Monitoring system for power storage bank

Abstract

To provide a technology for enabling identification of a module monitoring device at which a communication error has occurred to contribute to early recovery from the communication error.SOLUTION: A monitoring system for a power storage bank 21 composed of a plurality of power storage modules 60, comprises: a plurality of module monitoring devices 70 that are installed at the plurality of power storage modules 60, respectively, to monitor states of the power storage modules 60; and a bank monitoring device 65 for monitoring a state of the power storage bank 21, in which the bank monitoring device 65 is daisy chain-connected to the plurality of module monitoring devices 70 via communication lines. When a communication error has occurred between the bank monitoring device and the module monitoring devices 70, the bank monitoring device 65 performs response confirmation while designating communication partners in order from the module monitoring device 70 on the near side on a communication path and identifies, as a communication error occurrence location, the module monitoring device 70 returning no responses at first.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a monitoring system for an electricity storage bank. [Background technology]

[0002] The introduction of energy storage systems is being promoted to achieve efficient energy management. When the demand for electricity is lower than the supply, the energy storage system charges a storage bank with surplus electricity, and when the demand for electricity exceeds the supply, the system discharges the storage bank to make up for the power shortage. Patent Document 1 is a document disclosing technology related to energy storage systems. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-65595 Summary of the Invention [Problem to be solved by the invention]

[0004] A storage bank is generally configured with multiple storage modules (units of multiple storage cells) connected in series, and a module monitoring device is provided for each storage module to monitor the status of the storage module.

[0005] When module monitoring devices are connected in a daisy chain, it can be difficult to identify the location of a communication error, and there is concern that it may take a long time to recover from the communication error.

[0006] An object of the present invention is to provide a technology that enables identification of a module monitoring device in which a communication error has occurred and contributes to early recovery from the communication error. [Means for solving the problem]

[0007] According to one embodiment of the present invention, a monitoring system for a storage bank consisting of a plurality of storage modules comprises a plurality of module monitoring devices installed in the plurality of storage modules, respectively, for monitoring the status of the storage modules, and a bank monitoring device for monitoring the status of the storage bank, and the bank monitoring device and the plurality of module monitoring devices are daisy-chain connected via communication lines. If a communication error occurs between the bank monitoring device and the module monitoring device, the bank monitoring device will specify the communication partner starting from the module monitoring device that is closest on the communication path and check the response in order, and will identify the module monitoring device that first does not respond as the location where the communication error occurred. [Effects of the Invention]

[0008] This technology makes it possible to identify the module monitoring device in which a communication error has occurred, allowing for early recovery from the communication error. [Brief explanation of the drawings]

[0009] [Figure 1] Energy storage system block diagram [Figure 2] Battery panel block diagram [Figure 3] Perspective view of the energy storage module [Figure 4] A diagram showing the communication method between the bank monitor and the module monitor. [Figure 5] Diagram showing the monitoring IC communication sequence [Figure 6] Communication command diagram [Figure 7] Module monitoring device block diagram [Figure 8] A diagram showing communication using the second communication command [Figure 9] A diagram showing communication using a first communication command [Figure 10] A diagram showing how to identify the location of a communication error DETAILED DESCRIPTION OF THE INVENTION

[0010] (Outline of this embodiment) (1) According to one embodiment of the present invention, a monitoring system for a storage bank consisting of a plurality of storage modules includes a plurality of module monitoring devices installed in the plurality of storage modules, respectively, for monitoring the status of the storage modules, and a bank monitoring device for monitoring the status of the storage bank, and the bank monitoring device and the plurality of module monitoring devices are daisy-chained via communication lines.

[0011] When a communication error occurs between the bank monitoring device and the module monitoring device, the bank monitoring device designates a communication partner starting from the module monitoring device that is closer on the communication path, and checks for a response in order, and identifies the module monitoring device that does not respond first as the location where the communication error occurred. In the monitoring device for a power storage bank described in (1), any configuration other than the above is optional and may be any configuration.

[0012] The energy storage bank monitoring system according to one embodiment of the present invention can identify a module monitoring device in which a communication error has occurred and can quickly recover from the communication error, thereby contributing to efficient operation of the energy storage bank.

[0013] (2) In the energy storage bank monitoring system described in (1), the communication error may be a communication error due to a first communication command that is sent from the bank monitoring device to all module monitoring devices connected in a daisy chain without specifying a communication partner. In the energy storage bank monitoring system described in (2), any configuration other than the above is optional and may be any configuration.

[0014] The first communication command is a command that does not specify the communication partner, making it difficult to identify the location of the communication error. The energy storage bank monitoring system described in (2) can solve the technical problem specific to communication using the first communication command (the problem of difficulty in identifying the location of the communication error).

[0015] (3) In the energy storage bank monitoring system described in (1) or (2) above, the bank monitoring device may determine the communication status of each of the module monitoring devices by confirming a response using an ID number assigned according to the number of connected module monitoring devices. In the energy storage bank monitoring system described in (3), any configuration other than the above is optional and may be used.

[0016] The energy storage bank monitoring system described in (3) can check the communication status using the ID number. Since the ID number is assigned according to the number of connected module monitoring devices, it is possible to check the communication status and also determine the number of connected module monitoring devices that can communicate normally.

[0017] (4) In the energy storage bank monitoring system described in (3) above, the energy storage module may include a plurality of energy storage cells connected in series. The module monitoring device may include a balancing circuit that balances the capacitance between the energy storage cells. The first communication command may be a command related to a balancing operation of the energy storage cells. In the energy storage bank monitoring system described in (4) above, any configuration other than the above is optional and may be used.

[0018] If this technology is applied to the energy storage bank monitoring system described in (4), when a communication error occurs, the module monitoring device causing the error can be identified and repaired or replaced, thereby eliminating the communication error. Therefore, after the communication error is resolved, the bank monitoring device can reliably transmit a balancing operation command to all module monitoring devices. This allows the balancing operation of the energy storage cells to be performed simultaneously in all energy storage modules, and the energy storage cells can be managed to maintain a state with minimal capacity difference. This allows the performance of the energy storage cells to be maximized and is also effective in preventing energy storage cell degradation.

[0019] <Embodiment 1> 1. Description of Energy Storage System 10 Figure 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 electricity. The power grid 1 may be that of a power utility company, or it may be an independent power grid that consists of the stand-alone operation output of a large power conditioner.

[0020] The energy storage system 10 includes a battery panel 20 that stores energy, a PCS panel 30, and a remote monitoring panel 50. PCS is an abbreviation for Power Conditioning System.

[0021] The PCS panel 30 includes a power conversion unit 40, a control unit 45, and a housing 31 that houses them. The power conversion unit 40 is a bidirectional power converter capable of reverse conversion (DC to AC) and forward conversion (AC to DC). The power conversion unit 40 is connected to the power grid 1 via an interconnection switch 43.

[0022] The inverse conversion operation (DC to AC) of the power conversion unit 40 allows the battery panel 20 to be discharged and AC power to be supplied to the power grid 1. In addition, the forward conversion operation (AC to DC) of the power conversion unit 40 allows the battery panel 20 to be charged with AC power from the power grid 1.

[0023] In this embodiment, the capacity of the PCS board 30 is ensured by providing a plurality of three power conversion units 40A to 40C in parallel.

[0024] The control unit 45 includes, for example, a CPU (Central Processing Unit) and a memory for storing various data. The control unit 45 controls the power conversion units 40A to 40C in response to commands from a higher-level system such as an EMS (Energy Management System) and adjusts the supply and demand of power.

[0025] Specifically, when the demand for electricity is lower than the supply, the excess electricity is used to charge the battery panel 20 of the energy storage system 10, and when the demand for electricity exceeds the supply, the power shortage is made up by discharging the battery panel 20 of the energy storage system 10.

[0026] By exchanging power with the power grid 1 and adjusting supply and demand, it is possible to improve the efficiency of energy use and contribute to energy conservation.

[0027] The remote monitoring panel 50 is equipped with a communication board 55 for wireless communication with the remote monitoring device 100. The remote monitoring device 100 remotely monitors the state (SOC and temperature) of the battery panel 20 by communication via the remote monitoring panel 50. The remote monitoring panel 50 also has a communication function with a higher-level system, and commands from the higher-level system are notified to the control unit 45 of the PCS panel 30 via the remote monitoring panel 50.

[0028] 2. Configuration of the battery panel 20 2 is a block diagram of the battery panel 20. The battery panel 20 is composed of a power storage bank 21, a thermistor 22 that detects the temperature of the battery panel 20, a panel air conditioner 23 that controls the temperature of the battery panel 20, a fire detection system 24, a battery panel monitoring unit 25, and a housing 20A that houses these components.

[0029] The battery panel monitoring unit 25 includes a control device 26, a memory unit 27, a display unit 28, and a DC power supply unit 29. The battery panel monitoring unit 25 collects information from within the battery panel and communicates with the PCS panel 30 and the remote monitoring device 100.

[0030] The power storage bank 21 is composed of a plurality of power storage modules 60 connected in series, a current sensor 63, a fuse 64, a relay switch, a bank monitoring device 65, and a plurality of module monitoring devices 70. The current sensor 63 measures the current of the power storage bank 21, and the relay switch cuts off the current of the power storage bank 21.

[0031] 3, the power storage module 60 is a unit formed by fixing a plurality of power storage cells 61 connected in series to a frame 62. Various types of cells can be used as the power storage cells 61, such as non-aqueous electrolyte secondary battery cells such as lithium ion secondary batteries, capacitors, NAS battery cells, and redox flow battery cells, as long as they are capable of storing electricity (capable of repeated charging and discharging).

[0032] 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 power storage cell 61.

[0033] The bank monitoring device 65 monitors the current of the storage module 60 based on the measurement value of the current sensor 63, and monitors the temperature of each storage module 60 and the cell voltage of each storage cell 61 through communication with the module monitoring device 70.

[0034] The power storage bank 21 is connected to a power line (main circuit) L0 via a fuse 64 and a relay SW. The power storage bank 21 may be configured as a single bank or multiple banks. Fig. 2 shows a configuration of three banks.

[0035] 3. Communication method and communication sequence FIG. 4 is a diagram showing a communication system between the bank monitoring device 65 and the module monitoring device 70. The bank monitoring device 65 includes a CPU 66, a communication IC 67 for signal conversion, and a pulse transformer 68. The module monitoring device 70 includes a pulse transformer 71, a monitoring IC 75, and an EEPROM 76.

[0036] The EEPROM 76 stores information such as the serial number of the module monitoring device 70, the number of cells in the power storage module 60, and the type of the cells 61.

[0037] The bank monitoring device 65 and the multiple module monitoring devices 70 are daisy-chained via a communication line L. A daisy-chain connection is a form in which multiple devices are connected in a chain, and is also called a cascade connection. FIG. 4 shows an example in which 18 module monitoring devices 70 are daisy-chained. This is just one example, and the number of connections may be other than 18. The ID attached to the bottom of the square box representing each module monitoring device 70 is the identification number of the module monitoring device 70.

[0038] The bank monitoring device 65 communicates with each module monitoring device 70 via a bucket brigade network (specifically, insulated two-wire differential SPI communication). SPI is an abbreviation for Serial Peripheral Interface.

[0039] In this communication method, the CPU 66 of the bank monitoring device 65 communicates directly with the monitoring IC 75 of the module monitoring device 70 via the communication IC 67, pulse transformer 68, and pulse transformer 71. This eliminates the need for a CPU or its peripheral circuits (such as a power supply circuit or reset circuit for the CPU) in the module monitoring device 70, thereby reducing the cost of the module monitoring device 70. Furthermore, the use of pulse transformers 68 and 71, which essentially have an infinite lifespan, improves long-term reliability compared to the use of photocouplers, which have a finite lifespan. Electrical isolation between the bank monitoring device 65 and the module monitoring device 70 ensures user safety (electric shock protection). In particular, in this example, the use of two pulse transformers 68 and 71 allows the remote monitoring panel 50 to be double-insulated against the battery voltage of the power storage bank 21.

[0040] 5 shows the communication sequence of the monitoring IC 75. The communication sequence is made up of four steps (1) to (4). The implementation items of each step are shown below.

[0041] (1) Startup sequence This is the startup process when the power is turned on or restarted, and the following is executed. The bank monitor 65 sends a start command to the monitor IC 75 of the module monitor 70. The bank monitoring device 65 checks the number of connections of the module monitoring device 70 based on the response result of the start-up command. After confirming the number of connections, the bank monitoring device 65 sends an ID assignment command to each monitoring IC 75. The ID assignment command is a command that assigns an ID to each monitoring IC 75 according to the number of connections. When the ID assignment command is received, the ID (identification number) specified by the ID assignment command is saved in the register of each monitoring IC 75. The register contents are initialized every time the device is started. For example, if the number of connections to the module monitoring device 70 is 18, ID numbers from ID=1 to ID=18 are assigned to the 18 monitoring ICs 75 (see Figure 4).

[0042] (2) Read sequence After startup, the monitoring IC 75 reads data from the EEPROM 76. Strictly speaking, the monitoring IC 75 does not actively read data, but rather the CPU 66 transmits an EEPROM read command to the monitoring IC 75 of each module monitoring device 70 in turn, causing the monitoring IC 75 to read the stored contents from the EEPROM 76 and transmit (response to) the read result to the CPU 66 of the bank monitoring device 65. <Data> Module monitoring device 70 serial number -Type of storage cell 61 -61 storage cells

[0043] (3) Continuous monitoring sequence The monitoring IC 75 monitors and controls the state of the power storage module 60 . <Monitoring and control items> - Acquisition of cell voltage of storage cells and temperature information of storage modules Balancer operation Various data processing

[0044] (4) Pre-restart wait sequence After waiting for 3 seconds, return to (1) and restart.

[0045] <When communication is normal> The transitions are made in the order of (1) ⇒ (2) ⇒ (3), and thereafter (3) is repeated at predetermined intervals (for example, several seconds).

[0046] <If a communication error occurs> If (1) or (2) does not transition to (3) within the specified time (startup timeout), or if communication loss continues for the specified time in (3), it transitions to (4) and then transitions to (1) to restart.

[0047] If the state transitions to (4), then to (1), and then does not transition to (3) within the specified time, the bank monitoring device 65 will issue a communication error to the battery panel monitoring unit 25 and stop communication with the module monitoring device 70.

[0048] FIG. 6 is a diagram showing communication specifications during the continuous monitoring sequence. There are two types of communication commands during the continuous monitoring sequence (commands sent from the bank monitoring device 65 to the module monitoring device 70): a first communication command and a second communication command.

[0049] The first communication command is a command (broadcast command) that does not specify a communication partner and transmits the same command to all of the daisy-chain connected module monitoring devices 70. The first communication command is, for example, an instruction regarding the balancing operation of the energy storage cells 61.

[0050] The balancing operation is a control to equalize the capacities by discharging the cell with the higher voltage when a difference in capacity (voltage) occurs between cells. In this example, as shown in FIG. 7, a module monitoring device 70 is equipped with a balancing circuit 72 that performs balancing operations for each storage cell 61, and analog filters 73A and 73B. A monitoring IC 75 has a first digital filter 77A, a first voltage measurement unit 78, a second digital filter 77B, a second voltage measurement unit 79, and a control circuit 80. The first analog filter 73A and the second analog filter 73B suppress high-frequency noise from the measurement value (measured voltage value of the storage cell), and the first digital filter 77A and the second digital filter 77B suppress low-frequency noise.

[0051] The bank monitoring device 65 instructs each module monitoring device 70 to perform a balancing operation at a predetermined timing (such as when a certain period of time has passed since the previous balancing operation) and to stop voltage measurement operations by the digital filter circuits of both the measurement system and monitoring system of the monitoring IC 75 (first digital filter 77A, first voltage measurement unit 78, second digital filter 77B, and second voltage measurement unit 79) during the balancing operation. This is because voltage measurement values ​​become unstable during the balancing operation. The second voltage measurement unit 79 is installed to provide redundancy in voltage measurement.

[0052] The second communication command is a command for identifying the module monitoring device 70 as the communication partner and communicating individually (individual communication command). The second communication command includes, for example, an instruction to acquire the temperature of the power storage module 60 and the cell voltage of each power storage cell 61.

[0053] 6, in the continuous monitoring sequence, the first and second communication commands are interspersed, and if communication fails, the same command is repeatedly retried. If the time limit elapses after sending a communication command and the time-out occurs, the bank monitoring device 65 determines that a communication error has occurred.

[0054] <Command transmission using the second communication command and communication error> 8 shows an example in which a second communication command is sent to the module monitoring device 70 with ID=16. The second communication command sent from the bank monitoring device 65 is sent to the module monitoring device 70 with ID=16 via the module monitoring device 70 with ID=18 and the module monitoring device 70 with ID=17. Upon receiving the second communication command, the module monitoring device 70 with ID=16 returns a response confirmation to the bank monitoring device 65, in the opposite order from when the command was sent, while relaying the command through the module monitoring devices 70 with ID=17 and ID=18. If the bank monitoring device 65 receives a response confirmation from the module monitoring device 70 with ID=16 within the time limit, the bank monitoring device 65 determines that the communication is normal; if the bank monitoring device 65 does not receive a response confirmation, the bank monitoring device 65 determines that a communication error has occurred.

[0055] Since the second communication command is a communication that specifies the communication partner, even if it is determined that a communication error has occurred, it can be determined that the location where the communication error occurred is the module monitoring device 70 with ID=16, which is the communication partner.

[0056] <Command transmission using the first communication command and communication error> The first communication command is transmitted from the bank monitoring device 65 to all module monitoring devices 70 connected in a daisy chain, without specifying the communication partner. Specifically, as shown in Fig. 9, the first communication command is transmitted in succession in a bucket brigade fashion from the module monitoring device 70 with ID=18 that is closer to the bank monitoring device 65 to the module monitoring device 70 with ID=1 that is farther away.

[0057] When the module monitor 70 with ID=1 receives the first communication command, it returns a response confirmation to the bank monitor 65 while relaying the command through each module monitor 70 in a manner that traces the route in reverse.

[0058] If the bank monitoring device 65 receives a response confirmation from the module monitoring device 70 with ID=1 within the time limit after sending the first communication command, it determines that the communication is normal, and if no response confirmation is received, it determines that there is a communication error.

[0059] Since the first communication command does not specify the communication partner, even if a communication error occurs, it is not possible to determine in which module monitoring device 70 the error occurred.

[0060] FIG. 10 is a diagram illustrating a method for identifying the location of a communication error. If a communication error occurs with the first communication command during the continuous monitoring sequence, the bank monitoring device 65 checks the communication status by selecting the module monitoring device 70 connected in the daisy chain that is closest on the communication path as the communication partner. If the communication status is confirmed, the bank monitoring device 65 selects the next module monitoring device 70 as the communication partner and checks the communication status. By repeating this communication check operation, it is possible to identify the module monitoring device 70 in which the communication error occurred.

[0061] For example, if a communication error occurs, the bank monitor 65 first designates the first module monitor 70, which is closest to the bank monitor 65 on the communication path, as the communication partner and sends an ID confirmation command. Since the first module monitor 70 has ID=18, the ID confirmation command is initially sent specifying ID=18.

[0062] When the first module monitor 70 receives the ID confirmation command from the bank monitor 65, it returns a response confirmation to the bank monitor 65.

[0063] When the bank monitoring device 65 confirms the response confirmation, it recognizes that the communication status of the first bank monitoring device 65 is normal.

[0064] The bank monitor 65 then sends an ID confirmation command to the second module monitor 70 specifying ID=17.

[0065] The ID confirmation command sent from the bank monitor 65 is sent to the second module monitor 70 (ID=17) via the first module monitor 70 (ID=18).

[0066] When the second module monitor 70 receives the ID confirmation command, it returns a response confirmation to the bank monitor 65 via the first module monitor 70 (ID=18).

[0067] When the bank monitoring device 65 confirms the response confirmation, it recognizes that the communication status of the second bank monitoring device 65 (ID=17) is normal.

[0068] In this way, the bank monitoring device 65 individually checks the communication status of each module monitoring device 70 connected in a daisy chain by checking responses using IDs in order from the closest side on the communication path.

[0069] 10, the module monitoring devices 70 with IDs 18 to 3 successfully confirmed the response, while the module monitoring device 70 with ID 2 failed to confirm the response. Therefore, the location where the communication error occurred can be identified as the module monitoring device 70 with ID 2.

[0070] When the bank monitoring device 65 identifies the module monitoring device 70 in which the communication error has occurred, it notifies the ID of the module monitoring device 70 in which the communication error has occurred when it issues a communication error report.

[0071] In this example, information about the communication error is transmitted from the bank monitoring device 65 to the battery panel monitoring unit 25 together with the ID of the error module, and is displayed as an error message on the display unit 28. This eliminates the need to identify the location of the communication error, allowing for early recovery from the communication error.

[0072] In this example, the communication status is confirmed using an ID number assigned according to the number of module monitoring device 70 connections, so in addition to confirming communication, it is possible to determine the number of module monitoring device 70 connections that can communicate normally (in the above example, 18-2 means 16 levels are normal).

[0073] Since the module monitoring devices 70 are daisy-chain connected, it is not possible to determine the communication status of the module monitoring device 65 (in the above example, the module monitoring device with ID=1) ahead of the module monitoring device 70 where the communication error occurred.

[0074] 4.Effects This configuration enables early recovery from a communication error, thereby shortening the downtime caused by the communication error and contributing to efficient operation of the battery panel 20 and the energy storage system 10.

[0075] <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.

[0076] (1) In the above embodiment, an example was shown in which a module monitoring device that caused a communication error that occurred during a continuous monitoring sequence was identified. If the location of the communication error is unknown, the present technology may be applied to identify the module monitoring device that caused the error, regardless of the sequence of the monitoring IC.

[0077] (2) In the above embodiment, when identifying the module monitoring device 70 with a communication error, a response confirmation was performed using an ID. However, if it is possible to determine whether the communication status is good or bad, a response confirmation may be performed using information other than an ID.

[0078] (3) In the above embodiment, ID numbers are assigned in descending order starting from the module monitor 70 closest to the bank monitor 65, but ID numbers may be assigned in ascending order.

[0079] 1 Power system 10 Energy Storage Systems 20 Battery panel 21 Energy storage bank 65 Bank Monitoring Device 70 Module Monitoring Device

Claims

1. A monitoring system for a power storage bank consisting of a plurality of power storage modules, a plurality of module monitoring devices that are installed in the plurality of power storage modules, respectively, and that monitor the states of the power storage modules; a bank monitoring device that monitors the state of the battery bank, wherein the bank monitoring device and the plurality of module monitoring devices are daisy-chain connected via a communication line; In a monitoring system for a power storage bank, when a communication error occurs between the bank monitoring device and the module monitoring device, the bank monitoring device designates a communication partner from the module monitoring device that is closest on the communication path and checks for a response in order, and identifies the module monitoring device that does not respond first as the location where the communication error occurred.

2. The monitoring system for the power storage bank according to claim 1, In the energy storage bank monitoring system, the communication error is a communication error caused by a first communication command that does not specify a communication partner and is sent from the bank monitoring device to all module monitoring devices connected in a daisy chain.

3. The monitoring system for the power storage bank according to claim 1 or 2, The bank monitoring device determines the communication status of each of the module monitoring devices by confirming a response using an ID number assigned according to the number of connections of the module monitoring devices.

4. The monitoring system for the power storage bank according to claim 2, the energy storage module includes a plurality of energy storage cells connected in series; the module monitoring device includes a balancing circuit that balances the capacitances of the storage cells; The first communication command is a command regarding a balancing operation of the energy storage cells.

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