Energy storage system

Abstract

An energy storage system 10 includes: a PCS 30; a plurality of storage battery banks 51 connected in parallel to the PCS 30 via a power line; a circuit breaker 65 provided in each of the plurality of storage battery banks 51; and a detector 53 for detecting an abnormality of the energy storage system; and control devices 40, 55, 75. When an abnormality in the energy storage system is detected, the control devices 40, 55, 75 open the circuit breaker 65 and disconnect the storage battery bank 51 from the power line after stopping the PCS 30.

Description

Energy Storage Systems

[0001] The present invention relates to energy storage systems.

[0002] In order to achieve efficient energy management, the introduction of energy storage systems is being promoted. When the demand for electricity is lower than the supply, the energy storage system charges a storage battery with surplus electricity, and when the demand for electricity exceeds the supply, the storage battery is discharged to make up for the power shortage. Patent Document 1 discloses a technology related to the energy storage system.

[0003] JP 2023-65595 A

[0004] Energy storage systems often use multiple battery banks connected in parallel. In the event of an abnormality, it is desirable to protect each battery bank by using a circuit breaker to disconnect it from the main circuit (power line). When an emergency shutdown of the energy storage system is required in the event of an abnormality, if the circuit breakers are opened to disconnect the battery banks before the PCS is shut down, current may be concentrated in some of the circuit breakers due to a discrepancy in the circuit breaker operation timing, which could cause the circuit breakers to fail or deteriorate.

[0005] An object of the present invention is to suppress breakdowns and deterioration of circuit breakers.

[0006] An energy storage system according to one embodiment of the present invention includes a PCS, a plurality of battery banks connected in parallel to the PCS via a power line, circuit breakers provided in each of the plurality of battery banks, a detector that detects an abnormality in the energy storage system, and a control device.

[0007] When the control device detects an abnormality in the energy storage system, it stops the PCS and then opens the circuit breaker to disconnect the battery bank from the power line.

[0008] This technology can reduce circuit breaker failure and deterioration.

[0009] Block diagram of the energy storage system Circuit diagram of the PCS Perspective view of the storage module Diagram showing current concentration in the circuit breaker Current interruption flow

[0010] (Outline of this embodiment) (1) An energy storage system according to one embodiment of the present invention includes a PCS, a plurality of battery banks connected in parallel to the PCS via power lines, circuit breakers provided in each of the plurality of battery banks, a detector that detects abnormalities in the energy storage system, and a control device.

[0011] When the control device detects an abnormality in the energy storage system, the control device stops the PCS and then opens the circuit breaker to disconnect the battery bank from the power line. In the energy storage system described in (1), any configuration other than the above is optional and may be any configuration.

[0012] In the energy storage system described in (1), when an abnormality occurs, the PCS is stopped first, and then the circuit breaker is opened to isolate the battery bank. If the PCS is stopped first, there is no current, so the circuit breaker can be opened with almost no current flowing, regardless of the operation timing. Therefore, there is almost no damage associated with opening, and it is possible to suppress circuit breaker failure and deterioration.

[0013] (2) The energy storage system described in (1) may include a plurality of battery panels each housing the battery bank. When the control device detects an abnormality in one of the battery panels, the control device may stop the PCS and then disconnect the battery bank in all battery panels. This configuration can prevent an abnormality occurring in one battery panel from spreading to other battery panels. This improves the safety and reliability of the energy storage system.

[0014] (3) The energy storage system described in (1) may include a plurality of battery panels that house the battery banks. When the control device detects an abnormality in one of the plurality of battery panels, the control device may stop the PCS and then disconnect the battery bank in the battery panel that detected the abnormality, while maintaining the connection of the battery banks in the other battery panels. With this configuration, after returning to normal, simply starting the PCS enables early operation of the energy storage system using the battery panels in which no abnormality was detected.

[0015] (4) In the energy storage system described in (2) or (3), the detector may be a fire detector that detects a fire in the battery panel. In this configuration, in the event of a fire, charging and discharging are stopped and the battery panel is disconnected from the main circuit, thereby preventing the battery bank or the battery panel from reaching or causing a further unsafe event. The detector may be a ground fault detector, a pressure detector, or any other detector that detects some kind of abnormality.

[0016] <First Embodiment> 1. Description of Energy Storage System 10 Fig. 1 is a block diagram of an energy storage system 10. The energy storage system 10 is a system that is connected to a power grid 1 and adjusts the supply and demand of power. The power grid 1 may be that of a power utility company, or may be an independent power grid that is based on the stand-alone operation output of a large-scale power conditioner.

[0017] The energy storage system 10 includes a PCS 30, a PCS control unit 40, and a plurality of battery panels 50A to 50C. PCS 30 is an abbreviation for Power Conditioning System.

[0018] The PCS 30 is a bidirectional power converter capable of inverse conversion (DC to AC) and forward conversion (AC to DC). Figure 2 shows an example of the circuit of the PCS 30. The PCS 30 can be configured with a noise filter 31, a switch 32, an inrush current prevention circuit 33, a link capacitor 34, an inverter 35, a current sensor 36, an LC filter 37, a switch 38, etc.

[0019] The PCS control unit 40 includes, for example, a central processing unit (CPU) and a memory for storing various data. The PCS control unit 40 controls the PCS 30 in response to commands from higher-level systems such as an energy management system (EMS) and adjusts the supply and demand of power.

[0020] Specifically, when the demand for power is lower than the supply, the battery panels 50A to 50C are charged with the surplus power, and when the demand for power exceeds the supply, the battery panels 50A to 50C are discharged to make up for the power shortage. The PCS control unit 40, the battery panel control unit (described later) 55, and the bank monitoring device (described later) 75 are examples of the "control device" of the present technology.

[0021] 2. Configuration of Battery Panels 50A to 50C The battery panel 50A is a device for storing energy, and is composed of a plurality of battery banks 51, a detector 53, a battery panel control unit 55, and a housing 57 that houses these components.

[0022] The battery bank 51 is composed of a plurality of storage modules 60 connected in series, a fuse 63, a current sensor 64, a circuit breaker 65 such as a relay or MC (magnetic contactor), a plurality of module monitoring devices 70, and a bank monitoring device 75.

[0023] 3, the power storage module 60 is a unit formed by fixing a plurality of storage battery cells 61 connected in series to a frame 62. The storage battery cells 61 can be any of a variety of cells that can store electricity (can be repeatedly charged and discharged), such as non-aqueous electrolyte secondary battery cells such as lithium ion secondary batteries, capacitors, NAS battery cells, and redox flow battery cells.

[0024] 1 , the battery bank 51 is connected to a power line (main circuit) L1 via a circuit breaker 65. The bank monitoring device 75 controls the circuit breaker 65 to connect and disconnect the battery bank 51 to and from the power line L1.

[0025] A module monitoring device 70 is provided for each power storage module 60. The module monitoring device 70 monitors the temperature of the power storage module 60 and the cell voltage of each storage battery cell 61.

[0026] The module monitoring device 70 and the bank monitoring device 75 are connected via communication line L3 and can communicate with each other. Each bank monitoring device 75 and the battery panel control unit 55 are connected to the PCS control unit 40 via communication line L4.

[0027] 1 shows a configuration in which three storage battery banks 51 are connected in parallel. The number of parallel storage battery banks 51 is an example, and does not have to be three as long as it is two or more.

[0028] The detector 53 detects abnormalities in the battery panel 50A. The detector 53 is, for example, a thermistor that detects temperature abnormalities in the battery panel 50A or a fire detector that detects fires. The battery panel control unit 55 monitors the state of the battery panel 50A based on the detection results of the detector 53. Detection of abnormalities by the detector 53 is one example, and abnormalities may also be detected by the module monitoring device 70 that detects abnormalities in the battery cells 61, or by the bank monitoring device 75 that detects abnormalities in the flowing current.

[0029] The configurations of the battery panels 50B and 50C are the same as that of the battery panel 50A. The battery panels 50B and 50C are connected to the PCS 30 via a power line L2. The three battery panels 50A to 50C are connected in parallel.

[0030] 3. Current Concentration and Circuit Breaker Failure The energy storage system 1 uses multiple battery banks 51 in parallel, and in the event of an abnormality, each battery bank 51 is disconnected from the main circuit (power lines L1, L2) using a circuit breaker 65 to protect the battery cells 60. When an abnormality occurs and the energy storage system 1 is to be brought to an emergency stop (charging / discharging), if the circuit breakers 65 are opened to disconnect the battery banks 51 before the PCS 30 is stopped, current may be concentrated in some of the circuit breakers 65 due to a discrepancy in the operation timing of the circuit breakers 65.

[0031] For example, as shown in FIG. 4, if the operation of circuit breaker 65C among circuit breakers 65A to 65C is delayed, current will be concentrated in circuit breaker 65C, and if circuit breaker 65C is opened in that state, there is a possibility that circuit breaker 65C will fail or deteriorate.

[0032] Therefore, in this embodiment, when an abnormality occurs, the PCS 30 is stopped first and then the circuit breaker 65 is opened, thereby reducing damage caused by the opening operation of the circuit breaker 65.

[0033] 5, a description will be given of the current interruption flow of the storage battery bank 51. The current interruption flow of the storage battery bank 51 is composed of six steps S10 to S60, and is executed at predetermined intervals while the energy storage system 10 is in operation.

[0034] In S10, each of the battery panels 50A to 50C is monitored for abnormalities by the detector 53. If the detector 53 detects a fire or temperature abnormality in the battery panel 50A to 50C (YES), the process proceeds to S20.

[0035] When the process proceeds to S20, the detector 53 notifies the battery panel control unit 55 of the occurrence of an abnormality in the battery panels 50A to 50C. Then, the process proceeds to S30.

[0036] When the process proceeds to S30, the battery panel control unit 55 notifies the PCS control unit 40 of the occurrence of an abnormality in the battery panels 50A to 50C. For example, if an abnormality is detected in the battery panel 50A, the battery panel control unit 55 of the battery panel 50A notifies the PCS control unit 40 of the occurrence of an abnormality in the battery panel 50A. Then, the process proceeds to S40.

[0037] When the process proceeds to S40, the PCS control unit 40 issues a command to the PCS 30 to stop the operation of the PCS 30. As a result, the PCS 30 stops charging and discharging, and all the storage battery panels 50A to 50C become currentless. Then, the process proceeds to S50.

[0038] When the process proceeds to S50, the PCS control unit 40 notifies the bank monitoring devices 75 of all battery banks 51 connected to the power lines L1 and L2 (i.e., all battery banks 51 on all battery panels 50A to 50C) of an emergency stop. Then, the process proceeds to S60.

[0039] When the process proceeds to S60, the bank monitoring device 75 of each battery panel 50A-50C sends a command to the circuit breaker 65 to open the circuit breaker 65. This simultaneously disconnects the battery banks 51 from the power lines L1 and L2 in all battery panels 50A-50C. As a result, the energy storage system 10 comes to an emergency stop.

[0040] 4. Effects In this configuration, when an abnormality occurs, the PCS 30 is stopped first, and then the circuit breaker 65 is opened to isolate the battery bank 51. If the PCS 30 is stopped first, there is no current, so the circuit breaker 65 can be opened with almost no current flowing, regardless of operation timing. Therefore, there is almost no damage associated with opening, and failure or deterioration of the circuit breaker 65 can be suppressed.

[0041] <Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0042] (1) In the above embodiment, an abnormality in the battery panels 50A to 50C is detected and the energy storage system 10 is brought to an emergency stop. However, for example, an abnormality in the PCS 30 may be detected and the energy storage system 10 may be brought to an emergency stop.

[0043] (2) In the above embodiment, if an abnormality is detected in the battery panel 50A, the battery banks 51 are simultaneously disconnected in all of the battery panels 50A to 50C after the PCS is stopped. However, this is not limited to this. After the PCS is stopped, the battery bank 51 may be disconnected only in the battery panel 50A where the abnormality is detected, and the battery banks 51 may remain connected in the other battery panels 50B and 50C.

[0044] (3) In the above embodiment, an energy storage system including multiple battery panels 50A to 50C has been described as an example. In the present technology, as long as two or more battery banks 51 are connected to the PCS 30, the number of battery panels 50 may be one or more. Furthermore, the energy storage system may not include a panel (housing 57). Furthermore, the energy storage system may include one battery bank 51 for each of the multiple battery panels 50 connected to the PCS 30.

[0045] (4) In the above embodiment, when an abnormality is detected, the PCS 30 is stopped and then the circuit breaker 65 is opened by cooperation between the PCS control unit 50, the storage battery control unit 55, and the bank monitoring device 75. The PCS control unit 50, the storage battery control unit 55, and the bank monitoring device 75 may be integrated into two units (for example, an integrated two-unit configuration of the bank monitoring device 75 and the PCS control unit 50), or may be integrated into one unit (for example, an integrated single PCS control unit 50).

[0046] (5) In the above embodiment, a fire detector is used as an example of the detector 53. However, a leakage detector or a ground fault detector may be used. Also, a pressure detector or the like may be used.

[0047] (6) In the above embodiment, when the detector 53 detects an abnormality, the current interruption flow shown in Fig. 5 is executed. When the module monitoring device 70 or the bank monitoring device 75 detects an abnormality in a storage battery cell 61 or an abnormality in the current, the current interruption flow shown in Fig. 5 may be executed. In this case, the module monitoring device 70 or the bank monitoring device 75 may notify the PCS panel control unit 40 of the abnormality (S30). The module monitoring device 70 and the bank monitoring device 75 are examples of the "detector" in the present invention.

[0048] 1 Power system 10 Energy storage system 30 PCS 40 PCS control unit (control device) 50A to 50C Battery panel 51 Battery bank 53 Detector 55 Battery panel control unit (control device) 65 Circuit breaker 70 Module monitoring device 75 Bank monitoring device (control device)

Claims

1. An energy storage system comprising: a PCS; a plurality of battery banks connected in parallel to the PCS via a power line; a circuit breaker provided in each of the plurality of battery banks; a detector that detects an abnormality in the energy storage system; and a control device, wherein when the control device detects an abnormality in the energy storage system, it stops the PCS and then opens the circuit breaker to disconnect the battery bank from the power line.

2. An energy storage system according to claim 1, comprising a plurality of battery panels each accommodating the battery banks, wherein, when the control device detects an abnormality in any of the plurality of battery panels, it stops the PCS and then disconnects the battery banks in all of the battery panels.

3. An energy storage system as described in claim 1, comprising a plurality of battery panels each accommodating the battery banks, wherein, when the control device detects an abnormality in any of the plurality of battery panels, it stops the PCS and then disconnects the battery bank in the battery panel that detected the abnormality, while maintaining the connection of the battery banks in the other battery panels.

4. An energy storage system according to claim 2 or 3, wherein the detector is a fire detector that detects a fire in the battery panel.

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