Insulation detection method for an energy storage system

Abstract

The application discloses an insulation detection method of an energy storage system and belongs to the technical field of intelligent energy storage systems. The application applies time-sharing insulation detection and time-sharing insulation detection of a timing round-robin through a battery cluster management unit BCU, and insulation detection is completed through mutual cooperation and coordination of the cluster level. The mechanism does not rely on a higher-level battery stack management unit BAU to coordinate insulation detection functions. Even if the battery stack management unit BAU or a certain battery cluster management unit BCU is out of connection, the insulation detection function of the whole system is not affected. Through arbitration of insulation detection priority and the timing round-robin insulation detection mechanism, it is ensured that only one battery cluster is performing insulation detection at a certain moment, and the battery cluster with insulation failure and the insulation failure details are accurately located and understood, so that the insulation of each battery cluster does not interfere with each other, the insulation safety of the whole energy storage battery system is ensured in real time, and the reliability, stability and safety of the whole energy storage system operation are improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of intelligent energy storage systems, and particularly relates to an insulation detection method for an energy storage system. BACKGROUND

[0002] With the rapid development of power energy storage systems, the energy storage battery system contains batteries, battery leakage and the risk of positive and negative electrode insulation damage, which causes excessive system leakage current and risks. Industrial and commercial and large energy storage container energy storage battery systems generally adopt a multi-cluster battery cluster parallel common DC bus system scheme. In this application scenario, as the system cluster size increases, the system insulation becomes more complex. How to accurately locate the position of the entire energy storage system insulation fault and avoid the risk of large current caused by the low positive and negative electrode insulation impedance of the entire system DC bus to the ground is a key problem that needs to be considered from a technical point of view.

[0003] Therefore, it is necessary to adopt a suitable detection method for insulation detection of the energy storage battery system in this application scenario to meet the insulation detection needs of industrial and commercial and large energy storage battery systems. It is particularly important to think about and solve how to provide an insulation detection method that can effectively perform insulation detection on the entire system, ensure that the insulation of each battery cluster does not interfere with each other, ensure the real-time insulation safety of the entire energy storage battery system, accurately locate the position of the insulation abnormal battery cluster insulation fault, and improve the reliability, stability and safety of the entire energy storage battery system. SUMMARY

[0004] To solve the existing technical problems, the application provides an insulation detection method for an energy storage system, wherein the energy storage system comprises at least two battery clusters connected in parallel with each other, each battery cluster has an independent number, and the battery clusters have different priority orders, and the priority order is the same as the order of the battery clusters. The battery cluster is composed of series and parallel connection of battery modules, each battery cluster is provided with a battery management system BMS and a high-voltage box, the battery management system BMS comprises at least one battery stack management unit BAU, the battery stack management unit BAU coordinates and manages at least two battery cluster management units BCU, and the battery cluster management unit BCU coordinates and manages at least one battery module unit BMU. The battery cluster further comprises an insulation detection module, and each battery cluster is connected to and matched with the insulation detection module.

[0005] Preferably or optionally, the battery management system BMS, the battery stack management unit BAU and the battery cluster management unit BCU are connected through the same link to form a cluster communication.

[0006] Preferably or optionally, the battery clusters communicate with each other through the communication link and match the cluster communication protocol, each battery cluster can send its insulation-related information message to the battery stack management unit BAU through the communication link, and can also send its insulation-related information to other battery cluster management units BCU in the system through the communication link, so as to realize information exchange between each battery cluster management unit BCU in the whole system.

[0007] Preferably or optionally, the communication interaction mode includes RS485, CAN, CAN-FD, and Ethernet communication.

[0008] Preferably or optionally, the high-voltage box includes a high-voltage circuit, an insulation detection module, and a relay program-controlled switch execution unit, the relay program-controlled switch execution unit has a direct-current high-voltage closing and opening control function; the battery cluster management unit BCU is matched and bound with the high-voltage circuit and the insulation detection module, and the battery cluster management unit BCU can control the insulation detection module to open or close the insulation detection function.

[0009] An insulation detection logic of an energy storage system includes the following steps:

[0010] I. All battery cluster management units BCU open the insulation detection function before high-voltage closing, realize the synchronous opening of cluster insulation detection, and determine whether the cluster has insulation failure, if there is insulation failure, report the cluster insulation failure to the battery stack control unit BAU through the BCU, and the battery cluster control unit BCU prohibits the cluster high-voltage closing;

[0011] II. After determining the insulation failure of the battery cluster, the battery cluster management unit BCU reports the insulation failure information to the battery stack control unit BAU, and accurately locates the insulation failure position of the battery cluster; after confirming that the battery cluster has no insulation failure, the battery cluster with normal insulation waits to receive the high-voltage closing instruction from the battery stack management unit BAU to perform the high-voltage action of the battery cluster, and the battery cluster with normal insulation receives the high-voltage closing instruction from the battery stack management unit BAU, then enters the high-voltage closing insulation detection logic of the system battery cluster, and the battery cluster with normal insulation does not receive the high-voltage closing instruction from the battery stack management unit BAU, then is in a state of waiting for the high-voltage instruction;

[0012] III. After high voltage on the battery cluster with normal insulation, the battery cluster management unit BCU receives the high voltage opening command from the battery stack management unit BAU to perform the battery cluster high voltage action. The battery cluster control unit BCU receiving the command determines whether it is in the insulation detection state. If the battery cluster management unit BCU receiving the command is in insulation detection, the battery cluster management unit BCU informs other battery clusters and then performs the high voltage opening action. Other battery clusters without power perform arbitration mechanism to compete for insulation detection priority arbitration. The insulation detection switching process realizes time-sharing insulation detection. If the battery cluster control unit BCU receiving the command is not in insulation detection, other battery clusters without power perform time-sharing insulation detection by timing round robin.

[0013] Preferably or optionally, the switching process of time-sharing insulation detection in step III is: when all battery clusters in the energy storage system are in the high voltage closing normal operation process, if the battery cluster system cluster communication line is disconnected or the cluster closing / opening action is required, the arbitration mechanism is performed once. The system performs the battery cluster insulation detection opening action according to the priority from high to low, and then normally rounds the insulation detection. The arbitration order is from small to large according to the battery cluster ID for insulation detection priority allocation. The smaller the battery cluster ID, the higher the priority. The battery clusters are opened one by one according to the priority from high to low.

[0014] Preferably or optionally, the switching process of time-sharing insulation detection in step III is: when all battery clusters in the energy storage system are in the high voltage closing normal operation process, if the battery cluster system cluster communication line is disconnected or the cluster closing / opening action is required, the arbitration mechanism is performed once. The system performs the battery cluster insulation detection opening action according to the priority from high to low, and then normally rounds the insulation detection. The arbitration order is from small to large according to the battery cluster ID for insulation detection priority allocation. The smaller the battery cluster ID, the higher the priority. The battery clusters are opened one by one according to the priority from high to low.

[0015] Preferably or optionally, the time interval is 1 minute. If the battery cluster insulation fault or the battery cluster communication interruption occurs within the insulation detection interval time, the cluster exits the time-sharing insulation detection by timing round robin. Other battery clusters with normal insulation perform arbitration once and then switch to time-sharing insulation detection by timing round robin. The insulation detection is opened according to the time interval of 1 minute, and the insulation detection is closed after the insulation detection.

[0016] Beneficial effects: the application applies an insulation detection logic in the energy storage system, and the insulation detection logic strategy includes time-sharing insulation detection and timing round robin time-sharing insulation detection. Each battery cluster of the application has a separate insulation detection function, and the insulation detection logic algorithm applied in the cluster storage battery system through the battery cluster management unit BCU can realize real-time online detection function of each cluster insulation fault in the whole energy storage battery system. The application forms a cluster communication among the battery management system BMS, the battery stack management unit BAU and the battery cluster management unit BCU, and communicates with each other through the matching cluster communication protocol on the built communication link between the battery clusters, so that each cluster knows the insulation state of each cluster. The insulation detection is completed by the battery cluster management unit BCU at the cluster level, and the insulation detection function is not coordinated by the upper battery stack management unit BAU, so that the insulation detection function of the whole system is not affected even if the battery stack management unit BAU or the battery cluster management unit BCU is out of connection. The arbitration insulation detection priority and the timing round robin insulation detection mechanism are used to ensure that only one battery cluster is performing insulation detection at a certain moment, and the insulation fault battery cluster and the insulation fault details are accurately located, so that the insulation of each battery cluster does not interfere with each other, the insulation safety of the whole energy storage battery system is ensured in real time, and the reliability, stability and safety of the whole energy storage system are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The insulation detection logic flowchart of the battery cluster management unit BCU of the application;

[0018] Figure 2 The timing round robin time-sharing insulation detection flowchart of the application. DETAILED DESCRIPTION

[0019] In the following description, a large number of specific details are given to provide a more thorough understanding of the application. However, it is obvious to those skilled in the art that the application can be implemented without one or more of these details. In other examples, some technical features known in the art are not described in order not to obscure the application.

[0020] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0021] The application will be further described in connection with the following examples, which are intended to be illustrative only and should not be construed as limiting the application.

[0022] The energy storage battery system of the application is schematically shown in the figure, each battery cluster is provided with a battery management system BMS and a high-voltage box, the battery management system BMS includes at least one battery stack management unit BAU, the battery stack management unit BAU coordinates management and control of at least two battery cluster management units BCU, and the battery cluster management unit BCU coordinates management and control of at least one battery module unit BMU.

[0023] In the embodiment 1, the energy storage system includes three battery cluster parallel-connected energy storage battery systems, each battery cluster includes a set of battery management system BMS (including one battery stack management unit BAU and three battery cluster management units BCU), a high-voltage box (including a high-voltage circuit and an insulation detection module), and a battery module composed of a battery cell module and a battery module management BMU. The communication between the battery stack control unit BAU and the three battery cluster control units BCU is carried out through CAN communication, and the CAN communication protocol adopts a standard frame protocol or an extended frame protocol.

[0024] The battery cluster management unit BCU of the embodiment controls the battery module control unit BMU and the insulation detection module under the battery cluster, coordinates the high-voltage circuit to operate the high-voltage switching operation and the cluster insulation detection function.

[0025] When the battery management system BMS of the three battery clusters is started, the self-insulation detection logic in the battery cluster control unit BCU is executed, and the three battery clusters enter the insulation detection logic, and the system operation method includes the following steps:

[0026] S101: Before the high voltage is applied to the cluster, the battery cluster management units BCU of the battery clusters of the cluster 1, the cluster 2 and the cluster 3 all start the insulation detection function of the insulation detection module in the high-voltage box.

[0027] S102: Before the high voltage is applied to the cluster, the insulation detection modules of the cluster 1, the cluster 2 and the cluster 3 respectively detect the insulation resistance value, whether it reaches the insulation fault threshold value, if there is an insulation fault, the corresponding battery cluster management unit BCU prohibits the high-voltage switching of the insulation fault cluster, and at the same time, records the insulation fault position and the resistance value of the insulation resistance, the fault threshold value information to the battery cluster management units BCU of the cluster 1, the cluster 2 and the cluster 3, and synchronously reports to the battery stack control unit BAU through the communication link.

[0028] S103: Before the high voltage on the cluster, the insulation detection of cluster 1, cluster 2 and cluster 3 is normal, waiting for the high voltage closing instruction forwarded by the battery stack control unit BAU, if not received, the cluster is in the waiting power-on state, if received, the battery cluster closes the cluster insulation detection function.

[0029] S104: If the battery cluster control unit BCU receives the state of the cluster on the communication link, if only one cluster, start insulation function, if three clusters are normal and communication is normal, enter the masterless insulation detection arbitration mechanism, the method is mainly that the cluster broadcasts the arbitration synchronization insulation state data packet to the communication bus through the communication link, and other clusters perform insulation detection arbitration according to the arbitration mechanism process. The battery cluster broadcasts the arbitration synchronization insulation state data packet to each other, and each battery cluster performs restart priority according to the agreed arbitration mechanism priority (the smaller the battery cluster ID, the higher the priority). The cluster with the highest priority performs insulation detection arbitration once, ensuring that only one cluster in the three clusters opens the insulation detection function, and the other clusters close the insulation detection.

[0030] When the battery management systems of the three battery clusters are in arbitration or timing round robin insulation detection, one of the clusters receives the battery stack control unit BAU forwarding the high voltage of a cluster, and the three battery clusters enter the system battery cluster high voltage opening exit process strategy. The system operation method includes the following steps:

[0031] S105: The three battery clusters with normal insulation are in arbitration or timing round robin insulation detection.

[0032] S106: The three battery clusters with normal insulation are waiting to receive the low voltage opening instruction sent by the upper battery stack control unit BAU. If the battery cluster does not receive the low voltage opening instruction, it continues to wait, and if the battery cluster receives the low voltage opening instruction, it needs to judge whether the current low voltage battery cluster is in the insulation detection state.

[0033] S107: During the low voltage process of the cluster, the low voltage cluster is in the insulation detection state, and the low voltage cluster releases the insulation detection right of the system, and the low voltage cluster itself opens the insulation detection. The other battery clusters of the energy storage battery system perform insulation detection switching logic according to the arbitration mechanism.

[0034] S108: During the low voltage process of the cluster, the low voltage cluster is not in the insulation detection state, and the low voltage cluster itself opens the insulation detection, and the other battery clusters of the energy storage battery system run according to the previous timing round robin insulation detection switching logic.

[0035] When the communication of the battery management systems of the three battery clusters is normal and has been normally operated with high voltage, the system is in the masterless timing round robin insulation detection process as shown in Figure 2 The system operation method includes the following steps:

[0036] S201: determining whether the communication of the first cluster of battery clusters is normal, if the communication is normal, jumping to step S202, if the communication is abnormal, jumping to step S204;

[0037] S202: determining whether the first cluster is in a high voltage closing state, if the battery cluster is in a high voltage closing state, jumping to step S203, if the battery cluster is in a high voltage opening state, jumping to step S204;

[0038] S203: starting the first cluster to perform insulation detection function, after a delay of 1 minute, closing the insulation detection function of the first cluster, and jumping to step S204;

[0039] S204: determining whether the communication of the second cluster of battery clusters is normal, if the communication is normal, jumping to step S205, if the communication is abnormal, jumping to step S207;

[0040] S205: determining whether the second cluster is in a high voltage closing state, if the battery cluster is in a high voltage closing state, jumping to step S206, if the battery cluster is in a high voltage opening state, jumping to step S207;

[0041] S206: starting the second cluster to perform insulation detection function, after a delay of 1 minute, closing the insulation detection function of the second cluster, and jumping to step S207;

[0042] S207: determining whether the communication of the third cluster of battery clusters is normal, if the communication is normal, jumping to step S208, if the communication is abnormal, jumping to step S207, after the determination of the whole system of the third cluster of battery clusters is completed, jumping to step S201;

[0043] The whole system performs the timing cycle detection logic of the three clusters of battery clusters according to the above process.

[0044] In addition, it should be noted that various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

Claims

1. An insulation testing method for an energy storage system, characterized in that, The energy storage system includes: at least two battery clusters connected in parallel, each battery cluster having an independent number and a priority order, the priority order being the same as the order of the battery clusters; each battery cluster is composed of series and parallel connected cell modules, each battery cluster is equipped with a battery management system (BMS) and a high-voltage box, the BMS includes at least one battery stack management unit (BAU), the BAU coordinates and manages at least two battery cluster management units (BCUs), and the BCU coordinates and manages at least one battery module unit (BMU); each battery cluster also includes an insulation detection module, and each individual battery cluster is connected to and bound to the insulation detection module. The detection method includes the following steps: I. All battery cluster management units (BCUs) enable insulation detection functions before high-voltage closing, so that insulation detection of each cluster is enabled synchronously. Each cluster determines whether it has an insulation fault. If there is an insulation fault, it reports the cluster insulation fault to the battery stack control unit (BAU) through the battery cluster management unit (BCU). At the same time, the battery cluster control unit (BCU) prohibits high-voltage closing of that cluster. II. After determining that the battery cluster insulation fault is detected, the battery cluster management unit (BCU) reports the insulation fault information to the battery stack control unit (BAU) to accurately locate the battery cluster insulation fault location. After confirming that the battery cluster has no insulation fault, the battery cluster with normal insulation detection waits to receive the high-voltage closing command issued by the battery stack management unit (BAU) to perform the high-voltage closing action. If the battery cluster with normal insulation receives the high-voltage closing command from the battery stack management unit (BAU), it enters the system battery cluster high-voltage closing insulation detection. If the battery cluster with normal insulation does not receive the high-voltage closing command from the battery stack management unit (BAU), it is in the waiting state for the high-voltage closing command. III. After a battery cluster with normal insulation is connected to high voltage, the battery cluster management unit (BCU) receives a high-voltage tripping command from the battery stack management unit (BAU) and initiates the high-voltage tripping action. The receiving battery cluster control unit (BCU) determines whether it is currently performing insulation testing. If the receiving battery cluster management unit (BCU) is performing insulation testing, it informs other battery clusters before performing the high-voltage tripping action. Other battery clusters that are not powered down then compete for insulation testing priority through an arbitration mechanism. This insulation testing switching process implements time-sharing insulation testing. If the receiving battery cluster control unit (BCU) is not performing insulation testing, other battery clusters that are not powered down will perform time-sharing insulation testing in a timed, rotating manner. When the battery management systems of the three battery clusters are conducting arbitration or periodic round-robin insulation testing, if one of the clusters receives a forwarded message from the battery stack control unit (BAU) indicating that a high-voltage trip has been initiated for that cluster, all three battery clusters will enter the system's high-voltage trip exit process strategy. The system operation method includes the following steps: S105: Three battery clusters with normal insulation are undergoing time-sharing insulation testing through arbitration or timed rotation. S106: Three battery clusters with normal insulation are waiting to receive a high-voltage trip command from the upper-level battery stack control unit (BAU) to perform cluster-level high-voltage tripping. If a battery cluster does not receive a high-voltage trip command, it continues to wait. If a high-voltage trip command is issued, it is necessary to determine whether the current high-voltage battery cluster is in an insulation detection state. S107: During the process of the cluster being charged with high voltage, if the cluster being charged with high voltage is in the insulation detection state, the cluster being charged with high voltage will release the insulation detection right of the system, and the cluster being charged with high voltage will start its own insulation detection. Other battery clusters in the energy storage battery system that have not been charged with high voltage will use the arbitration mechanism logic to switch the insulation detection process. S108: During the high-voltage process of a cluster, if the cluster being charged is not in the insulation detection state, the cluster being charged will activate its own insulation detection, and the other non-charged battery clusters in the energy storage battery system will operate according to the previous timed rotation insulation detection switching logic.

2. The insulation testing method for an energy storage system according to claim 1, characterized in that, The switching process for time-sharing insulation detection described in step III is as follows: When all battery clusters in the energy storage system are in normal high-voltage operation, if a battery cluster experiences a system cluster communication disconnection or a cluster closing / opening action, an arbitration mechanism is required. The system then restarts the insulation detection activation action for each battery cluster according to priority from high to low, and then performs normal cycle insulation detection. The arbitration order is based on the insulation detection priority allocation according to the battery cluster ID from small to large. The smaller the battery cluster ID, the higher the priority. The insulation detection function of each battery cluster is activated one by one according to the priority order.

3. The insulation testing method for an energy storage system according to claim 1, characterized in that, The switching process for timed rotation insulation detection described in step III is as follows: When all battery clusters in the energy storage system are in the normal high-voltage closed operation process, if there is no battery cluster system cluster communication disconnection or battery cluster closing / opening action, then timed rotation insulation detection is entered. Timed rotation insulation detection is started according to the battery cluster ID from smallest to largest and is turned off after insulation detection.

4. The insulation testing method for an energy storage system according to claim 3, characterized in that, The time interval is 1 minute. If a battery cluster insulation fault or battery cluster communication interruption occurs within the insulation detection interval, the cluster will exit the timed rotation time-sharing insulation detection. Other high-voltage battery clusters with normal insulation will arbitrate once before switching back to timed rotation time-sharing insulation detection. Insulation detection will be started at a time interval of 1 minute and turned off after the insulation detection.

5. The insulation testing method for an energy storage system according to claim 1, characterized in that, The battery management system (BMS), battery stack management unit (BAU), and battery cluster management unit (BCU) are connected by the same link, forming a clustered communication system.

6. The insulation testing method for an energy storage system according to claim 1, characterized in that, The battery clusters communicate with each other through a matching and clustering communication protocol established on a communication link. Each battery cluster can send its own battery cluster insulation-related information messages to the battery stack management unit (BAU) through the communication link, and can also broadcast its insulation-related information to other battery cluster management units (BCUs) in the system through the communication link, so as to realize information exchange between the various battery cluster management units (BCUs) in the entire system.

7. The insulation testing method for an energy storage system according to claim 6, characterized in that, The communication methods include RS485, CAN, CAN-FD, and Ethernet communication.

8. The insulation testing method for an energy storage system according to claim 1, characterized in that, The high-voltage box includes a high-voltage electrical circuit, an insulation detection module, and a relay programmable switch execution unit.

9. The insulation testing method for an energy storage system according to claim 8, characterized in that, The relay programmable switch execution unit has DC high voltage closing and opening control functions; the battery cluster management unit (BCU) is matched and bound one-to-one with the high voltage electrical circuit and the insulation detection module, and the battery cluster management unit (BCU) can control the insulation detection module to turn the insulation detection function on or off.

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