Battery cluster grid fault detection method and multi-battery cluster parallel energy storage system

Abstract

The application provides a battery cluster grid-connected fault detection method and a multi-battery cluster parallel energy storage system. The detection method comprises the following steps: selecting an arbitrary battery cluster as a reference cluster, starting grid connection of the reference cluster; detecting an external load voltage of each battery cluster, and judging whether a grid connection fault exists according to the external load voltage. The grid connection fault detection method has high efficiency and a safe detection process.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a method for detecting grid-connected faults in battery clusters and an energy storage system with multiple battery clusters connected in parallel. Background Technology

[0002] Energy storage systems typically consist of multiple battery clusters connected in parallel. The DC-side output of each battery cluster is connected in parallel to a DC distribution cabinet for charging and discharging. During actual installation, due to negligence by installers, there may be instances where the DC-side output of individual battery clusters is not connected in parallel to the DC distribution cabinet, or where the positive and negative terminals are reversed, resulting in grid connection failures.

[0003] When the DC output of individual battery clusters is not connected in parallel to the DC distribution cabinet, if the energy storage system is started for charging and discharging, the actual charging and discharging power and energy of the energy storage system will be less than the design value because not all battery clusters are connected in parallel, affecting the normal operation of the energy storage system. When the positive and negative terminals of individual battery clusters are reversed, it will cause a short circuit between the batteries in the clusters, and the large current caused by the short circuit will damage the components.

[0004] To address this issue, the current method involves using a multimeter to perform short-circuit tests on each battery cluster after the energy storage system is installed. The presence of grid connection faults is detected by measuring whether the resistance between each battery cluster and the distribution cabinet is zero. However, this testing process is inefficient, and manually measuring the high-voltage circuit poses safety hazards. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for detecting grid-connected faults in battery clusters and an energy storage system for multiple battery clusters connected in parallel, so as to improve the detection efficiency of grid-connected faults in battery clusters.

[0006] To achieve the above objectives, the present invention provides a method for detecting grid connection faults in battery clusters, applicable to an energy storage system in which multiple battery clusters are connected in parallel. The detection method includes: selecting any one battery cluster as a reference cluster and starting grid connection for the reference cluster; detecting the external load voltage of each battery cluster and determining whether a grid connection fault exists based on the external load voltage.

[0007] Preferably, if the external load voltage of all battery clusters is greater than 0, it is considered that all battery clusters are connected to the grid normally; if the external load voltage of any battery cluster is 0, it is considered that the energy storage system has a grid connection fault.

[0008] Preferably, if the external load voltage of the reference cluster is equal to its total battery voltage, and the external load voltage of other battery clusters is equal to 0, the reference cluster is considered to have a grid connection fault; if the external load voltage of the Nth battery cluster is equal to 0, and the external load voltage of other battery clusters is greater than 0, the Nth battery cluster is considered to have a grid connection fault, and the Nth battery cluster is not equal to the reference cluster.

[0009] Preferably, the step of starting grid connection for the reference cluster is as follows: closing the sampling switch corresponding to the reference cluster and connecting the line between the reference cluster and the distribution cabinet; the sampling switch includes a positive switch and a negative switch, one end of the positive switch is connected to the positive power supply bus of the distribution cabinet through a first wiring harness, and one end of the negative switch is connected to the negative power supply bus of the distribution cabinet through a second wiring harness.

[0010] Preferably, the step of detecting the external load voltage of each battery cluster includes: detecting the voltage between the first wiring harness and the second wiring harness corresponding to each battery cluster to obtain the external load voltage.

[0011] Preferably, the other end of the positive switch is connected to the positive terminal of the battery cell, and the other end of the negative switch is connected to the negative terminal of the battery cell; the intermediate node between the positive terminal of the battery cell and the positive switch is set as detection point A, the intermediate node between the positive switch and the first wire harness is set as detection point B, and the intermediate node between the negative terminal of the battery cell and the negative switch is set as detection point C. The voltage between detection point A and detection point C is collected to obtain the total battery voltage of the corresponding battery cluster, and the voltage between detection point B and detection point C is collected to obtain the external load voltage of the corresponding battery cluster.

[0012] The present invention also provides an energy storage system with multiple battery clusters connected in parallel, including multiple battery clusters, each of which is connected to the grid via a sampling switch, and applies the battery cluster grid connection fault detection method as described in any of the above claims.

[0013] Preferably, each battery cluster includes a battery cell and a high-voltage box. The high-voltage box includes the sampling switch, which includes a positive switch and a negative switch. One end of the positive switch is connected to the positive power supply bus of the distribution cabinet through a first wiring harness, and the other end is connected to the positive terminal of the battery cell. One end of the negative switch is connected to the negative power supply bus of the distribution cabinet through a second wiring harness, and the other end is connected to the negative terminal of the battery cell.

[0014] Preferably, the high-voltage box includes a first sampling line and a second sampling line. The first end of the first sampling line is connected to the intermediate node of the positive terminal of the battery cell and the positive switch. The second end of the first sampling line is connected to the intermediate node of the positive switch and the first wiring harness. The first end of the second sampling line is connected to the intermediate node of the negative terminal of the battery cell and the negative switch. The second end of the second sampling line is connected to the intermediate node of the negative switch and the second wiring harness. The first sampling line and the second sampling line are connected through the intermediate node of the negative terminal of the battery cell and the negative switch.

[0015] Compared with existing technologies, the technical solution of this invention has the following advantages: By starting and connecting one battery cluster to the grid, and then detecting the external load voltage of all battery clusters, the presence of a grid connection fault in each battery cluster can be determined based on the external load voltage. This eliminates the need to start and connect all battery clusters individually, resulting in high detection efficiency and a safe detection process. Connecting the second sampling line of the high-voltage box to the second wiring harness increases the detection pathway for the external load voltage. This invention can detect not only the fault of a battery cluster not being connected to the distribution cabinet, but also the reverse polarity connection of the battery cluster and the distribution cabinet. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an energy storage system with multiple battery clusters connected in parallel, provided in an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the sampling circuit of the high-voltage box provided in an embodiment of the present invention;

[0018] Figure 3 This is a flowchart illustrating the steps of the battery cluster grid connection fault detection method provided in this embodiment of the invention. Detailed Implementation

[0019] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the present invention.

[0020] To provide the public with a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the invention, but those skilled in the art can fully understand the invention without these details.

[0021] The invention is described in more detail below by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0022] Please refer to Figure 1This invention relates to a multi-battery cluster parallel energy storage system. Applying the battery cluster grid-connection fault detection method provided by this invention, the energy storage system includes multiple battery clusters, each connected in parallel to the power supply bus of a distribution cabinet. Each battery cluster includes a battery unit and a high-voltage box. The battery unit consists of multiple battery boxes connected in series. The high-voltage box includes a sampling switch; one end of the sampling switch is connected to the power supply bus, and the other end is connected to the battery unit. When the sampling switch is closed, the DC side of the battery cluster is connected to the distribution cabinet. Specifically, each sampling switch includes a positive switch Relay+ and a negative switch Relay-. The power supply bus includes a positive power supply bus L0+ and a negative power supply bus L0-. One end of the positive switch Relay+ is connected to the positive power supply bus L0+ through a first wiring harness P+, and the other end is connected to the positive terminal BAT+ of the battery unit. One end of the negative switch Relay- is connected to the negative power supply bus L0- through a second wiring harness P-, and the other end is connected to the negative terminal BAT- of the battery unit. Figure 1 As shown, all battery clusters are connected to the power supply bus via their respective first harness P+ and second harness P-. The voltage between the first harness P+ and the second harness P- is the external load voltage V that the battery cluster supplies to the external load. load The voltage of a battery cell is the total voltage V of the battery cluster. bat When the sampling switch of one of the battery clusters is closed, under normal connection conditions, the line between the battery cluster and the distribution cabinet is connected, the power supply bus is energized, and then the first wire harness P+ and the second wire harness P- of all battery clusters are also energized.

[0023] Please refer to Figure 2 This is a schematic diagram of the sampling circuit of the high-voltage box provided in an embodiment of the present invention. Figure 2 As shown, the energy storage system with multiple battery clusters connected in parallel provided in this embodiment of the invention uses a high-voltage box including a first sampling line L1 and a second sampling line L2. The first end of the first sampling line L1 is connected to the intermediate node between the positive terminal BAT+ of the battery cell and the positive switch Relay+, and the second end of the first sampling line L1 is connected to the intermediate node between the positive switch Relay+ and the first wiring harness P+. The first end of the second sampling line L2 is connected to the intermediate node between the negative terminal BAT- of the battery cell and the negative switch Relay-, and the second end of the second sampling line L2 is connected to the intermediate node between the negative switch Relay- and the second wiring harness P-. The first sampling line L1 and the second sampling line L2 are connected through the intermediate node between the negative terminal BAT- of the battery cell and the negative switch Relay-. In this embodiment, in addition to detecting the voltage between the first wiring harness P+ and the second wiring harness P- to obtain the external load voltage V... load The external load voltage V can also be obtained by detecting the sampling line of the high-voltage box. loadHowever, in existing energy storage systems, the high-voltage box sampling line is not connected to the second wiring harness P-. Therefore, the external load voltage can only be detected through the sampling line when the negative switch Relay- is closed and conducting. In contrast, the multi-cell parallel energy storage system provided in this invention connects the second sampling line L2 to the second wiring harness P-. Even when the negative switch Relay- is open, a loop can be formed through the second sampling line L2, thereby detecting the external load voltage V through the sampling line. load This increases the detection method for external load voltage.

[0024] Please refer to Figure 3 This is a flowchart illustrating the steps of a battery cluster grid-connected fault detection method provided in an embodiment of the present invention. The detection method includes:

[0025] S10: Select any battery cluster as a reference cluster and start grid connection for the reference cluster;

[0026] S20: Detect the external load voltage of each battery cluster, and determine whether there is a grid connection fault based on the external load voltage.

[0027] In this embodiment, taking the first battery cluster as a reference cluster as an example, when grid connection is not initiated, the external load voltage V of all battery clusters is... load When the voltage equals 0 and testing is required, the sampling switches Relay+ and Relay- of the first battery cluster can be closed to start the first battery cluster into grid connection, and the external load voltage V of all battery clusters can be detected. load At this point, there are three possible scenarios:

[0028] Scenario 1: External load voltage V of all battery clusters load A value greater than 0 indicates that all battery clusters are connected to the grid normally;

[0029] Scenario 2: External load voltage V of the first battery cluster load Equal to its total battery voltage V bat External load voltage V of other battery clusters load If the value is 0, it means that there is a grid connection failure in the first battery cluster;

[0030] Scenario 3: External load voltage V of the Nth battery cluster load The external load voltage V of other battery clusters is equal to 0. load If the value is greater than 0, it means that there is a grid connection fault in the Nth battery cluster, and N is not equal to 1.

[0031] With the first battery cluster normally connected in parallel to the distribution cabinet, after it is started and connected to the grid, the power supply bus is energized, and the voltage of the power supply bus is equal to the total voltage V of the first battery cluster. batThen, the voltage between the first wire bundle P+ and the second wire bundle P- of each battery cluster is detected to obtain the external load voltage V of each battery cluster. load Based on the above situation, it is determined whether there is a grid connection fault, thereby ascertaining whether each battery cluster is properly connected in parallel to the distribution cabinet. If the first battery cluster is not connected in parallel to the distribution cabinet, the external load voltage V of the first battery cluster is... load Equal to its total battery voltage V bat However, the power supply bus is not energized, and the voltage between the first harness P+ and the second harness P- of the other battery clusters is 0, meaning the external load voltage V of all other battery clusters is zero. load It equals 0.

[0032] Specifically, the intermediate node between the positive terminal BAT+ of the battery cell and the positive switch Relay+ can be designated as detection point A, the intermediate node between the positive switch Relay+ and the first wiring harness P+ can be designated as detection point B, and the intermediate node between the negative terminal BAT- of the battery cell and the negative switch Relay- can be designated as detection point C. By collecting the voltage between detection points A and C, the total battery voltage V of the corresponding battery cluster can be obtained. bat When the negative switch Relay is open, the voltage between detection points B and C can be collected through the loop formed by the second sampling line L2 to obtain the external load voltage V of the corresponding battery cluster. load Then, based on the above situation, determine the grid connection fault. Additionally, after the reference cluster is normally connected to the grid, and the power supply bus is powered on, if some battery clusters have reversed polarity, the voltage between the first harness P+ and the second harness P- corresponding to that battery cluster will be detected as 0. At this time, the testing personnel will further detect the voltage between nodes B and C to obtain the external load voltage V of that battery cluster. load Then, based on the above three scenarios, it can be determined whether the battery cluster has a grid connection fault, and the situation of the battery cluster's circuit being reversed can be obtained.

[0033] Therefore, only one battery cluster needs to be started and connected to the grid, and then the external load voltage V of all battery clusters needs to be detected. load This invention can detect which battery cluster has a grid connection fault without requiring individual short-circuit testing of each cluster, resulting in high detection efficiency and avoiding safety hazards associated with high-voltage circuits. Furthermore, the invention can detect external load voltage through two methods, allowing for flexible testing based on project requirements. Additionally, the invention can detect whether each battery cluster is connected to the distribution cabinet, and also detect whether the wiring between each battery cluster and the distribution cabinet has reversed polarity.

[0034] Although the embodiments are described and illustrated separately above, some common technologies are involved. Those skilled in the art can replace and integrate them between the embodiments. If there is any content not explicitly described in one embodiment, then another embodiment that is described can be referred to.

[0035] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A method for detecting grid-connected faults in battery clusters, applied to an energy storage system with multiple battery clusters connected in parallel, the detection method comprising: Select any battery cluster as a reference cluster, and start grid connection of the reference cluster; The external load voltage of each battery cluster is detected, and the presence of a grid connection fault is determined based on the external load voltage. If the external load voltage of all battery clusters is greater than 0, it is considered that all battery clusters are connected to the grid normally. If the external load voltage of any battery cluster is 0, the energy storage system is considered to have a grid connection fault. If the external load voltage of the reference cluster is equal to its total battery voltage, and the external load voltage of other battery clusters is equal to 0, the reference cluster is considered to have a grid connection fault. If the external load voltage of the Nth battery cluster is 0, and the external load voltage of other battery clusters is greater than 0, the Nth battery cluster is considered to have a grid connection failure. The Nth battery cluster is not equal to the reference cluster. The steps for starting grid connection of the reference cluster are as follows: close the sampling switch corresponding to the reference cluster and connect the line between the reference cluster and the power distribution cabinet; The sampling switch includes a positive switch and a negative switch. One end of the positive switch is connected to the positive power supply bus of the distribution cabinet through a first wiring harness, and one end of the negative switch is connected to the negative power supply bus of the distribution cabinet through a second wiring harness. The step of detecting the external load voltage of each battery cluster includes: detecting the voltage between the first wiring harness and the second wiring harness corresponding to each battery cluster to obtain the external load voltage; The other end of the positive switch is connected to the positive terminal of the battery cell, and the other end of the negative switch is connected to the negative terminal of the battery cell. The intermediate node between the positive terminal of the battery cell and the positive switch is set as detection point A, the intermediate node between the positive switch and the first wire harness is set as detection point B, and the intermediate node between the negative terminal of the battery cell and the negative switch is set as detection point C. The voltage between detection point A and detection point C is collected to obtain the total battery voltage of the corresponding battery cluster, and the voltage between detection point B and detection point C is collected to obtain the external load voltage of the corresponding battery cluster.

2. An energy storage system with multiple battery clusters connected in parallel, comprising multiple battery clusters, each of which is connected to a power distribution cabinet via a sampling switch, characterized in that, The battery cluster grid connection fault detection method as described in claim 1 is applied.

3. The energy storage system with multiple battery clusters connected in parallel according to claim 2, characterized in that, Each of the battery clusters includes a battery cell and a high-voltage box. The high-voltage box includes the sampling switch, which includes a positive switch and a negative switch. One end of the positive switch is connected to the positive power supply bus of the distribution cabinet through a first wiring harness, and the other end is connected to the positive terminal of the battery cell. One end of the negative switch is connected to the negative power supply bus of the distribution cabinet through a second wiring harness, and the other end is connected to the negative terminal of the battery cell.

4. The energy storage system with multiple battery clusters connected in parallel according to claim 3, characterized in that, The high-voltage box includes a first sampling line and a second sampling line. The first end of the first sampling line is connected to the positive terminal of the battery cell and the intermediate node of the positive switch. The second end of the first sampling line is connected to the intermediate node of the positive switch and the first wiring harness. The first end of the second sampling line is connected to the negative terminal of the battery cell and the intermediate node of the negative switch. The second end of the second sampling line is connected to the intermediate node of the negative switch and the second wiring harness. The first sampling line and the second sampling line are connected through the intermediate node of the negative terminal of the battery cell and the negative switch.

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