Method and system for detecting insulation resistance in energy storage system

Abstract

The invention provides a method and system for detecting insulation resistance in an energy storage system, and the method comprises the steps: determining a battery cluster for carrying out the detection of the insulation resistance according to the current clock source time; the cluster-level control device corresponding to the battery cluster obtains the voltage of a positive pole bridge arm acquisition point and the voltage of a negative pole bridge arm acquisition point by controlling the on-off states of a plurality of switches in the insulation resistance detection circuit and calculates the resistance values of a corresponding positive pole insulation resistor and a corresponding negative pole insulation resistor, so that full-time insulation resistance detection can be realized; and through combination of a hardware circuit and a detection method, the detection precision and reliability of the insulation resistance are improved, the coupling problem of insulation detection between energy storage systems can be decoupled, real-time insulation detection of the whole energy storage system is realized, a basic guarantee is provided for safe operation of the energy storage system, and the economic benefit is improved. The method has important application value and economic value in the fields of new energy power generation, energy storage integration and the like.

Description

Technical Field

[0001] The present invention relates to the field of energy storage battery safety, and in particular to a method and system for detecting insulation resistance in an energy storage system. Background Art

[0002] With the widespread application of renewable energy and energy storage systems, the safety and reliability of energy storage systems have become particularly important. The battery cluster in the energy storage system is usually composed of multiple battery cells connected in series and parallel. Good insulation is required between multiple battery cells and between the battery cluster and the external environment. The degradation of insulation performance may cause leakage or short circuit of the battery cluster, which in turn causes safety accidents of the energy storage system. The insulation of the battery cluster is usually guaranteed by insulation resistance. The insulation resistance is the resistance set between the battery cluster and the ground. The larger the resistance value, the better the insulation performance, and the smaller the resistance value, the worse the insulation performance.

[0003] Energy storage systems, especially lithium-ion battery energy storage systems, may cause safety problems such as electric shock and fire due to insulation failure during operation. Therefore, insulation resistance detection is one of the key technologies for timely detection of insulation failures. At present, insulation resistance detection usually adopts offline detection method, which requires insulation resistance measurement when the energy storage system is shut down. There are limitations such as inability to detect in real time, long detection cycle, and limited accuracy, which makes it difficult to meet the requirements for timely detection of insulation failures in energy storage systems.

[0004] Therefore, a solution is needed that can detect insulation faults in time during the operation of the energy storage system. Summary of the invention

[0005] One object of the present application is to provide a method and system for detecting insulation resistance in an energy storage system, so as to solve the problem that it is difficult to detect insulation faults of multiple battery clusters in the energy storage system in real time under the prior art.

[0006] To achieve the above objectives, some embodiments of the present application provide a method for detecting insulation resistance in an energy storage system, the method comprising:

[0007] The system control device obtains the current clock source time, and determines the battery cluster for insulation resistance detection according to the current clock source time;

[0008] The system control device sends an insulation resistance detection start instruction to a cluster-level control device corresponding to the battery cluster that performs insulation resistance detection;

[0009] When the insulation resistance detection start instruction is received and the battery cluster for insulation resistance detection is connected to the DC bus, the cluster-level control device obtains the voltage of the positive bridge arm collection point and the voltage of the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit;

[0010] The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the voltage of the positive electrode bridge arm collection point and the voltage of the negative electrode bridge arm collection point;

[0011] The cluster-level control device returns the resistance calculation result to the system control device.

[0012] Further, the system control device determines the battery cluster for insulation resistance detection according to the current clock source time, including:

[0013] The system control device determines the battery cluster identification according to the current clock source time and a preset battery cluster identification calculation formula;

[0014] The battery cluster corresponding to the battery cluster identifier is determined as the battery cluster to be subjected to insulation resistance detection.

[0015] Furthermore, the battery cluster identification calculation formula is expressed as follows:

[0016] in, id is the battery cluster identifier, mod For the modulo operation, floor To perform floor operation, N is the number of battery clusters in the energy storage system, t is the current clock source time, T This is the insulation resistance detection time allocated to each battery cluster.

[0017] Furthermore, the method further comprises:

[0018] When the battery cluster is cut off from the DC bus, the corresponding cluster-level control device obtains the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the insulation resistance detection circuit, and calculates the resistance values ​​of the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster based on the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point.

[0019] Furthermore, the cluster-level control device obtains the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit, including:

[0020] The cluster-level control device controls the first switch, the second switch and the third switch in the corresponding insulation resistance detection circuit to be closed, and obtains the voltage of the first positive bridge arm collection point and the voltage of the first negative bridge arm collection point. The insulation resistance detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor and a first switch, a second switch, and a third switch. The first resistor, the second resistor, the third resistor and the fourth resistor are connected in series in sequence. The first resistor is connected to the positive electrode of the battery cluster, and the fourth resistor is connected to the negative electrode of the battery cluster. The first switch is set between the first resistor and the second resistor, the second switch is set between the third resistor and the fourth resistor, and the third switch is set between the connection point between the second resistor and the third resistor and the ground line.

[0021] The cluster-level control device controls the first switch and the third switch in the corresponding insulation resistance detection circuit to close and the second switch to open, so as to obtain the voltage at the second positive bridge arm collection point;

[0022] The cluster-level control device controls the first switch in the corresponding insulation resistance detection circuit to be disconnected, and the second switch and the third switch to be closed, so as to obtain the voltage at the second negative bridge arm collection point.

[0023] Furthermore, the cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including:

[0024] When the voltage at the second positive bridge arm collection point and the voltage at the second negative bridge arm collection point are both 0, the cluster-level control device determines the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster undergoing insulation resistance detection to be +∞.

[0025] Furthermore, the cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including:

[0026] When the voltage at the second positive bridge arm acquisition point is 0 and the voltage at the second negative bridge arm acquisition point is not 0, the cluster-level control device calculates the resistance value of the positive electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to a preset first calculation formula, and determines the resistance value of the negative electrode insulation resistance to be +∞. The first calculation formula is expressed as follows:

[0027]

[0028] in, R p is the positive electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor,V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V n The voltage at the collecting point of the second negative bridge arm.

[0029] Furthermore, the cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including:

[0030] When the voltage at the second positive bridge arm acquisition point is not 0 and the voltage at the second negative bridge arm acquisition point is 0, the cluster-level control device calculates the resistance value of the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to a preset second calculation formula, and determines the resistance value of the positive electrode insulation resistance to be +∞. The second calculation formula is expressed as follows:

[0031]

[0032] in, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the collecting point of the second positive bridge arm.

[0033] Furthermore, the cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including:

[0034] When the voltage at the second positive bridge arm collection point and the voltage at the second negative bridge arm collection point are both not 0, the cluster-level control device determines the battery cluster voltage according to a preset battery cluster voltage calculation formula, and then calculates the positive electrode insulation resistance value corresponding to the battery cluster undergoing insulation resistance detection according to a preset third calculation formula, and calculates the negative electrode insulation resistance value corresponding to the battery cluster undergoing insulation resistance detection according to a preset fourth calculation formula. The battery cluster voltage calculation formula is expressed as follows:

[0035]

[0036] The third calculation formula is as follows:

[0037]

[0038] The fourth calculation formula is expressed as follows:

[0039]

[0040] in, R p is the positive electrode insulation resistance, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 0 is the battery cluster voltage, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the second positive bridge arm collection point is V n The voltage at the collecting point of the second negative bridge arm.

[0041] Some embodiments of the present application also provide a system for detecting insulation resistance in an energy storage system, the system comprising:

[0042] A system control device, used to obtain the current clock source time and determine the battery cluster to be tested for insulation resistance according to the clock source time, and send an insulation test start instruction to the cluster-level control device corresponding to the battery cluster to be tested for insulation resistance;

[0043] A plurality of cluster-level control devices, corresponding to the plurality of battery clusters one by one, and connected in communication with the system control device, are used to obtain the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point of the corresponding battery cluster by controlling the opening and closing states of the plurality of switches in the corresponding insulation resistance detection circuit after receiving an insulation resistance detection start instruction, and calculate the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster for insulation resistance detection according to the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point, and then return the resistance value calculation result to the system control device;

[0044] a plurality of insulation resistance detection circuits corresponding to the plurality of battery clusters one by one, including a first resistor, a second resistor, a third resistor, a fourth resistor and a first switch, a second switch, a third switch, the first resistor, the second resistor, the third resistor and the fourth resistor being connected in series in sequence, the first resistor being connected to the positive electrode of the corresponding battery cluster, the fourth resistor being connected to the negative electrode of the corresponding battery cluster, the first switch being arranged between the first resistor and the second resistor, the second switch being arranged between the third resistor and the fourth resistor, and the third switch being arranged between a connection point between the second resistor and the third resistor and a ground line, and being used for closing or opening the first switch, the second switch and the third switch according to a control instruction of a cluster-level control device;

[0045] A plurality of pairs of DC contact switch devices correspond one to one with a plurality of battery clusters. Each pair of DC contact switch devices is respectively arranged between the positive electrode of the corresponding battery cluster and the positive electrode of the DC bus and between the negative electrode of the corresponding battery cluster and the negative electrode of the DC bus, and is used to control the corresponding battery cluster to be incorporated into or cut out of the DC bus.

[0046] Compared with the prior art, the solution provided by the present application obtains the clock source time through the system control device and determines the battery cluster for insulation resistance detection according to the clock source time, and sends an insulation detection start instruction to the cluster-level control device corresponding to the battery cluster. When the cluster-level control device receives the instruction and the battery cluster is connected to the DC bus, it obtains the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage by controlling the opening and closing states of multiple switches in the insulation resistance detection circuit, and then calculates the positive insulation resistance and negative insulation resistance corresponding to the battery cluster according to the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage. , thereby solving the conflict problem of insulation resistance detection hardware of multiple clusters in parallel through simple and reliable hardware circuits, and solving the conflict problem of insulation resistance detection timing of multiple clusters in parallel through time-sharing control methods, which can realize full-time insulation resistance detection, and through the combination of hardware circuits and detection methods, improve the detection accuracy and reliability of insulation resistance, can decouple the coupling problem of insulation detection between energy storage systems, realize real-time insulation detection of the entire energy storage system, and provide basic guarantee for the safe operation of energy storage systems. It has important application value and economic value in the fields of new energy power generation, energy storage integration, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0048] Figure 1 A flowchart of a method for detecting insulation resistance in an energy storage system is provided for some embodiments of the present application.

[0049] Figure 2A flow chart of allocating insulation resistance detection to battery clusters by a system control device provided in some embodiments of the present application.

[0050] Figure 3 A schematic diagram of the composition structure of an insulation resistance detection circuit provided in some embodiments of the present application.

[0051] Figure 4 A flow chart of a cluster-level control device controlling an insulation resistance detection circuit to perform insulation resistance detection provided in some embodiments of the present application.

[0052] Figure 5 A schematic diagram of the composition structure of an insulation resistance detection system in an energy storage system provided in some embodiments of the present application. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0054] Here, the method for detecting insulation resistance in an energy storage system according to an embodiment of the present application is suitable for use in a scenario where insulation resistance faults of multiple battery clusters are detected during operation of the energy storage system.

[0055] In this scenario, the unbalanced bridge method is usually used to detect the insulation resistance of the energy storage system. The unbalanced bridge method calculates the insulation resistance by measuring the unbalanced voltage of the bridge. How to design the unbalanced bridge has a great impact on the insulation resistance calculation method and detection accuracy. Since the energy storage system includes multiple parallel battery clusters, each battery cluster corresponds to an unbalanced bridge circuit for insulation detection. Therefore, when the energy storage system is operating normally, multiple battery clusters are not allowed to detect the corresponding insulation resistance at the same time, otherwise it will cause detection conflicts. In addition, the insulation resistance detection is usually performed when the battery cluster is not connected to the DC bus of the energy storage system, that is, in the shutdown state, and the insulation resistance detection is stopped when the battery cluster is connected to the DC bus of the energy storage system, that is, in the charging and discharging state.

[0056] The existing solutions for detecting the insulation resistance of energy storage systems have the following problems:

[0057] (1) Unreasonable hardware design. The design of the unbalanced bridge circuit in the prior art only considers the insulation resistance detection of a single battery cluster, and does not design the insulation resistance detection circuit from the perspective of the entire energy storage system containing multiple parallel battery clusters. As a result, the energy storage system with multiple battery clusters in parallel has coupling conflicts in calculating the insulation resistance during charging and discharging operation, causing problems such as complex control methods, poor calculation accuracy and long measurement time. If the calculation result is wrong, it will also cause the energy storage system to malfunction;

[0058] (2) The real-time performance of insulation resistance detection is poor. In the prior art, there is a conflict in the insulation resistance detection of energy storage systems with multiple battery clusters in parallel. Insulation resistance detection can only be performed during power-on detection or shutdown. Insulation resistance detection cannot be performed during charging and discharging. It is difficult to reflect the working status of the insulation resistance of the energy storage system in real time. In addition, regular shutdown detection is required, which affects the continuous operation of the energy storage system.

[0059] (3) Poor insulation resistance detection accuracy. The detection accuracy of non-real-time insulation resistance detection methods is greatly affected by environmental factors and it is difficult to accurately reflect the actual working status of the insulation resistance;

[0060] (4) The insulation resistance detection scheme is not perfect. The insulation resistance detection method in current technology does not consider the detection conflict problem when multiple energy storage systems are connected in parallel.

[0061] The method for detecting insulation resistance in an energy storage system provided in an embodiment of the present application can obtain the current clock source time through a system control device and determine the battery cluster for insulation resistance detection according to the clock source time, and send an insulation detection start instruction to a cluster-level control device corresponding to the battery cluster. When the cluster-level control device receives the instruction and the battery cluster is connected to the DC bus, it controls the opening and closing states of multiple switches in the insulation resistance detection circuit to obtain the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage, and then calculates the positive and negative insulation resistances corresponding to the battery cluster according to the positive and negative bridge arm acquisition point voltages. The resistance value of the insulation resistor is determined by a simple and reliable hardware circuit, thereby solving the conflict problem of the insulation resistance detection hardware of multiple clusters in parallel, and solving the conflict problem of the insulation resistance detection timing of multiple clusters in parallel through a time-sharing control method, which can realize full-time insulation resistance detection, and through the combination of hardware circuit and detection method, the detection accuracy and reliability of insulation resistance are improved, and the coupling problem of insulation detection between energy storage systems can be decoupled, and real-time insulation detection of the entire energy storage system can be realized, which provides a basic guarantee for the safe operation of the energy storage system and has important application value and economic value in the fields of new energy power generation, energy storage integration, etc.

[0062] Some embodiments of the present application provide a process of a method for detecting insulation resistance in an energy storage system, such as Figure 1 As shown, the method may include the following steps:

[0063] Step S101 : the system control device obtains the current clock source time, and determines the battery cluster to be tested for insulation resistance according to the clock source time.

[0064] Here, the energy storage system includes multiple parallel battery clusters, each battery cluster has a corresponding cluster-level control device and an insulation resistance detection circuit, and the system control device is arranged in the energy storage system and is communicatively connected with the multiple cluster-level control devices, for example, via a communication bus.

[0065] The system control device obtains the current clock source time from the preset clock source. The clock source is used to provide a square wave clock pulse signal with stable frequency and level matching for the ring pulse generator. It is usually composed of a positive feedback oscillation circuit composed of a quartz crystal oscillator and a NAND gate, and its output is sent to the ring pulse generator.

[0066] In some embodiments, the system control device obtains accurate current clock source time from the clock source by means of time synchronization, which may include but is not limited to: NTP time synchronization, B code time synchronization or protocol time synchronization.

[0067] In addition, the communication bus between the system control device and the cluster-level control device may include but is not limited to: CAN, RS485 or Ethernet, etc.

[0068] In some embodiments, the system control device determines the battery cluster identification according to the acquired current clock source time and a preset battery cluster identification calculation formula, and determines the battery cluster corresponding to the battery cluster identification as the battery cluster for insulation resistance detection.

[0069] Here, the calculation formula of the battery cluster identification can be expressed as follows:

[0070]

[0071] in, id is the battery cluster identifier, mod For the modulo operation, floor To perform floor operation, N is the number of battery clusters in the energy storage system, t is the current clock source time, T This is the insulation resistance detection time allocated to each battery cluster.

[0072] Time-sharing insulation resistance detection is performed between multiple battery clusters based on time slices, and the time of the entire insulation resistance detection cycle is evenly distributed to multiple battery clusters. The cluster-level control device that obtains the allocated insulation resistance detection time slice performs insulation resistance detection, and the cluster-level control device that does not obtain the allocated insulation resistance detection time slice stops insulation resistance detection.

[0073] Step S102 : the system control device sends an insulation resistance detection start instruction to a cluster-level control device corresponding to the battery cluster that performs insulation resistance detection.

[0074] After determining the battery cluster to be tested for insulation resistance, the system control device sends an insulation resistance test start instruction to the cluster-level control device corresponding to the battery cluster, so that the cluster-level control device can start the insulation resistance test according to the received insulation resistance test start instruction.

[0075] Here, the system control device may start or stop the insulation resistance detection of the cluster-level control device by issuing an insulation resistance detection start instruction or an insulation resistance detection stop instruction.

[0076] Figure 2 The following is a flow chart showing the process of the system control device allocating insulation resistance detection to the battery cluster in some embodiments of the present application. Figure 2 As shown, the system control device first performs clock source synchronization, obtains the timestamp (i.e., the current clock source time), and then calculates the battery cluster number that needs to be tested for insulation resistance. id , to the number id The battery cluster with the number not id The battery cluster sends an insulation resistance detection stop command.

[0077] Step S103, when the insulation resistance detection start instruction is received and the battery cluster undergoing insulation resistance detection is connected to the DC bus, the cluster-level control device obtains the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit.

[0078] Here, the cluster-level control device checks whether the battery cluster is incorporated into the DC bus of the energy storage system. When the battery cluster has been incorporated into the DC bus of the energy storage system, that is, the battery cluster is in a charging or discharging state, and the cluster-level control device receives an insulation resistance detection start instruction, the cluster-level control device performs insulation resistance detection in the order determined by the system control device.

[0079] In some embodiments, the insulation resistance detection circuit includes four resistors and three switches, the four resistors are respectively a first resistor, a second resistor, a third resistor and a fourth resistor, and the three switches are respectively a first switch, a second switch and a third switch. The first resistor, the second resistor, the third resistor and the fourth resistor are connected in series in sequence, the first resistor is connected to the positive electrode of the battery cluster, and the fourth resistor is connected to the negative electrode of the battery cluster. The first switch is arranged between the first resistor and the second resistor, the second switch is arranged between the third resistor and the fourth resistor, and the third switch is arranged between the connection point between the second resistor and the third resistor and the ground line. The cluster-level control device can control the closed or open state of the first switch, the second switch and the third switch respectively through control instructions.

[0080] Figure 3 The composition structure of the insulation resistance detection circuit in some embodiments of the present application is shown as follows: Figure 3As shown, the insulation resistance detection circuit includes 4 resistors: a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, and 3 switches: a first switch K1, a second switch K2 and a third switch K3, K1 is set between R1 and R2, K2 is set between R3 and R4, and K3 is set between the connection point between R2 and R3 and the ground wire PE. Since there is no specific physical insulation resistance, the dotted line in the figure is used to represent the virtual insulation resistance and the virtual cable, describing the virtual circuit connection with the energy storage system. The positive insulation resistance Rp in the figure represents the virtual insulation resistance formed between the positive electrode B+ of the battery cluster and the ground PE, and the negative insulation resistance Rn represents the virtual insulation resistance formed between the negative electrode B- of the battery cluster and the ground PE. In addition, V+ in the figure represents the voltage at the positive bridge arm collection point, and V- represents the voltage at the negative bridge arm collection point.

[0081] In some embodiments, a plurality of pairs of DC contact switch devices are provided in the energy storage system, each battery cluster corresponds to a pair of DC contact switch devices, each pair of DC contact switch devices includes two DC contact switch devices, one DC contact switch device is provided between the positive electrode of the battery cluster and the positive electrode of the DC bus of the energy storage system, and the other DC contact switch device is provided between the negative electrode of the battery cluster and the negative electrode of the DC bus of the energy storage system. The DC contact switch device is used to make the battery cluster merge into or cut out of the DC bus of the energy storage system by closing or opening, and the battery cluster cutting out of the DC bus of the energy storage system indicates that the battery cluster is in a non-working state.

[0082] In some embodiments, the cluster-level control device determines whether the battery cluster is incorporated into the DC bus of the energy storage system by detecting the state of the pair of DC contact switch devices. When the pair of DC contact switch devices are both closed, the cluster-level control device determines that the battery cluster is incorporated into the DC bus of the energy storage system; when at least one of the pair of DC contact switch devices is in an open state, the cluster-level control device determines that the battery cluster is not incorporated into the DC bus of the energy storage system. Figure 3 As shown, a pair of DC contact switch devices corresponding to the battery cluster are S1 and S2. The DC contact switch device S1 is arranged between the positive electrode of the battery cluster and the positive electrode DC+ of the DC bus of the energy storage system. The other DC contact switch device S2 is arranged between the negative electrode of the battery cluster and the negative electrode DC- of the DC bus of the energy storage system. Both S1 and S2 are currently in the disconnected state, indicating that the battery cluster is not incorporated into the DC bus of the energy storage system.

[0083] Here, the cluster-level control device obtains the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit, which may specifically include the following steps:

[0084] 1) The cluster-level control device controls the first switch, the second switch and the third switch in the corresponding insulation resistance detection circuit to be closed, and obtains the voltage of the first positive bridge arm collection point and the voltage of the first negative bridge arm collection point;

[0085] 2) The cluster-level control device controls the first switch and the third switch in the corresponding insulation resistance detection circuit to close and the second switch to open, thereby obtaining the voltage at the collection point of the second positive bridge arm;

[0086] 3) The cluster-level control device controls the first switch in the corresponding insulation resistance detection circuit to be disconnected, and the second switch and the third switch to be closed, so as to obtain the voltage at the collection point of the second negative bridge arm.

[0087] Still Figure 3 The cluster-level control device controls the first switch K1, the second switch K2 and the third switch K3 to close, collects the voltage of the positive bridge arm and the voltage of the negative bridge arm, and obtains the voltage of the first positive bridge arm collection point V 1 and the first negative bridge arm collection point voltage V 2; The cluster-level control device controls the first switch K1 and the third switch K3 to close, and the second switch K2 to open, and collects the voltage of the positive bridge arm to obtain the voltage of the second positive bridge arm collection point V p The cluster-level control device then controls the second switch K2 and the third switch K3 to close, the first switch K1 to open, and the negative bridge arm voltage is collected to obtain the voltage at the second negative bridge arm collection point. V n .

[0088] Step S104 , the cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster to be tested for insulation resistance according to the voltage at the positive electrode bridge arm collection point and the voltage at the negative electrode bridge arm collection point.

[0089] Specifically, the cluster-level control device determines or calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster according to different values ​​of the acquired positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage.

[0090] In some embodiments, the voltage at the second positive bridge arm acquisition point is obtained. V p and the voltage at the second negative bridge arm collection point V n When both are 0, the cluster-level control device will set the positive electrode insulation resistance of the battery cluster corresponding to the insulation resistance detection R p And negative insulation resistance R n The resistance value is determined to be +∞.

[0091] In some embodiments, the voltage at the second positive bridge arm acquisition point is obtained. V p The voltage at the second negative bridge arm collection point is 0. V n When the value is not 0, the cluster-level control device calculates the positive electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the preset first calculation formula R p The negative insulation resistance R n The resistance value is determined to be +∞.

[0092] The first calculation formula can be expressed as follows:

[0093]

[0094] in, R p is the positive electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V n The voltage at the collecting point of the second negative bridge arm.

[0095] In some embodiments, the voltage at the second positive bridge arm acquisition point is obtained. V p Not 0 and the voltage at the second negative bridge arm collection point V n When the insulation resistance is 0, the cluster-level control device calculates the insulation resistance of the negative electrode corresponding to the battery cluster for insulation resistance detection according to the preset second calculation formula. R n The positive insulation resistance R p The resistance value is determined to be +∞.

[0096] The second calculation formula can be expressed as follows:

[0097]

[0098] in, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the collecting point of the second positive bridge arm.

[0099] In some embodiments, the voltage at the second positive bridge arm acquisition point is obtained. V p and the voltage at the second negative bridge arm collection point V n When both are not 0, the cluster-level control device determines the battery cluster voltage according to the preset battery cluster voltage calculation formula, and then calculates the positive electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the preset third calculation formula. R p The insulation resistance of the negative electrode corresponding to the battery cluster for insulation resistance detection is calculated according to the preset fourth calculation formula R n resistance value.

[0100] The battery cluster voltage calculation formula can be expressed as follows:

[0101]

[0102] The third calculation formula can be expressed as follows:

[0103]

[0104] The fourth calculation formula can be expressed as follows:

[0105]

[0106] In the above three formulas, R p is the positive electrode insulation resistance, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 0 is the battery cluster voltage, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the second positive bridge arm collection point is V n The voltage at the collecting point of the second negative bridge arm.

[0107] In addition, if a battery cluster in the energy storage system is not incorporated into the DC bus of the energy storage system, that is, the battery cluster is in a shutdown state, the cluster-level control device corresponding to the battery cluster can also independently perform insulation resistance detection without receiving the corresponding insulation resistance detection start instruction.

[0108] In some embodiments, when the battery cluster is cut out of the DC bus, the cluster-level control device corresponding to the battery cluster can obtain the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point by controlling the opening and closing states of multiple switches in the insulation resistance detection circuit, and calculate the resistance values ​​of the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster according to the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point. The specific voltage acquisition process and resistance determination process are the same as the corresponding contents in the aforementioned step S103 and step S104, and will not be repeated here.

[0109] Figure 4 The flowchart of the cluster-level control device controlling the insulation resistance detection circuit to perform insulation resistance detection in some embodiments of the present application is shown. Figure 4 As shown, the cluster-level control device first determines whether the DC contact switch devices S1 and S2 are both disconnected. If not, it determines whether an insulation resistance detection start instruction is received. If the insulation resistance detection start instruction is not received from the system control device, switches K1, K2 and K3 are disconnected to stop insulation resistance detection. If the cluster-level control device determines that the DC contact switch devices S1 and S2 are both disconnected, or receives an insulation resistance detection start instruction, a subsequent insulation resistance detection process is performed, firstly controlling switches K1, K2 and K3 to close and collecting V 1 and V 2. Then control switches K1 and K3 to close, K2 to open, and collect V p , then control switches K2 and K3 to close, K1 to open, and collect V n Finally, the insulation resistance is calculated based on the collected data. R p and R n .

[0110] Step S105: the cluster-level control device returns the resistance calculation result to the system control device.

[0111] After obtaining the resistance calculation results of the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster undergoing insulation resistance detection, the cluster-level control device returns the resistance calculation results to the system control device, and the system control device can determine whether there is an insulation fault at present based on the resistance calculation results.

[0112] Figure 5 A detection system for insulation resistance in an energy storage system in some embodiments of the present application is shown. Figure 5 As shown, the system includes a system control device, a plurality of cluster-level control devices, a plurality of insulation resistance detection circuits and a plurality of pairs of DC contact switch devices.

[0113] A system control device, used to obtain the current clock source time and determine the battery cluster to be tested for insulation resistance according to the clock source time, and send an insulation test start instruction to the cluster-level control device corresponding to the battery cluster to be tested for insulation resistance;

[0114] A plurality of cluster-level control devices, corresponding to the plurality of battery clusters one by one, and connected in communication with the system control device, are used to obtain the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point of the corresponding battery cluster by controlling the opening and closing states of the plurality of switches in the corresponding insulation resistance detection circuit after receiving an insulation resistance detection start instruction, and calculate the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster for insulation resistance detection according to the voltage at the positive bridge arm acquisition point and the voltage at the negative bridge arm acquisition point, and then return the resistance value calculation result to the system control device;

[0115] Multiple insulation resistance detection circuits correspond to multiple battery clusters one by one. The structure of the insulation resistance detection circuit is as follows: Figure 3 As shown, it includes a first resistor, a second resistor, a third resistor, a fourth resistor and a first switch, a second switch, and a third switch, the first resistor, the second resistor, the third resistor and the fourth resistor are connected in series in sequence, the first resistor is connected to the positive electrode of the corresponding battery cluster, the fourth resistor is connected to the negative electrode of the corresponding battery cluster, the first switch is arranged between the first resistor and the second resistor, the second switch is arranged between the third resistor and the fourth resistor, and the third switch is arranged between the connection point between the second resistor and the third resistor and the ground line, and is used to close or open the first switch, the second switch and the third switch according to the control instruction of the cluster-level control device;

[0116] A plurality of pairs of DC contact switch devices correspond one to one with a plurality of battery clusters. Each pair of DC contact switch devices is respectively arranged between the positive electrode of the corresponding battery cluster and the positive electrode of the DC bus and between the negative electrode of the corresponding battery cluster and the negative electrode of the DC bus, and is used to control the corresponding battery cluster to be incorporated into or cut out of the DC bus.

[0117] In summary, the solution provided by the present application can obtain the current clock source time through the system control device and determine the battery cluster for insulation resistance detection according to the clock source time, and send an insulation detection start instruction to the cluster-level control device corresponding to the battery cluster. When the cluster-level control device receives the instruction and the battery cluster is connected to the DC bus, it obtains the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage by controlling the opening and closing states of multiple switches in the insulation resistance detection circuit, and then calculates the positive insulation resistance and negative insulation resistance corresponding to the battery cluster according to the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage. value, thereby solving the conflict problem of insulation resistance detection hardware of multiple clusters in parallel through simple and reliable hardware circuits, and solving the conflict problem of insulation resistance detection timing of multiple clusters in parallel through time-sharing control methods, which can realize full-time insulation resistance detection, and through the combination of hardware circuits and detection methods, improve the detection accuracy and reliability of insulation resistance, can decouple the coupling problem of insulation detection between energy storage systems, realize real-time insulation detection of the entire energy storage system, and provide basic guarantee for the safe operation of energy storage systems. It has important application value and economic value in the fields of new energy power generation, energy storage integration, etc.

[0118] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

Claims

1. A method for detecting insulation resistance in an energy storage system, characterized in that: The method includes: The system control device obtains the current clock source time, and determines the battery cluster for insulation resistance detection according to the current clock source time; The system control device sends an insulation resistance detection start instruction to the cluster-level control device corresponding to the battery cluster performing insulation resistance detection; When the insulation resistance detection start instruction is received and the battery cluster for insulation resistance detection is connected to the DC bus, the cluster-level control device obtains the voltage of the positive bridge arm collection point and the voltage of the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit; The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage; The cluster-level control device returns the resistance calculation result to the system control device.

2. The method according to claim 1, characterized in that The system control device determines the battery cluster for insulation resistance detection according to the current clock source time, including: The system control device determines the battery cluster identifier according to the current clock source time and a preset battery cluster identifier calculation formula; The battery cluster corresponding to the battery cluster identifier is determined as the battery cluster to be subjected to insulation resistance detection.

3. The method according to claim 2, characterized in that The battery cluster identification calculation formula is expressed as follows: ， in, id is the battery cluster identifier, mod For the modulo operation, floor To perform floor operation, N is the number of battery clusters in the energy storage system, t is the current clock source time, T This is the insulation resistance detection time allocated to each battery cluster.

4. The method according to claim 1, characterized in that: The method further includes: In the case where the battery cluster is cut off from the DC bus, the corresponding cluster-level control device obtains the positive bridge arm collection point voltage and the negative bridge arm collection point voltage by controlling the opening and closing states of multiple switches in the insulation resistance detection circuit, and calculates the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster according to the positive bridge arm collection point voltage and the negative bridge arm collection point voltage.

5. The method according to claim 1, characterized in that The cluster-level control device obtains the voltage at the positive bridge arm collection point and the voltage at the negative bridge arm collection point by controlling the opening and closing states of multiple switches in the corresponding insulation resistance detection circuit, including: The cluster-level control device controls the first switch, the second switch and the third switch in the corresponding insulation resistance detection circuit to be closed, and obtains the voltage of the first positive bridge arm collection point and the voltage of the first negative bridge arm collection point, wherein the insulation resistance detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor and a first switch, a second switch, a third switch, the first resistor, the second resistor, the third resistor and the fourth resistor are connected in series in sequence, the first resistor is connected to the positive electrode of the battery cluster, the fourth resistor is connected to the negative electrode of the battery cluster, the first switch is set between the first resistor and the second resistor, the second switch is set between the third resistor and the fourth resistor, and the third switch is set between the connection point between the second resistor and the third resistor and the ground line; The cluster-level control device controls the first switch and the third switch in the corresponding insulation resistance detection circuit to be closed and the second switch to be opened, so as to obtain the voltage at the second positive bridge arm collection point; The cluster-level control device controls the first switch in the corresponding insulation resistance detection circuit to be disconnected, and the second switch and the third switch to be closed, so as to obtain the voltage at the second negative bridge arm collection point.

6. The method according to claim 5, characterized in that The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including: When the voltage at the second positive bridge arm collection point and the voltage at the second negative bridge arm collection point are both 0, the cluster-level control device determines the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster undergoing insulation resistance detection to be +∞.

7. The method according to claim 5, characterized in that The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including: When the voltage at the second positive bridge arm acquisition point is 0 and the voltage at the second negative bridge arm acquisition point is not 0, the cluster-level control device calculates the resistance value of the positive electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to a preset first calculation formula, and determines the resistance value of the negative electrode insulation resistance to be +∞, wherein the first calculation formula is expressed as follows: ， in, R p is the positive electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V n The voltage at the collecting point of the second negative bridge arm.

8. The method according to claim 5, characterized in that The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including: When the voltage at the second positive bridge arm acquisition point is not 0 and the voltage at the second negative bridge arm acquisition point is 0, the cluster-level control device calculates the resistance value of the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to a preset second calculation formula, and determines the resistance value of the positive electrode insulation resistance to be +∞, wherein the second calculation formula is expressed as follows: ， in, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the collecting point of the second positive bridge arm.

9. The method according to claim 5, characterized in that The cluster-level control device calculates the positive electrode insulation resistance and the negative electrode insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive electrode bridge arm collection point voltage and the negative electrode bridge arm collection point voltage, including: In the case where the voltage at the second positive bridge arm collection point and the voltage at the second negative bridge arm collection point are both not 0, the cluster-level control device determines the battery cluster voltage according to a preset battery cluster voltage calculation formula, and then calculates the positive electrode insulation resistance corresponding to the battery cluster undergoing insulation resistance detection according to a preset third calculation formula, and calculates the negative electrode insulation resistance corresponding to the battery cluster undergoing insulation resistance detection according to a preset fourth calculation formula, wherein the battery cluster voltage calculation formula is expressed as follows: ， The third calculation formula is expressed as follows: ， The fourth calculation formula is expressed as follows: ， in, R p is the positive electrode insulation resistance, R n is the negative electrode insulation resistance, R 1. R 2. R 3. R 4 are respectively the first resistor, the second resistor, the third resistor and the fourth resistor, V 0 is the battery cluster voltage, V 1 is the voltage at the first positive bridge arm collection point, V 2 is the voltage at the first negative bridge arm collection point, V p The voltage at the collection point of the second positive bridge arm is V n The voltage at the collecting point of the second negative bridge arm.

10. A detection system for insulation resistance in an energy storage system, characterized in that: The system includes: A system control device, used to obtain a current clock source time and determine a battery cluster for performing insulation resistance detection according to the clock source time, and send an insulation detection start instruction to a cluster-level control device corresponding to the battery cluster for performing insulation resistance detection; A plurality of cluster-level control devices, corresponding to a plurality of battery clusters one by one, and connected in communication with the system control device, are used to obtain the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage of the corresponding battery cluster by controlling the opening and closing states of a plurality of switches in the corresponding insulation resistance detection circuit after receiving the insulation resistance detection start instruction, and calculate the positive insulation resistance and the negative insulation resistance corresponding to the battery cluster for insulation resistance detection according to the positive bridge arm acquisition point voltage and the negative bridge arm acquisition point voltage, and then return the resistance value calculation result to the system control device; a plurality of insulation resistance detection circuits, corresponding to a plurality of battery clusters one by one, including a first resistor, a second resistor, a third resistor, a fourth resistor and a first switch, a second switch, a third switch, the first resistor, the second resistor, the third resistor and the fourth resistor are sequentially connected in series, the first resistor is connected to the positive electrode of the corresponding battery cluster, the fourth resistor is connected to the negative electrode of the corresponding battery cluster, the first switch is arranged between the first resistor and the second resistor, the second switch is arranged between the third resistor and the fourth resistor, and the third switch is arranged between a connection point between the second resistor and the third resistor and a ground line, and is used to close or open the first switch, the second switch and the third switch according to a control instruction of the cluster-level control device; A plurality of pairs of DC contact switch devices correspond one to one with a plurality of battery clusters. Each pair of DC contact switch devices is respectively arranged between the positive electrode of the corresponding battery cluster and the positive electrode of the DC bus and between the negative electrode of the corresponding battery cluster and the negative electrode of the DC bus, and is used to control the corresponding battery cluster to be incorporated into or cut out of the DC bus.

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