on condition;

[0022] When it is detected that any battery cluster does not meet the safe power-on conditions, the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be connected, until it is detected that the battery cluster meets the safe power-on conditions, the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be connected, and the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be disconnected.

[0023] In an optional embodiment, the second power state data includes a difference between an output voltage of the battery cluster and a bus voltage; based on the second power state data of each battery cluster, detecting whether each battery cluster meets a safe power-on condition includes:

[0024] For each battery cluster, if it is detected that the difference between the output voltage of the battery cluster and the bus voltage is less than the voltage difference threshold, it is determined that the battery cluster meets the safe power-on conditions; if it is detected that the difference between the output voltage of the battery cluster and the bus voltage is greater than or equal to the voltage difference threshold, it is determined that the battery cluster does not meet the safe power-on conditions.

[0025] In an optional implementation, if the battery cluster that does not meet the safety power-on condition is the first battery cluster in the battery stack energy storage system, before controlling the circuit connection of the charge and discharge control unit corresponding to the battery cluster, the method further includes:

[0026] A capacitor voltage of a bus capacitor connected between a positive DC bus and a negative DC bus is obtained, and it is determined that the capacitor voltage of the bus capacitor reaches a steady-state voltage.

[0027] In an optional implementation manner, the process of detecting whether each battery cluster meets the safety power-on condition based on the second power state data of each battery cluster further includes:

[0028] When it is detected that any battery cluster meets the safe power-on condition, the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be connected, and the circuit connection of the energy storage control unit corresponding to the battery cluster is kept disconnected.

[0029] The beneficial effects of this application are as follows:

[0030] In the present application, by setting a parallel-connected energy storage control unit and a charge and discharge control unit between the positive output terminal of each battery cluster and the positive DC bus, and when the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism, the battery cluster is controlled to be connected to the positive DC bus through the energy storage control unit. The energy storage control unit itself has the function of isolating DC power and connecting AC power, which can not only effectively prevent overcharging and over-discharging of the battery cluster, but also provide protection for the safety of the battery cluster. Moreover, the online coupling of the battery cluster can be realized to improve the available power of the battery stack energy storage system. In addition, after each battery cluster in the battery stack is fully charged or completely discharged, it is connected to the positive DC bus through the energy storage control unit, and all the battery clusters in the battery stack can be fully charged and discharged, realizing the operability of the battery stack in the SOC range of nearly 0-100%, effectively improving the capacity of the battery stack energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the first structure of a battery stack energy storage system provided in an embodiment of the present application;

[0033] Figure 2 A second structural schematic diagram of a battery stack energy storage system provided in an embodiment of the present application;

[0034] Figure 3 A third structural schematic diagram of a battery stack energy storage system provided in an embodiment of the present application;

[0035] Figure 4 A first overview flow chart of the battery stack control method provided in an embodiment of the present application;

[0036] Figure 5 A second overview flow chart of the battery stack control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and beneficial effects of this application clearer, the technical solution in the embodiment of this application will be clearly and completely described below in conjunction with the drawings in the embodiment of this application. Obviously, the described embodiment is only a part of the embodiment of this application, not all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] First, the application scenarios and design concepts of the embodiments of the present application are briefly introduced.

[0039] At present, for large-capacity high-voltage energy storage systems in which multiple battery clusters are directly connected in parallel to a tower PCS architecture, in actual operation, the so-called "short board effect" is caused by inherent manufacturing differences, inconsistent charging and discharging characteristics, and different aging rates between the battery clusters. Specifically, when multiple battery clusters work in parallel, the battery cluster with the worst performance will determine the available capacity and charging and discharging efficiency of the entire battery stack. Over time, this difference will further intensify, causing the overall performance of the system to gradually decline, the available capacity to decrease, and the operating efficiency to decrease. In addition, when multiple battery clusters are directly connected in parallel, if full charge or full discharge operations are to be achieved, measures must be taken for the battery cluster that reaches the limit state first, such as tripping the contactor to disconnect it from the system. However, frequent load operations under full charge and discharge conditions for a long time will cause the life of the electrical switch to be drastically shortened, and once a battery cluster is decoupled, the available power provided to the outside by the entire battery stack will also be reduced accordingly. Under existing technical conditions, how to effectively overcome a series of problems caused by the short board effect between battery clusters has become one of the key challenges to improving the performance of large-capacity high-voltage energy storage systems.

[0040] To this end, the present application sets a parallel-connected energy storage control unit and a charge and discharge control unit between the positive output terminal of each battery cluster and the positive DC bus, and when the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism, controls the battery cluster to be connected to the positive DC bus through the energy storage control unit. The energy storage control unit itself has the function of isolating DC power and connecting AC power, which can not only effectively prevent overcharging and over-discharging of the battery cluster, but also provide protection for the safety of the battery cluster. Moreover, the online coupling of the battery cluster can be realized to improve the available power of the battery stack energy storage system. In addition, after each battery cluster in the battery stack is fully charged or completely discharged, it is connected to the positive DC bus through the energy storage control unit, and all the battery clusters in the battery stack can be fully charged and discharged, realizing the operability of the battery stack in the SOC range of nearly 0-100%, effectively improving the capacity of the battery stack energy storage system.

[0041] After introducing the application scenarios and design concepts of the embodiments of the present application, the technical solutions provided by the embodiments of the present application are described in detail below.

[0042] The present application embodiment provides a battery stack energy storage system, see Figure 1 As shown, the battery stack energy storage system 100 provided in the embodiment of the present application comprises at least: a battery stack 120 composed of at least two battery clusters 110 , a power distribution unit 130 corresponding to each battery cluster 110 , and a battery management system 140 ;

[0043] The negative output terminal of each battery cluster 110 is connected to the negative DC bus, and the positive output terminal of each battery cluster 110 is connected to the positive DC bus via the power distribution unit 130; each power distribution unit 130 includes an energy storage control unit 131 and a charge and discharge control unit 132 connected in parallel;

[0044] The battery management system 140 is respectively connected to each battery cluster 110 and the energy storage control unit 131 and the charge and discharge control unit 132 in the power distribution unit 130 corresponding to each battery cluster 110;

[0045] For each battery cluster 110, when the battery cluster 110 meets the triggering conditions of the full charge and discharge protection mechanism, after the energy storage control unit 131 corresponding to the battery cluster 110 is switched from the disconnected state to the connected state, the charge and discharge control unit 132 corresponding to the battery cluster 110 is switched from the connected state to the disconnected state, so that the energy storage control unit 131 keeps the battery cluster 110 in an online coupling state through energy storage.

[0046] exist Figure 1In the battery stack energy storage system 100 shown, the battery cluster 110 is composed of battery cells connected in series, in parallel, or in a mixed manner of series and parallel. The battery management system 140 can detect, monitor, and manage each battery cluster 110 in the battery stack energy storage system 100. Each battery cluster 110 in the battery stack energy storage system 100 is connected in parallel to the DC bus, and the other end of the DC bus is connected to the PCS. The negative output end of each battery cluster 110 is connected to the negative DC bus, and the battery management system 140 controls the energy storage control unit 131 or the charge and discharge control unit 132 connected to the positive output end of each battery cluster 110 to be turned on to achieve the coupling between the battery cluster 110 and the DC bus under different working conditions. When the battery cluster 110 is in a normal charge and discharge state or in a standby state, the battery management system 140 controls the circuit connection of the charge and discharge control unit 132 to be turned on, and the positive output end of the battery cluster 110 is coupled to the positive DC bus through the charge and discharge control unit 132. When the battery cluster 110 is in a full charge and discharge protection state or a power-on abnormal state, the battery management system 140 controls the circuit connection of the energy storage control unit 131, and the positive output terminal of the battery cluster 110 is coupled to the positive DC bus through the energy storage control unit 131, wherein the full charge and discharge protection state refers to a state in which the battery cluster 110 is fully charged to a maximum power and the battery cluster 110 is still in a charging mode, or a state in which the battery cluster 110 is fully discharged to a minimum power and the battery cluster 110 is still in a discharging mode.

[0047] Specifically, the full charge and discharge protection mechanism means that after the battery management system 140 controls the energy storage control unit 131 corresponding to the battery cluster 110 to switch from the disconnected state to the connected state, the charge and discharge control unit 132 corresponding to the battery cluster 110 is controlled to switch from the connected state to the disconnected state. The triggering condition of the full charge and discharge protection mechanism means that the current state of charge data and the current working state data of the battery cluster 110 are within the corresponding state of charge data range and the corresponding working state data range of the full charge and discharge protection state. When any battery cluster 110 in the battery stack energy storage system 100 meets the triggering conditions of the full charge and discharge protection mechanism, the battery management system 140 is automatically triggered to first connect the circuit connection of the energy storage control unit 131, and then disconnect the circuit connection of the originally connected charge and discharge control unit 132, that is, when each battery cluster 110 in the battery stack energy storage system 100 is fully charged to the maximum power and in the charging mode, or fully discharged to the minimum power and in the discharge mode, it is connected to the positive DC bus through the energy storage control unit 131, and all battery clusters 110 in the battery stack 120 can be fully charged and discharged, thereby realizing the operability of the battery stack 120 in the SOC range of nearly 0-100%, effectively improving the capacity of the battery stack energy storage system 100. Since the energy storage element in the energy storage control unit 131 can isolate direct current and connect alternating current, when the battery cluster 110 meets the triggering condition of the full charge and discharge protection mechanism, the battery cluster 110 is coupled to the direct current bus through the energy storage control unit 131, and the direct current between the battery cluster 110 and the direct current bus is isolated by the energy storage control unit 131. Specifically, when the battery cluster 110 is fully charged to the maximum power and in the charging mode, the bus voltage between the positive direct current bus and the negative direct current bus rises to charge all the battery clusters 110, and the battery cluster 110 connected to the fully charged battery cluster 110 is charged to the maximum power. The energy control unit 131 can store the energy transmitted by the DC bus to compensate for the voltage difference between the battery cluster 110 fully charged to the maximum power and the positive DC bus; when the battery cluster 110 is fully discharged to the minimum power and in the discharge mode, the energy storage control unit 131 connected to the battery cluster 110 fully discharged to the minimum power can store the energy transmitted by the connected battery cluster 110 to compensate for the voltage difference between the battery cluster 110 fully discharged to the minimum power and the positive DC bus, effectively preventing overcharging and overdischarging of the battery cluster 110, and providing protection for the safety of the battery cluster 110. In addition, compared with the solution in the prior art that when multiple groups of battery clusters 110 are directly connected in parallel, if full charging or full discharging operations are to be achieved, the battery cluster 110 that reaches the limit state first must be disconnected from the system, the battery cluster 110 that reaches the limit state can be kept connected to the DC bus by turning on the energy storage control unit 131, so as to achieve online coupling of the battery cluster 110 and improve the available power of the battery stack energy storage system 100.

[0048] In addition, for each battery cluster 110 in the battery stack energy storage system 100, the battery cluster 110 cannot meet the safe power-on condition in the power-on abnormal state, and the safe power-on condition means that the difference between the output voltage of the battery cluster 110 and the bus voltage is less than the voltage difference threshold. When the battery cluster 110 cannot meet the safe power-on condition, the battery management system 140 is automatically triggered to first connect the circuit connection of the energy storage control unit 131, until it is detected that the battery cluster 110 meets the safe power-on condition, and then control the connection of the circuit connection of the charge and discharge control unit 132 corresponding to the battery cluster 110, and control the disconnection of the circuit connection of the energy storage control unit 131 corresponding to the battery cluster 110. Since some energy is stored in the energy storage element of the energy storage control unit 131, when the battery cluster 110 cannot meet the safe power-on condition, after the energy storage control unit 131 is turned on, if the battery cluster 110 is the first battery cluster 110 in the battery stack energy storage system 100, the energy storage control unit 131 can charge the DC bus to make the difference between the output voltage of the battery cluster 110 and the bus voltage reach the voltage difference threshold. At this time, the battery cluster 110 meets the safe power-on condition, and the battery management system 140 controls the circuit connection of the charge and discharge control unit 132 corresponding to the battery cluster 110 to be turned on, and controls the circuit connection of the energy storage control unit 131 corresponding to the battery cluster 110 to be turned off, so as to realize the power-on of the corresponding battery cluster 110. If the battery cluster 110 is not the first battery cluster 110 in the battery stack energy storage system 100, the energy storage control unit 131 can only realize the coupling of the battery cluster 110 to the DC bus. When the bus voltage changes so that the battery cluster 110 meets the safe power-on condition, the battery management system 140 controls the circuit connection of the charge and discharge control unit 132 corresponding to the battery cluster 110 to be connected, and controls the circuit connection of the energy storage control unit 131 corresponding to the battery cluster 110 to be disconnected, so as to realize the power-on of the corresponding battery cluster 110. In this way, by setting the safe power-on condition, the system can perform a safety assessment before the battery cluster 110 is powered on, effectively avoiding the current shock, equipment damage and safety accidents that may be caused by excessive voltage differences. In addition, the battery management system 140 is automatically triggered to connect the circuit connection of the energy storage control unit 131 first, ensuring that when the safe power-on condition is not met, the system can take pre-power-on measures, and perform voltage adjustment or energy buffering through the energy storage control unit 131 to create conditions for the safe power-on of the battery cluster 110.

[0049] In specific implementation, the energy storage control unit in the power distribution unit can have a variety of structures to achieve its functions, see Figure 2 As shown, the energy storage control unit 131 may specifically include: a resistor R, an energy storage capacitor C1 and a first controllable switch K1 connected in series; the control end of the first controllable switch K1 is connected to the battery management system 140 .

[0050] exist Figure 2In the battery stack energy storage system 100 shown, the resistor R is used to adjust the current flowing through the energy storage control unit 131. The energy storage capacitor C1 is used to store and release energy, and is also used to isolate the direct current between the battery cluster 110 and the DC bus. The energy storage capacitor C1 can be composed of one capacitor, or it can be composed of multiple capacitors connected in series, in parallel, or in a combination of series and parallel. The first controllable switch K1 is used to connect or disconnect the circuit connection of the energy storage control unit 131 under the control of the battery management system 140.

[0051] In specific implementation, the charge and discharge control unit in the power distribution unit can have a variety of structures to achieve its functions, see Figure 2 As shown, the charge and discharge control unit 132 may specifically include: a second controllable switch K2 ; a control end of the second controllable switch K2 is connected to the battery management system 140 .

[0052] exist Figure 2 In the battery stack energy storage system 100 shown, the second controllable switch K2 is used to connect or disconnect the circuit connection of the charge and discharge control unit 132 under the control of the battery management system 140. The second controllable switch K2 can be used as a charge and discharge protection switch for the battery cluster 110, which simplifies the system structure and reduces the system cost compared with the existing method in which a controllable switch is provided between the negative output terminal of each battery cluster 110 and the negative DC bus, and between the positive output terminal of each battery cluster 110 and the positive DC bus.

[0053] In one possible implementation, see Figure 3 As shown, the battery stack energy storage system 100 also includes: a bus capacitor C2; the bus capacitor C2 is connected between the positive DC bus and the negative DC bus; the capacitance of the bus capacitor C2 is smaller than the capacitance of the energy storage capacitor C1.

[0054] exist Figure 3 In the battery stack energy storage system 100 shown, in order to realize that when the battery cluster 110 cannot meet the safe power-on conditions, the energy storage control unit 131 connected to the first battery cluster 110 in the battery stack energy storage system 100 can charge the bus capacitor C2 to a steady-state voltage, so that the difference between the output voltage of the battery cluster 110 and the bus voltage is less than the voltage difference threshold, the capacitance of the bus capacitor C2 needs to be less than the capacitance of the energy storage capacitor C1. In the actual setting process, it is generally required that: the steady-state voltage of the bus capacitor C2 ≥ 0.8 * battery cluster voltage, in order to realize charging the capacitor voltage of the bus capacitor C2 to a steady-state voltage, according to the voltage division principle of the resistor R and the energy storage capacitor C1 connected in series in the energy storage control unit 131, it can be set that: 25% * the capacitance of the energy storage capacitor C1 ≥ the capacitance of the bus capacitor C2.

[0055] In one possible implementation, see Figure 3As shown, the battery stack energy storage system 100 also includes: a power-on control unit 150 corresponding to each battery cluster 110; the negative output terminal of each battery cluster 110 is connected to the negative DC bus via the power-on control unit 150, and the positive output terminal of each battery cluster 110 is connected to the positive DC bus via the power-on control unit 150 and the power distribution unit 130 in turn.

[0056] exist Figure 3 In the battery stack energy storage system 100 shown, the power-on control unit can be composed of a circuit breaker. The circuit breaker QF1 is arranged between the negative output terminal of the corresponding battery cluster 110 and the negative DC bus. The circuit breaker QF1 is also arranged between the positive output terminal of the corresponding battery cluster 110 and the power distribution unit 130. The circuit breaker QF1 needs to be closed manually. Before executing the power-on operation of the battery cluster 110, first, the circuit breaker corresponding to the battery cluster 110 needs to be manually closed. Then, after the battery management system 140 detects that the circuit breaker is closed, it detects the output voltage and output current of the battery cluster 110. When the output voltage of the battery cluster 110 is within the rated output voltage range of the battery cluster 110, and the output current of the battery cluster 110 is within the rated output current range of the battery cluster 110, it is determined that the battery cluster 110 has no abnormality, and the power-on operation of the battery cluster 110 is executed; if the output voltage of the battery cluster 110 is not within the rated output voltage range of the battery cluster 110, or, when the output current of the battery cluster 110 is not within the rated output current range of the battery cluster 110, it is determined that the battery cluster 110 is abnormal, and at this time, an abnormal alarm of the battery cluster 110 is issued.

[0057] Based on the same inventive concept, a battery stack control method is also provided in the embodiment of the present application, see Figure 4 As shown, in the battery management system applied to the above-mentioned battery stack energy storage system, the overview process of the battery stack control method provided in the embodiment of the present application is as follows:

[0058] Step 401: Acquire first power status data of each battery cluster in a battery stack energy storage system.

[0059] In actual applications, the first power status data includes current state of charge data and current working status data. The current state of charge data reflects the power level of the battery cluster, that is, the percentage of the power currently stored in the battery cluster to its total power. The battery management system includes sensors arranged at the location of each battery cluster for collecting current state of charge data according to a preset collection cycle. Specifically, the sensor may be a voltage sensor and a current sensor. The battery management system may calculate the current state of charge data based on the data collected by the voltage sensor and the current sensor. The current working status data is used to indicate whether the battery cluster is currently in a charging mode or a discharging mode. The battery management system may send relevant instructions to the battery cluster to receive the current working status data fed back by the battery cluster, or determine the current working status data of the battery cluster based on the change of the state of charge data of the battery cluster within a preset time.

[0060] Step 402: Based on the first power status data of each battery cluster, detect whether each battery cluster meets the triggering condition of the full charge and discharge protection mechanism.

[0061] In practical applications, for each battery cluster, it is necessary to detect whether the triggering condition of the full charge, discharge and protection mechanism is met based on its first power state data. The triggering condition of the full charge, discharge and protection mechanism refers to the first power state data of the battery cluster being within the variation range of the first power state data of the corresponding full charge, discharge and protection state. The full charge, discharge and protection state refers to the state in which the battery cluster is fully charged to the maximum power and the battery cluster is still in the charging mode, or the state in which the battery cluster is fully discharged to the minimum power and the battery cluster is still in the discharging mode.

[0062] Specifically, based on the first power status data of each battery cluster, it is detected whether each battery cluster meets the triggering condition of the full charge and discharge protection mechanism, which can be implemented in but not limited to the following ways:

[0063] For each battery cluster, if it is detected based on the current working status data of the battery cluster that the battery cluster is in charging mode, and based on the current charge state data of the battery cluster that the battery cluster is in full charge state, then it is determined that the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism; if it is detected based on the current working status data of the battery cluster that the battery cluster is in discharging mode, and based on the current charge state data of the battery cluster that the battery cluster is in full discharge state, then it is determined that the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism.

[0064] In practical applications, the current working state data of the battery cluster can be in binary form of 0 or 1, 0 can represent the discharge mode, and 1 can represent the charge mode. The current state of charge data of the battery cluster can be in the form of percentage, and the value range is usually 0% to 100%, 0% means that the battery is in a fully discharged state, and 100% means that the battery is in a fully charged state. For each battery cluster, if the current working state data of the battery cluster is 1, it is detected that the battery cluster is in the charge mode, and the current state of charge data of the battery cluster is 100%, it is detected that the battery cluster is in a fully charged state, then it is determined that the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism; if the current working state data of the battery cluster is 0, it is detected that the battery cluster is in the discharge mode, and the current state of charge data of the battery cluster is 0%, it is detected that the battery cluster is in a fully discharged state, then it is determined that the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism.

[0065] Step 403: when it is detected that any battery cluster meets the triggering condition of the full charge and discharge protection mechanism, the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be connected, and then the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be disconnected.

[0066] In practical applications, when any battery cluster meets the triggering conditions of the full charge and discharge protection mechanism, the battery management system is automatically triggered to execute the full charge and discharge protection mechanism. Specifically, when each battery cluster in the battery stack is in the charging mode, there is any battery cluster that meets the triggering conditions of the full charge and discharge protection mechanism. The battery management system first connects the circuit connection of the energy storage control unit of the battery cluster, and then disconnects the circuit connection of the charge and discharge control unit that was originally connected. At this time, the battery cluster is connected to the positive DC bus through the energy storage control unit. The voltage of the DC bus continues to rise to charge other battery clusters that are not fully charged until the full charge and discharge protection mechanism of all battery clusters is completed, and the battery stack is fully charged. Correspondingly, when each battery cluster in the battery stack is in the discharge mode, there is any battery cluster that meets the triggering conditions of the full charge and discharge protection mechanism. The battery management system first connects the circuit connection of the energy storage control unit of the battery cluster, and then disconnects the circuit connection of the charge and discharge control unit that was originally connected. At this time, the battery cluster is connected to the positive DC bus through the energy storage control unit until the full charge and discharge protection mechanism of all battery clusters is completed, and the battery stack is fully discharged. In this way, the operability of the battery stack in the SOC range of nearly 0-100% is achieved, and the capacity of the battery stack energy storage system is effectively improved. When the battery cluster is fully charged to the maximum power and in the charging mode, the bus voltage between the positive DC bus and the negative DC bus rises to charge all the battery clusters, and the energy storage control unit connected to the battery cluster fully charged to the maximum power can store the energy transmitted by the DC bus to make up for the voltage difference between the battery cluster fully charged to the maximum power and the positive DC bus; when the battery cluster is fully discharged to the minimum power and in the discharge mode, the energy storage control unit connected to the battery cluster fully discharged to the minimum power can store the energy transmitted by the connected battery cluster to make up for the voltage difference between the battery cluster fully discharged to the minimum power and the positive DC bus, effectively preventing overcharging and overdischarging of the battery cluster, and providing protection for the safety of the battery cluster. In addition, compared with the prior art solution that must disconnect the battery cluster that reaches the limit state first from the system, the battery cluster that reaches the limit state can be connected to the DC bus by connecting the energy storage control unit to achieve online coupling of the battery cluster and improve the available power of the battery stack energy storage system.

[0067] In one possible implementation, see Figure 5 As shown, before obtaining the first power state data of each battery cluster in the battery stack energy storage system, it also includes:

[0068] Step 501: Acquire second power status data of each battery cluster;

[0069] In practical applications, the second power state data includes the difference between the output voltage of the battery cluster and the bus voltage. The battery management system also includes a sensor disposed at the location of the positive DC bus and the negative DC bus for collecting the bus voltage according to a preset collection cycle. Specifically, the sensor may be a voltage sensor. The battery management system may calculate the difference between the output voltage of the battery cluster and the bus voltage based on the output voltage of the battery cluster and the bus voltage.

[0070] Step 502: Based on the second power status data of each battery cluster, detect whether each battery cluster meets the safety power-on condition.

[0071] In practical applications, in order to ensure the safety of the battery stack energy storage system and avoid overcurrent protection of the battery stack energy storage system caused by a large difference between the output voltage of the battery cluster and the bus voltage of the DC bus, it is necessary to detect whether each battery cluster meets the safe power-on conditions based on the second power status data of each battery cluster before the battery cluster is powered on.

[0072] Specifically, based on the second power status data of each battery cluster, detecting whether each battery cluster meets the safe power-on condition may be performed in the following manners, but not limited to:

[0073] For each battery cluster, if the difference between the output voltage of the battery cluster and the bus voltage is detected to be less than the voltage difference threshold, it is determined that the battery cluster meets the safe power-on conditions; if the difference between the output voltage of the battery cluster and the bus voltage is detected to be greater than or equal to the voltage difference threshold, it is determined that the battery cluster does not meet the safe power-on conditions.

[0074] In practical applications, the voltage difference threshold is determined based on the impedance of the battery cluster in the battery stack energy storage system and the voltage tolerance of all devices used in the electrical circuit of the battery stack energy storage system. The voltage difference threshold A needs to satisfy: A / impedance of the battery cluster ≤ voltage tolerance of all devices in the electrical circuit.

[0075] Step 503: When it is detected that any battery cluster does not meet the safe power-on conditions, control the circuit connection of the energy storage control unit corresponding to the battery cluster to be connected, until it is detected that the battery cluster meets the safe power-on conditions, control the circuit connection of the charge and discharge control unit corresponding to the battery cluster to be connected, and control the circuit connection of the energy storage control unit corresponding to the battery cluster to be disconnected.

[0076] In actual applications, when it is detected that any battery cluster does not meet the safe power-on conditions, the pre-power-on operation corresponding to the power-on sequence of the battery cluster is performed according to the power-on sequence of the battery cluster. After the corresponding pre-power-on operation is completed, when the battery management system detects that the battery cluster meets the safe power-on conditions, it controls the second controllable switch in the charge and discharge control unit corresponding to the battery cluster to be turned on, and controls the first controllable switch in the energy storage control unit corresponding to the battery cluster to be turned off. In this way, by obtaining the second power status data of the battery cluster, the voltage matching between the battery cluster and the busbar is monitored in real time, and whether the battery cluster meets the safe power-on conditions is detected, which effectively avoids the overcurrent protection triggering or equipment damage caused by excessive voltage difference, thereby significantly improving the safety of the system.

[0077] Specifically, when it is detected that any battery cluster does not meet the safe power-on condition, a pre-power-on operation corresponding to the power-on sequence of the battery cluster is performed according to the power-on sequence of the battery cluster, which can be divided into the following two situations:

[0078] The first case: the battery cluster that does not meet the safety power-on condition is the first battery cluster in the battery stack energy storage system. In the first case, before the battery management system controls the circuit connection of the charge and discharge control unit corresponding to the battery cluster, it also includes:

[0079] A capacitor voltage of a bus capacitor connected between a positive DC bus and a negative DC bus is obtained, and it is determined that the capacitor voltage of the bus capacitor reaches a steady-state voltage.

[0080] In actual applications, the battery cluster is the first battery cluster. After the battery management system controls the circuit connection of the energy storage control unit corresponding to the battery cluster, the energy storage control unit is connected to the positive DC bus. At this time, the energy storage control unit charges the bus capacitor connected between the positive DC bus and the negative DC bus to charge the capacitor voltage of the bus capacitor connected between the positive DC bus and the negative DC bus to a steady-state voltage. After the capacitor voltage of the bus capacitor reaches the steady-state voltage, the battery management system controls the circuit connection of the charge and discharge control unit corresponding to the battery cluster.

[0081] The second case: the battery cluster that does not meet the safety power-on condition is not the first battery cluster in the battery stack energy storage system. In the second case, the battery management system directly controls the circuit connection of the energy storage control unit corresponding to the battery cluster.

[0082] In actual applications, the battery cluster is not the first battery cluster, and the battery management system controls the circuit connection of the energy storage control unit corresponding to the battery cluster. During the charging or discharging process of the battery stack energy storage system, the bus voltage will change. During the bus voltage change, if it is detected that the difference between the output voltage of the battery cluster and the bus voltage is less than the voltage difference threshold, the second controllable switch in the charge and discharge control unit corresponding to the battery cluster is controlled to be turned on, and then the first controllable switch in the energy storage control unit corresponding to the battery cluster is controlled to be turned off.

[0083] In this way, for the first battery cluster, by charging the bus capacitor to a steady-state voltage, the stability of the bus voltage is ensured when the battery cluster is connected, further improving the safety of the power-on process. For non-first battery clusters, the circuit connection of the energy storage control unit is directly controlled, and the charge and discharge control unit is connected in time when the bus voltage changes, realizing flexible control of the battery cluster. In addition, the control strategy is automatically adjusted according to different battery cluster states and bus voltage conditions, reflecting good adaptability and flexibility.

[0084] In a possible implementation manner, the process of detecting whether each battery cluster meets the safe power-on condition based on the second power state data of each battery cluster further includes:

[0085] When it is detected that any battery cluster meets the safe power-on condition, the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be connected, and the circuit connection of the energy storage control unit corresponding to the battery cluster is kept disconnected.

[0086] In actual applications, when it is detected that any battery cluster meets the safe power-on conditions, it means that directly connecting to the battery cluster will not cause safety issues affecting the battery stack energy storage system. At this time, the circuit connection of the charge and discharge control unit corresponding to the battery cluster can be directly controlled to power on the battery cluster, which simplifies the power-on process and improves operating efficiency.

[0087] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0088] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0089] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0090] It should be noted that if the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can essentially be embodied in the form of a software product, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM) random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0091] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0092] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery stack energy storage system, characterized in that: include: A battery stack consisting of at least two battery clusters, a power distribution unit corresponding to each of the battery clusters, and a battery management system; The negative output terminal of each battery cluster is connected to the negative DC bus, and the positive output terminal of each battery cluster is connected to the positive DC bus via the power distribution unit; each power distribution unit includes an energy storage control unit and a charge and discharge control unit connected in parallel; The battery management system is respectively connected to each of the battery clusters and the energy storage control unit and the charge and discharge control unit in the power distribution unit corresponding to each of the battery clusters; For each of the battery clusters, when the battery cluster meets the triggering conditions of the full charge and discharge protection mechanism, after the energy storage control unit corresponding to the battery cluster is switched from the disconnected state to the connected state, the charge and discharge control unit corresponding to the battery cluster is switched from the connected state to the disconnected state, so that the energy storage control unit keeps the battery cluster in an online coupling state through energy storage.

2. The battery stack energy storage system according to claim 1, characterized in that: The energy storage control unit comprises: a resistor, an energy storage capacitor and a first controllable switch connected in series; a control end of the first controllable switch is connected to the battery management system.

3. The battery stack energy storage system according to claim 1, characterized in that: The charge and discharge control unit includes: a second controllable switch; a control end of the second controllable switch is connected to the battery management system.

4. The battery stack energy storage system according to claim 2, characterized in that: Also includes: Bus capacitor; the bus capacitor is connected between the positive DC bus and the negative DC bus, and the capacitance of the bus capacitor is smaller than the capacitance of the energy storage capacitor.

5. A battery stack control method, characterized in that: A battery management system applied to a battery stack energy storage system as claimed in any one of claims 1 to 4, comprising: Acquiring first power status data of each battery cluster in the battery stack energy storage system; Based on the first power status data of each of the battery clusters, detecting whether each of the battery clusters meets a triggering condition of a full charge and discharge protection mechanism; When it is detected that any of the battery clusters meets the triggering condition of the full charge and discharge protection mechanism, the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be connected, and then the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be disconnected.

6. The battery stack control method according to claim 5, characterized in that: The first power status data includes current charge status data and current working status data; based on the first power status data of each battery cluster, detecting whether each battery cluster meets the triggering condition of the full charge and discharge protection mechanism includes: For each battery cluster, if it is detected based on the current working status data of the battery cluster that the battery cluster is in a charging mode, and based on the current charge state data of the battery cluster that the battery cluster is in a fully charged state, then it is determined that the battery cluster meets the triggering condition of the full charge and discharge protection mechanism; if it is detected based on the current working status data of the battery cluster that the battery cluster is in a discharging mode, and based on the current charge state data of the battery cluster that the battery cluster is in a fully discharged state, then it is determined that the battery cluster meets the triggering condition of the full charge and discharge protection mechanism.

7. The battery stack control method according to claim 5 or 6, characterized in that: Before obtaining the first power state data of each battery cluster in the battery stack energy storage system, the method further includes: acquiring second power status data of each of the battery clusters; Based on the second power status data of each of the battery clusters, detecting whether each of the battery clusters meets a safe power-on condition; When it is detected that any of the battery clusters does not meet the safe power-on condition, the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be connected, until it is detected that the battery cluster meets the safe power-on condition, the circuit connection of the charging and discharging control unit corresponding to the battery cluster is controlled to be connected, and the circuit connection of the energy storage control unit corresponding to the battery cluster is controlled to be disconnected.

8. The battery stack control method according to claim 7, characterized in that: The second power status data includes a difference between an output voltage of the battery cluster and a bus voltage; Based on the second power status data of each of the battery clusters, detecting whether each of the battery clusters meets the safe power-on condition includes: For each of the battery clusters, if it is detected that the difference between the output voltage of the battery cluster and the bus voltage is less than a voltage difference threshold, it is determined that the battery cluster meets the safe power-on condition; If it is detected that the difference between the output voltage of the battery cluster and the bus voltage is greater than or equal to the voltage difference threshold, it is determined that the battery cluster does not meet the safe power-on condition.

9. The battery stack control method according to claim 7, characterized in that: If the battery cluster that does not meet the safety power-on condition is the first battery cluster in the battery stack energy storage system, before controlling the circuit connection of the charge and discharge control unit corresponding to the battery cluster, the method further includes: A capacitor voltage of a bus capacitor connected between a positive DC bus and a negative DC bus is obtained, and it is determined whether the capacitor voltage of the bus capacitor reaches a steady-state voltage.

10. The battery stack control method according to claim 7, characterized in that: The process of detecting whether each of the battery clusters meets the safety power-on condition based on the second power state data of each of the battery clusters further includes: When it is detected that any of the battery clusters meets the safety power-on condition, the circuit connection of the charge and discharge control unit corresponding to the battery cluster is controlled to be connected, and the circuit connection of the energy storage control unit corresponding to the battery cluster is kept disconnected.

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