Energy storage system and branch abnormality detection method thereof

Abstract

The present application provides an energy storage system and a branch anomaly detection method thereof. In the branch anomaly detection method of the energy storage system, since the branch current and branch voltage of each branch are combined when determining the abnormal branch, the accuracy of determining the abnormal branch is improved. Therefore, this method can be used to realize abnormal detection of each branch in the energy storage inverter, that is, the branch anomaly detection method of the energy storage system can realize abnormal detection of each branch in the energy storage inverter; in addition, since the branch anomaly detection method of the energy storage system can realize abnormal detection of each branch in the energy storage inverter only through software, there is no need to add additional hardware and supporting hardware circuits to the energy storage inverter. Therefore, the branch anomaly detection method of the energy storage system provided by the present application can reduce the branch anomaly detection cost of the energy storage inverter.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to an energy storage system and a branch abnormality detection method thereof. Background Art

[0002] At present, high-power energy storage inverters in energy storage systems mostly adopt a multi-branch DC side structure design. Specifically, the DC side of the energy storage inverter includes at least two pairs of connection ports, each pair of connection ports is connected to the DC bus through a branch, and the DC bus is connected to the DC side of the DCAC conversion module in the energy storage inverter. A branch fuse is set on each branch.

[0003] Typically, microswitch feedback is configured in each branch so that the corresponding branch with a branch fuse abnormality can be detected in a timely manner. However, if microswitch feedback is configured in each branch, the branch abnormality detection cost of the energy storage inverter will increase, and at the same time, the overall cost of the energy storage inverter will increase. In addition, it will not only occupy space in the cabinet and increase the design difficulty, but also increase the number of feedback signal sampling ports in the circuit, which increases the circuit complexity.

[0004] Therefore, how to reduce the cost of branch anomaly detection of energy storage inverters is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of this, the present invention provides an energy storage system and a branch abnormality detection method thereof, so as to reduce the branch abnormality detection cost of the energy storage inverter.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] On one hand, the present application provides a method for detecting branch anomalies in an energy storage system, wherein an energy storage inverter in the energy storage system includes at least two branches, each of which is indirectly connected to a one-to-one corresponding battery cluster in the energy storage system. The method for detecting branch anomalies in the energy storage system includes:

[0008] Determining whether the operating power of the energy storage inverter is greater than or equal to a preset power;

[0009] If the operating power of the energy storage inverter is greater than or equal to the preset power, an abnormal branch is determined in each branch based on the branch current and branch voltage of each branch; the abnormal branch is the branch where the abnormality occurs;

[0010] After the abnormal branches are determined, the connection between each abnormal branch and the corresponding battery cluster is disconnected.

[0011] Optionally, determining an abnormal branch in each of the branches based on the branch current and the branch voltage includes:

[0012] Determining a suspected abnormal branch in each branch according to the branch current of each branch; the suspected abnormal branch is the branch suspected of having an abnormality;

[0013] After the suspected abnormal branches are determined, the abnormal branch is determined from the suspected abnormal branches according to the branch voltages of the branches.

[0014] Optionally, determining a suspected abnormal branch in each branch according to the branch current of each branch includes:

[0015] Determining whether the branch currents of the branches are all greater than or equal to a preset current;

[0016] If there is at least one branch whose branch current is smaller than the preset current, the branch whose branch current is smaller than the preset current is determined as the suspected abnormal branch.

[0017] Optionally, if in the energy storage system, the branches are connected to the corresponding battery clusters through one-to-one corresponding switch boxes, determining the abnormal branch from among the suspected abnormal branches according to the branch voltages of the branches includes:

[0018] After a first preset time, determining whether the absolute values ​​of the differences between the branch voltages of the suspected abnormal branches and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to the first preset difference;

[0019] If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the first preset difference, the suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the first preset difference is determined as the abnormal branch.

[0020] Optionally, if in the energy storage system, the branches are connected to the corresponding battery clusters through one-to-one corresponding DC converters, then determining the abnormal branch from among the suspected abnormal branches based on the branch voltages of the branches includes:

[0021] Controlling the DC converter corresponding to the suspected abnormal branch to stop or standby;

[0022] Determining whether the absolute values ​​of the differences between the branch voltages of the suspected abnormal branches and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to a second preset difference;

[0023] If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the second preset difference, the suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the second preset difference is determined as the abnormal branch.

[0024] Optionally, controlling the DC converter to be in standby mode includes:

[0025] Controlling a DCDC conversion module in the DC converter to stop power conversion, and closing at least one DC switch in the DC converter;

[0026] Controlling the DC converter to shut down includes:

[0027] The DCDC conversion module is controlled to stop power conversion, and at least one of the DC switches is disconnected.

[0028] Optionally, the energy storage inverter further includes: a DC-AC conversion module having a DC side connected to each of the branches via a DC bus; after determining that the operating power of the energy storage inverter is less than the preset power, further including:

[0029] determining whether the DCAC conversion module is in standby mode and / or whether each of the branches is connected to the corresponding battery cluster;

[0030] If the DCAC conversion module is in standby mode, and / or each of the branches is connected to the corresponding battery cluster, determining whether the absolute value of the difference between the branch voltage of each branch and the bus voltage of the DC bus in the energy storage inverter is less than or equal to a third preset difference;

[0031] If there is at least one branch whose branch voltage has an absolute value greater than the third preset difference value than the bus voltage, the branch whose branch voltage has an absolute value greater than the third preset difference value than the bus voltage is determined as an abnormal branch;

[0032] After the abnormal branch is determined, the connection between the abnormal branch and the corresponding battery cluster is disconnected.

[0033] Optionally, determining whether the DCAC conversion module is in standby mode includes:

[0034] Determining whether the main circuit in the DCAC conversion module stops power conversion, and whether the DC side switch and the AC side switch in the DCAC conversion module are both closed;

[0035] If the main circuit stops power conversion and the DC side switch and the AC side switch are both closed, it is determined that the DCAC conversion module is in standby mode.

[0036] Optionally, the determination of whether each branch is connected to the corresponding battery cluster is only applicable to the energy storage system in which the branches are connected to the corresponding battery clusters through a one-to-one corresponding switch box;

[0037] Determining whether each of the branches is connected to the corresponding battery cluster includes:

[0038] Determining whether the switches in the switch boxes corresponding to the branches are all closed;

[0039] If the switches in the switch boxes corresponding to the branches are all closed, it is determined that the branches are connected to the corresponding battery clusters.

[0040] Optionally, if in the energy storage system, the branches are connected to the corresponding battery clusters through a one-to-one corresponding switch box, disconnecting the abnormal branch from the corresponding battery cluster includes:

[0041] The switch in the switch box corresponding to the abnormal branch is controlled to be disconnected.

[0042] Optionally, if in the energy storage system, the branches are connected to the corresponding battery clusters through one-to-one corresponding DC converters, disconnecting the abnormal branch from the corresponding battery cluster includes:

[0043] The DC converter corresponding to the abnormal branch is controlled to shut down.

[0044] Optionally, after determining that the absolute values ​​of the differences between the branch voltages of each target branch and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to corresponding preset differences, the method further includes:

[0045] Determining whether the absolute value of the difference between the branch voltage of each target branch and the bus voltage is less than or equal to the corresponding preset difference within a second preset time; the target branch is a suspected abnormal branch or the branch;

[0046] If the absolute value of the difference between the branch voltage of each target branch and the bus voltage is less than or equal to the corresponding preset difference within the second preset time, it is determined that no abnormality occurs in each target branch;

[0047] If the absolute value of the difference between the branch voltage of each target branch and the bus voltage is not less than or equal to the corresponding preset difference within the second preset time, return to the step of determining whether the absolute value of the difference between the branch voltage of each target branch and the bus voltage of the DC bus in the energy storage inverter is less than or equal to the corresponding preset difference.

[0048] Optionally, if in the energy storage system, the branches are connected to the corresponding battery clusters via one-to-one DC converters, then after determining that no abnormality occurs in each target branch based on the voltage difference, the method further includes:

[0049] Control the startup and operation of each of the DC converters corresponding to each of the target branches.

[0050] Optionally, controlling the DC converter to start up and operate includes:

[0051] The DCDC conversion module in the DC converter performs power conversion and controls the DC switch in the DC converter to close.

[0052] On the other hand, the present application provides an energy storage system, comprising: an energy storage inverter, a controller, at least two battery clusters, and at least two switch devices; the energy storage inverter comprises: at least two branches; wherein:

[0053] One side of each branch is connected to a corresponding battery cluster via a one-to-one corresponding switch device;

[0054] The energy storage inverter and each of the switching devices are controlled by the controller, and the controller is used to execute the branch abnormality detection method of the energy storage system as described in any one of the above aspects of the present application.

[0055] Optionally, each of the switching devices is a switch box or a DC converter.

[0056] Optionally, the switch box includes: a fuse and a switch connected in series.

[0057] Optionally, the DC converter includes: a DCDC conversion module and at least one DC switch connected in series.

[0058] Optionally, the energy storage inverter further includes: a DC bus and a DCAC conversion module; wherein:

[0059] The other side of each branch is connected to the DC side of the DCAC conversion module through the DC bus;

[0060] The AC side of the DCAC conversion module is connected to the AC side of the energy storage inverter;

[0061] The DCAC conversion module is controlled by the controller.

[0062] Optionally, the DCAC conversion module includes: a main circuit, a DC side switch and an AC side switch; wherein:

[0063] The DC side of the main circuit is connected to the DC side of the DCAC conversion module through the DC side switch;

[0064] The AC side of the main circuit is connected to the AC side of the DCAC conversion module through the AC side switch;

[0065] The DC side switch and the AC side switch are both controlled by the controller.

[0066] As can be seen from the above technical solution, the present invention provides a branch anomaly detection method for an energy storage system. In the branch anomaly detection method for the energy storage system, since the branch current and branch voltage of each branch are combined when determining the abnormal branch, the accuracy of determining the abnormal branch is improved. Therefore, this method can be used to realize abnormal detection of each branch in the energy storage inverter, that is, the branch anomaly detection method for the energy storage system can realize abnormal detection of each branch in the energy storage inverter; in addition, since the branch anomaly detection method for the energy storage system can realize abnormal detection of each branch in the energy storage inverter only through software, there is no need to add additional hardware and supporting hardware circuits to the energy storage inverter. Therefore, the branch anomaly detection method for the energy storage system provided by the present application can reduce the cost of branch anomaly detection of the energy storage inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0068] Figures 1 to 3 Flowcharts showing three implementations of the branch abnormality detection method for the energy storage system provided in the embodiments of the present application;

[0069] Figures 4 to 8 Schematic diagram of the five implementation methods of step S220 provided in the embodiments of the present application;

[0070] Figure 9 A flowchart of an implementation method after determining that the operating power of the energy storage inverter is less than a preset power is provided in an embodiment of the present application;

[0071] Figure 10 A flowchart of an implementation method for determining whether a DCAC conversion module is in standby mode provided in an embodiment of the present application;

[0072] Figure 11 A flowchart of an implementation method for determining whether both the DC side switch and the AC side switch in a DCAC conversion module are closed, provided in an embodiment of the present application;

[0073] Figure 12 A flow chart of another embodiment of the present application after determining that the operating power of the energy storage inverter is less than the preset power;

[0074] Figures 13 to 16 The following are structural schematic diagrams of four implementation modes of the energy storage system provided in the embodiments of the present application. DETAILED DESCRIPTION

[0075] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0076] In this application, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0077] In order to reduce the cost of branch anomaly detection of an energy storage inverter, another embodiment of the present application provides a branch anomaly detection method for an energy storage system. In this energy storage system, the energy storage inverter includes at least two branches, and each branch is indirectly connected to a one-to-one corresponding battery cluster in the energy storage system.

[0078] In actual applications, each branch can be connected to the corresponding battery cluster through a one-to-one corresponding switch box. The energy storage system using this structure is called a single-stage mode energy storage system; each branch can also be connected to the corresponding battery cluster through a one-to-one corresponding DC converter. The energy storage system using this structure is called a two-stage mode energy storage system. No specific limitations are made here, and it can be determined according to the specific situation, and all are within the scope of protection of this application.

[0079] The specific process of the branch abnormality detection method of the energy storage system is as follows: Figure 1 As shown, the specific steps include:

[0080] S110: Determine whether the operating power of the energy storage inverter is greater than or equal to a preset power.

[0081] If the operating power of the energy storage inverter is greater than or equal to the preset power, step S120 is executed.

[0082] Among them, the preset power is equal to the product of the division value of the controller when detecting the branch operating power of each branch and the number of branches; it can be seen that when the operating power of the energy storage inverter is greater than the preset power, even if the branch operating power of the branch changes from the division value to zero, the controller can still detect it, thereby avoiding misjudgment.

[0083] For example, assume that the energy storage inverter includes two branches with a preset power of 20W. When the branch operating power of each branch is 10W, if the branch fuse on a branch fails, that is, a circuit breaker fault occurs in the branch, the branch current on the branch becomes 0, and the branch operating power of the branch is 0. Since the controller has a division value of 10W when detecting the branch operating power of each branch, the controller can detect that the branch operating power of the branch has changed.

[0084] In practical applications, the preset power can be set according to specific circumstances and is not specifically limited here, and is within the scope of protection of this application.

[0085] S120 , combining the branch currents and branch voltages of each branch, and determining an abnormal branch in each branch.

[0086] The abnormal branch is a branch where an abnormality occurs. In practical applications, each branch is provided with a branch fuse, so the abnormality of the branch specifically refers to: an abnormality occurs in the branch fuse in the branch, for example, the fuse is broken.

[0087] Since the branch current and branch voltage will change when a fault occurs in each branch, the abnormal branch can be determined by using the branch current or branch voltage of each branch. However, the accuracy is low at this time. Combining the two to determine the abnormal branch will greatly improve the accuracy of determining the abnormal branch, so this method can be used to realize abnormal detection of each branch in the energy storage inverter.

[0088] S130 , after determining the abnormal branches, disconnecting each abnormal branch from the corresponding battery cluster.

[0089] If the energy storage system is a single-stage mode energy storage system, the specific implementation method of disconnecting each abnormal branch from the corresponding battery cluster is: controlling the switch in the switch box corresponding to the abnormal branch to be disconnected.

[0090] If the energy storage system is a dual-stage mode energy storage system, the specific implementation method of disconnecting each abnormal branch from the corresponding battery cluster is: controlling the DC converter corresponding to the abnormal branch to shut down.

[0091] It should be noted that the specific implementation method of controlling the shutdown of the DC converter will be described in detail in the following embodiments and will not be repeated here.

[0092] From the above, it can be seen that by combining the branch current and branch voltage of each branch, it is possible to realize abnormality detection of each branch in the energy storage inverter, that is, the branch abnormality detection method of the energy storage system can realize abnormality detection of each branch in the energy storage inverter; in addition, since the branch abnormality detection method of the energy storage system can realize abnormality detection of each branch in the energy storage inverter only through software, there is no need to add additional hardware and supporting hardware circuits to the energy storage inverter. Therefore, the branch abnormality detection method of the energy storage system provided in this application can reduce the branch abnormality detection cost of the energy storage inverter.

[0093] Another embodiment of the present application provides a specific implementation of step S120, and the specific process is as follows: Figure 2 As shown, the specific steps include:

[0094] S210 . Determine a suspected abnormal branch in each branch according to the branch current of each branch.

[0095] Among them, the suspected abnormal branch is a branch that is suspected of having an abnormality. The suspected fault of the branch is specifically: the branch fuse in the branch is suspected of having an abnormality; the reason for being suspected of having an abnormality is that it is impossible to accurately determine whether the branch has an abnormality based solely on the branch current.

[0096] S220: After the suspected abnormal branches are determined, an abnormal branch is determined from the suspected abnormal branches according to the branch voltages of the branches.

[0097] In actual applications, in addition to the above-mentioned implementation of step S120 provided in this embodiment, another implementation is also included, specifically: first determine the suspected abnormal branch based on the branch voltage, and then determine the abnormal branch in each suspected abnormal branch based on the branch current; there is no specific limitation on the two implementations here, which can be determined according to the specific situation, and are all within the scope of protection of this application.

[0098] It should be noted that in actual applications, when an abnormality occurs in the branch fuse on the branch, the branch current of the branch will change immediately, so the abnormality of the branch can be detected in time based on the current. Therefore, in actual applications, the former implementation method of step S120 is the preferred implementation method.

[0099] Another embodiment of the present application provides a specific implementation of step S210, and the specific process is as follows: Figure 3 As shown, the specific steps include:

[0100] S211 , determining whether the branch currents of all branches are greater than or equal to a preset current.

[0101] If the branch current of at least one branch is less than the preset current, step S212 is executed; if the branch currents of all branches are greater than or equal to the preset current, the branch abnormality detection method of the energy storage system is stopped.

[0102] S212: Determine a branch whose branch current is less than a preset current as a suspected abnormal branch.

[0103] Since the branch current on the branch will decrease after the branch fuse on the branch is broken, when the branch current of the branch is less than the preset current, it is considered that the branch fuse on the branch may be broken or other abnormalities may occur.

[0104] Another embodiment of the present application provides a specific implementation of step S220. This implementation is applicable to a single-stage energy storage system. The specific process of this implementation is as follows: Figure 4 As shown, the specific steps include:

[0105] S221. After a first preset time, determine whether the absolute values ​​of the differences between the branch voltages of each suspected abnormal branch and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to a first preset difference.

[0106] If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the first preset difference, step S222 is executed.

[0107] In practical applications, no matter the energy storage system is a single-stage mode energy storage system or a dual-stage mode energy storage system, when a branch fuse on a branch circuit has an abnormality, the branch current of the branch circuit will change immediately.

[0108] In a single-stage energy storage system, when a branch fuse on a branch circuit fails, the branch circuit is still connected to the corresponding battery cluster. Therefore, in a short period of time, the branch voltage of the branch circuit can still be approximately consistent with the bus voltage. However, as time goes on, other branches will charge or discharge under the action of the energy storage inverter, so the bus voltage will change accordingly. That is, the branch voltage of the branch circuit is no longer equal to the bus voltage, and this can be used as a basis for judging whether the branch circuit has failed.

[0109] As can be seen from the above, the first preset time is used to ensure that there is a difference between the branch voltage of the abnormal branch and the branch voltage of the normal branch. Therefore, the first preset time can be set based on experience.

[0110] In addition, since there are errors in the branch voltage detected in actual applications, in order to avoid misjudgment, the judgment condition is improved from the branch voltage not being equal to the bus voltage to the difference between the branch voltage and the bus voltage being greater than the first preset difference.

[0111] Furthermore, as can be seen from the above, within the first preset time, the energy storage inverter may charge or discharge the battery cluster. Therefore, the branch voltage of the faulty branch may be lower than or higher than the branch voltage of the non-faulty branch. This improves the judgment condition from the difference between the branch voltage and the bus voltage being greater than the first preset difference to the absolute value of the difference between the branch voltage and the bus voltage being greater than the first preset difference.

[0112] S222: Determine a suspected abnormal branch, in which the absolute value of the difference between the branch voltage and the bus voltage is greater than a first preset difference, as an abnormal branch.

[0113] This embodiment also provides another specific implementation of step S220. The specific process of this implementation is as follows: Figure 5 As shown, this embodiment, based on the above embodiment, further includes the following steps after determining that the absolute value of the difference between the branch voltage and the bus voltage of each suspected abnormal branch is less than or equal to the first preset difference:

[0114] S223: Determine whether the absolute value of the difference between the branch voltage and the bus voltage of each suspected abnormal branch is less than or equal to the first preset difference within the second preset time.

[0115] If the absolute value of the difference between the branch voltage and the bus voltage of each suspected abnormal branch is less than or equal to the first preset difference within the second preset time, execute step S224; if the absolute value of the difference between the branch voltage and the bus voltage of each suspected abnormal branch is not less than or equal to the first preset difference within the second preset time, return to execute step S221.

[0116] S224: Determine that no abnormality occurs in any of the suspected abnormal branches.

[0117] Another embodiment of the present application provides another specific implementation of step S220. This implementation is applicable to a dual-stage energy storage system. The specific process of this implementation is as follows: Figure 6 As shown, the specific steps include:

[0118] S201: Control the DC converter corresponding to the suspected abnormal branch to stop or enter standby mode.

[0119] In practical applications, the DC converter includes a DCDC conversion module and at least one DC switch connected in series.

[0120] The specific implementation method of controlling the shutdown of the DC converter is: controlling the DCDC conversion module to stop power conversion, and closing at least one DC switch; in actual application, stopping power conversion and closing the DC switch can be performed simultaneously, or one after the other. There is no specific limitation here and it can be determined according to the specific situation. All of these are within the scope of protection of this application.

[0121] The specific implementation method of controlling the DC converter to be in standby mode is: controlling the DCDC conversion module to stop power conversion, and disconnecting at least one DC switch; in actual application, stopping power conversion and disconnecting the DC switch can be performed simultaneously, or one after the other. There is no specific limitation here and it can be determined according to the specific situation. All of them are within the scope of protection of this application.

[0122] S202: Determine whether the absolute values ​​of the differences between the branch voltages of each suspected abnormal branch and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to a second preset difference.

[0123] If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the second preset difference, step S203 is executed.

[0124] It should be noted that the setting of the second preset difference and the absolute value in step S202 are the same as those in step S221 and will not be repeated here.

[0125] S203: Determine a suspected abnormal branch, in which the absolute value of the difference between the branch voltage and the bus voltage is greater than a second preset difference, as an abnormal branch.

[0126] This embodiment also provides another specific implementation of step S220. The specific process of this implementation is as follows: Figure 7 As shown, based on the previous embodiment, this embodiment further includes the following steps after determining that the absolute value of the difference between the branch voltage and the bus voltage of each suspected abnormal branch is less than or equal to the second preset difference:

[0127] S204: Determine whether the absolute value of the difference between the branch voltage of each suspected abnormal branch and the bus voltage is less than or equal to a second preset difference within a second preset time.

[0128] If the absolute value of the difference between the branch voltage of each suspected abnormal branch and the bus voltage is less than or equal to the second preset difference within the second preset time, execute step S205; if the absolute value of the difference between the branch voltage of each suspected abnormal branch and the bus voltage is not less than or equal to the second preset difference within the second preset time, return to execute step S202.

[0129] It should be noted that the setting of the second preset difference and the absolute value in step S204 are the same as those in step S221 and will not be repeated here.

[0130] S205: Determine that no abnormality occurs in any of the suspected abnormal branches.

[0131] This embodiment also provides another specific implementation of step S220. The specific process of this implementation is as follows: Figure 8 As shown, based on the previous embodiment, this embodiment further includes the following steps after step S205:

[0132] S206 : Control the startup and operation of each DC converter corresponding to each suspected abnormal branch.

[0133] The specific implementation method of controlling the startup operation of the DC converter is: controlling the DCDC conversion module to perform power conversion, and closing at least one DC switch; in actual application, power conversion and DC switch closing can be performed simultaneously, or one after the other, which is not specifically limited here and can be determined according to the specific situation, all of which are within the scope of protection of this application.

[0134] Another embodiment of the present application provides another implementation of a branch abnormality detection method for an energy storage system. In the energy storage system, the energy storage inverter further includes: a DCAC conversion module whose DC side is connected to each branch through a DC bus.

[0135] This implementation is based on the above embodiment. After determining that the operating power of the energy storage inverter is less than the preset power, Figure 9 As shown, the following steps are also included:

[0136] S310 , determining whether the DCAC conversion module is in standby mode, and / or whether each branch is connected to its corresponding battery cluster.

[0137] If the DCAC conversion module is in standby mode and / or each branch is connected to its corresponding battery cluster, step S320 is executed; if the DCAC conversion module is not in standby mode and each branch is not connected to its corresponding battery cluster, the branch abnormality detection method of the energy storage system is stopped.

[0138] It should be noted that, since it has been determined before step S310 that the operating power of the energy storage inverter is less than the preset power, if it is further determined that the DCAC conversion module is not in standby mode, it indicates that the DCAC conversion module is shut down. In addition, under normal circumstances, each branch is simultaneously connected to its corresponding battery cluster, or is simultaneously disconnected from its corresponding battery, so as to fully utilize the energy storage system.

[0139] This embodiment provides a specific implementation method for determining whether the DCAC conversion module is in standby mode. The specific structure is as follows: Figure 10 As shown, the specific steps include:

[0140] S410 , determining whether the main circuit in the DCAC conversion module stops power conversion, and whether the DC side switch and the AC side switch in the DCAC conversion module are both closed.

[0141] If the main circuit in the DCAC conversion module stops power conversion and the DC side switch and the AC side switch in the DCAC conversion module are both closed, step S420 is executed; if the main circuit in the DCAC conversion module stops power conversion and the DC side switch and the AC side switch in the DCAC conversion module are both open, step S430 is executed.

[0142] S420: Determine whether the DCAC conversion module is in standby mode.

[0143] S430: Determine whether the DCAC conversion module is not in standby mode.

[0144] In addition, the determination of whether each branch is connected to its corresponding battery cluster is only applicable to a single-stage energy storage system. This embodiment provides a specific implementation method for determining whether the DC side switch and the AC side switch in the DCAC conversion module are both closed. The specific structure is as follows: Figure 11 As shown, the specific steps include:

[0145] S510: Determine whether the switches in the switch boxes corresponding to the branches are all closed.

[0146] If the switches in the switch boxes corresponding to the branches are all closed, step S520 is executed; if the switches in the switch boxes corresponding to the branches are not closed, step S530 is executed.

[0147] It should be noted that, normally, the switches in each switch box are closed or opened at the same time to maximize the utilization of the energy storage system.

[0148] S520: Determine whether each branch is connected to its corresponding battery cluster.

[0149] S530: Determine whether each branch is connected to its corresponding battery cluster.

[0150] S320: Determine whether the absolute values ​​of the differences between the branch voltages of each branch and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to a third preset difference.

[0151] If the absolute value of the difference between the branch voltage and the bus voltage of at least one branch is greater than the third preset value, step S330 is executed.

[0152] It should be noted that the setting of the third preset difference and the absolute value in step S320 are the same as those in step S221 and will not be repeated here.

[0153] S330: Determine a branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than a third preset difference as an abnormal branch.

[0154] S340: After the abnormal branch is determined, disconnect the abnormal branch from the corresponding battery cluster.

[0155] This embodiment also provides another implementation method of the branch abnormality detection method of the energy storage system. The specific process of this implementation method is as follows: Figure 12 As shown, based on the previous embodiment, after determining that the absolute value of the difference between the branch voltage of each branch and the bus voltage of the DC bus in the energy storage inverter is less than or equal to the third preset difference, the following steps are also included:

[0156] S350: Determine whether the absolute value of the difference between the branch voltage and the bus voltage of each branch is less than or equal to a third preset difference within the second preset time.

[0157] If the absolute value of the difference between the branch voltage of each branch and the bus voltage is less than or equal to the third preset difference within the second preset time, execute step S360; if the absolute value of the difference between the branch voltage of each branch and the bus voltage is not less than or equal to the third preset difference within the second preset time, return to execute step S320.

[0158] It should be noted that the setting of the third preset difference and the absolute value in step S350 are the same as those in step S221 and will not be repeated here.

[0159] S360: Determine that no abnormality occurs in any branch.

[0160] Another embodiment of the present application provides an energy storage system, the specific structure of which is as follows: Figure 13 (Only two battery clusters 20 and two switch devices 30 are shown as an example) as shown, specifically including: energy storage inverter 10, controller (in order to simplify the diagram, Figure 13 The controller is not shown), at least two battery clusters 20 and at least two switch devices 30; the energy storage inverter 10 includes: at least two branches 11; the connection relationship between the various devices is as follows:

[0161] One side of each branch 11 is connected to a corresponding battery cluster 20 through a one-to-one corresponding switch device 30; the energy storage inverter 10 and each switch device 30 are controlled by a controller, which is used to execute the branch abnormality detection method of the energy storage system provided in the above embodiment.

[0162] In practical applications, such as Figure 13 As shown, the energy storage inverter 10 also includes: a DC bus 12 and a DCAC conversion module 13; the other side of each branch 11 is connected to the DC side of the DCAC conversion module 13 through the DC bus 12; the AC side of the DCAC conversion module 13 is connected to the AC side of the energy storage inverter 10; and the DCAC conversion module 13 is controlled by a controller.

[0163] The specific structure of the DCAC conversion module 13 is as follows: Figure 14 As shown, it specifically includes: a main circuit 131, a DC side switch 132 and an AC side switch 133; the DC side of the main circuit 131 is connected to the DC side of the DCAC conversion module 13 through the DC side switch 132; the AC side of the main circuit 131 is connected to the AC side of the DCAC conversion module 13 through the AC side switch 133; the DC side switch 132 and the AC side switch 133 are both controlled by a controller.

[0164] Optionally, the switch device 30 may be a switch box 31, such as Figure 15 As shown, the energy storage system is a single-stage mode energy storage system, wherein the switch box 31 includes a fuse FU and a switch S connected in series; the switch device 30 can also be a DC converter 32, such as Figure 16 As shown, the energy storage system is a two-stage mode energy storage system, wherein the DC converter 32 includes a DCDC conversion module 321 and at least one DC switch Sd connected in series. This is not specifically limited here and may be determined according to the specific circumstances, all within the scope of protection of this application.

[0165] For the above description of the disclosed embodiments, the features recorded in the various embodiments in this specification can be replaced or combined with each other, so that professionals in this field can implement or use this application. The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above with a preferred embodiment, it is not used to limit the present invention. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for detecting branch abnormalities in an energy storage system, characterized in that: The energy storage inverter in the energy storage system includes at least two branches, each of which is indirectly connected to a one-to-one corresponding battery cluster in the energy storage system. The branch abnormality detection method of the energy storage system includes: Determining whether the operating power of the energy storage inverter is greater than or equal to a preset power; If the operating power of the energy storage inverter is greater than or equal to the preset power, an abnormal branch is determined in each branch based on the branch current and branch voltage of each branch; the abnormal branch is the branch where the abnormality occurs; After determining the abnormal branches, disconnecting each abnormal branch from the corresponding battery cluster; The step of determining an abnormal branch in each of the branches by combining the branch current and the branch voltage of each of the branches includes: Determining a suspected abnormal branch in each branch according to the branch current of each branch; the suspected abnormal branch is the branch suspected of having an abnormality; After the suspected abnormal branches are determined, determining the abnormal branch among the suspected abnormal branches according to the branch voltages of the branches; or, Determining an abnormal branch in each of the branches based on the branch current and the branch voltage of each of the branches includes: determining a suspected abnormal branch in each branch according to the branch voltage of each branch; After the suspected abnormal branches are determined, the abnormal branch is determined from the suspected abnormal branches according to the branch currents of the branches.

2. The method for detecting branch abnormalities of an energy storage system according to claim 1, wherein: Determining a suspected abnormal branch in each branch according to the branch current of each branch includes: Determining whether the branch currents of the branches are all greater than or equal to a preset current; If there is at least one branch whose branch current is smaller than the preset current, the branch whose branch current is smaller than the preset current is determined as the suspected abnormal branch.

3. The method for detecting branch abnormalities of an energy storage system according to claim 1, wherein: If, in the energy storage system, the branches are connected to the corresponding battery clusters through corresponding switch boxes, determining the abnormal branch from among the suspected abnormal branches according to the branch voltages of the branches includes: After a first preset time, determining whether the absolute values ​​of the differences between the branch voltages of the suspected abnormal branches and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to the first preset difference; If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the first preset difference, the suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the first preset difference is determined as the abnormal branch.

4. The method for detecting branch abnormalities of an energy storage system according to claim 1, wherein: If, in the energy storage system, the branches are connected to the corresponding battery clusters via one-to-one corresponding DC converters, determining the abnormal branch from among the suspected abnormal branches based on the branch voltages of the branches includes: Controlling the DC converter corresponding to the suspected abnormal branch to stop or standby; Determining whether the absolute values ​​of the differences between the branch voltages of the suspected abnormal branches and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to a second preset difference; If there is at least one suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the second preset difference, the suspected abnormal branch whose absolute value of the difference between the branch voltage and the bus voltage is greater than the second preset difference is determined as the abnormal branch.

5. The method for detecting branch abnormalities of an energy storage system according to claim 4, wherein: Controlling the DC converter to be in standby mode comprises: Controlling a DCDC conversion module in the DC converter to stop power conversion, and closing at least one DC switch in the DC converter; Controlling the DC converter to shut down includes: The DCDC conversion module is controlled to stop power conversion, and at least one of the DC switches is disconnected.

6. The method for detecting branch abnormalities of an energy storage system according to claim 1, wherein: The energy storage inverter further includes: a DC-AC conversion module whose DC side is connected to each branch via a DC bus; after determining that the operating power of the energy storage inverter is less than the preset power, further including: determining whether the DCAC conversion module is in standby mode and / or whether each of the branches is connected to the corresponding battery cluster; If the DCAC conversion module is in standby mode, and / or each of the branches is connected to the corresponding battery cluster, determining whether the absolute value of the difference between the branch voltage of each branch and the bus voltage of the DC bus in the energy storage inverter is less than or equal to a third preset difference; If there is at least one branch whose branch voltage has an absolute value greater than the third preset difference value than the bus voltage, the branch whose branch voltage has an absolute value greater than the third preset difference value than the bus voltage is determined as an abnormal branch; After the abnormal branch is determined, the connection between the abnormal branch and the corresponding battery cluster is disconnected.

7. The method for detecting branch abnormalities of an energy storage system according to claim 6, characterized in that: Determining whether the DCAC conversion module is in standby mode includes: Determining whether the main circuit in the DCAC conversion module stops power conversion, and whether the DC side switch and the AC side switch in the DCAC conversion module are both closed; If the main circuit stops power conversion and the DC side switch and the AC side switch are both closed, it is determined that the DCAC conversion module is in standby mode.

8. The method for detecting branch abnormalities of an energy storage system according to claim 6, wherein: The judgment on whether each branch is connected to the corresponding battery cluster is only applicable to the energy storage system in which the branches are connected to the corresponding battery clusters through a one-to-one corresponding switch box; Determining whether each of the branches is connected to the corresponding battery cluster includes: Determining whether the switches in the switch boxes corresponding to the branches are all closed; If the switches in the switch boxes corresponding to the branches are all closed, it is determined that the branches are connected to the corresponding battery clusters.

9. The method for detecting branch abnormalities of an energy storage system according to any one of claims 1 to 8, characterized in that: If, in the energy storage system, the branches are connected to the corresponding battery clusters through corresponding switch boxes, disconnecting the abnormal branches from the corresponding battery clusters includes: The switch in the switch box corresponding to the abnormal branch is controlled to be disconnected.

10. The method for detecting branch abnormalities in an energy storage system according to any one of claims 1 to 8, characterized in that: If, in the energy storage system, the branches are connected to the corresponding battery clusters through one-to-one corresponding DC converters, disconnecting the abnormal branches from the corresponding battery clusters includes: The DC converter corresponding to the abnormal branch is controlled to shut down.

11. The method for detecting branch abnormalities of an energy storage system according to any one of claims 1 to 8, characterized in that: After determining that the absolute values ​​of the differences between the branch voltages of the target branches and the bus voltage of the DC bus in the energy storage inverter are all less than or equal to the corresponding preset differences, the method further includes: Determining whether the absolute value of the difference between the branch voltage of each target branch and the bus voltage is less than or equal to the corresponding preset difference within a second preset time; the target branch is a suspected abnormal branch or the branch; If the absolute value of the difference between the branch voltage of each target branch and the bus voltage is less than or equal to the corresponding preset difference within the second preset time, it is determined that no abnormality occurs in each target branch; If the absolute value of the difference between the branch voltage of each target branch and the bus voltage is not less than or equal to the corresponding preset difference within the second preset time, return to the step of determining whether the absolute value of the difference between the branch voltage of each target branch and the bus voltage of the DC bus in the energy storage inverter is less than or equal to the corresponding preset difference.

12. The method for detecting branch abnormalities of an energy storage system according to claim 11, characterized in that: If, in the energy storage system, the branches are connected to the corresponding battery clusters via one-to-one DC converters, then after determining that no abnormality occurs in each target branch based on the voltage difference, the method further includes: Control the startup and operation of each of the DC converters corresponding to each of the target branches.

13. The method for detecting branch abnormalities of an energy storage system according to claim 12, wherein: Controlling the DC converter to start up and operate includes: The DCDC conversion module in the DC converter performs power conversion and controls the DC switch in the DC converter to close.

14. An energy storage system, characterized in that: include: An energy storage inverter, a controller, at least two battery clusters, and at least two switch devices; The energy storage inverter includes at least two branches; wherein: One side of each branch is connected to a corresponding battery cluster via a one-to-one corresponding switch device; The energy storage inverter and each of the switching devices are controlled by the controller, and the controller is used to execute the branch abnormality detection method of the energy storage system according to any one of claims 1 to 13.

15. The energy storage system according to claim 14, characterized in that: Each of the switch devices is a switch box or a DC converter.

16. The energy storage system according to claim 15, characterized in that: The switch box includes a fuse and a switch connected in series.

17. The energy storage system according to claim 15, characterized in that: The DC converter includes: a DCDC conversion module and at least one DC switch connected in series.

18. The energy storage system according to any one of claims 14 to 17, characterized in that: The energy storage inverter further includes: a DC bus and a DCAC conversion module; wherein: The other side of each branch is connected to the DC side of the DCAC conversion module through the DC bus; The AC side of the DCAC conversion module is connected to the AC side of the energy storage inverter; The DCAC conversion module is controlled by the controller.

19. The energy storage system according to claim 18, characterized in that: The DCAC conversion module includes: a main circuit, a DC side switch and an AC side switch; wherein: The DC side of the main circuit is connected to the DC side of the DCAC conversion module through the DC side switch; The AC side of the main circuit is connected to the AC side of the DCAC conversion module through the AC side switch; The DC side switch and the AC side switch are both controlled by the controller.

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