Energy storage system

Abstract

This prevents the system from continuing to operate under reduced capacity after power grid outages have been resolved. [Solution] The energy storage system of the present disclosure comprises a plurality of energy storage units and a control device that controls the charging and discharging operations of the plurality of energy storage units. Each energy storage unit comprises an uninterruptible power supply, a high-voltage battery that is charged by power supplied from the grid, a group of battery packs, and a high-voltage relay that switches between a connected state and a disconnected state between the high-voltage battery and the group of battery packs. When a power outage occurs in the grid, if the uninterruptible power supply of at least one of the plurality of energy storage units becomes insufficient, the control device forcibly shuts down the entire system or performs limited operation using the energy storage units whose uninterruptible power supplies are not insufficient, and also notifies the system to restart when power supply from the grid is restored.

Description

[[Technical Field]]

[0001] The present disclosure relates to a power storage system. [[Background Art]]

[0002] An uninterruptible power supply used in a power storage system supplies power to a load for a certain period of time to continue operation of the system when a commercial power system experiences an outage. For example, Patent Document 1 describes an uninterruptible power supply of a constant power feeding type. The uninterruptible power supply of Patent Document 1 is a constant power feeding type uninterruptible power supply that is provided between a commercial power system and an important load and supplies AC power to the important load. [[Prior Art Document]] [[Patent Document]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2024-073768 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] For example, in a power storage system such as a large stationary power supply system, containers equipped with a plurality of batteries are connected to each other and operated as a single system. Such a power storage system has an UPS (Uninterruptible Power Supply), which is an ECU power supply, in each container. After a system voltage outage, when the self-sustaining operation by the high-voltage battery is canceled in the power storage system, the power storage system shifts to the discharge operation of the UPS. The UPS in each container may be exhausted at different timings due to capacity differences and load variations. In this case, from the container where the UPS is exhausted, the high-voltage relay is tripped and the ECU (Electronic Control System) is stopped sequentially. If power supply from the grid is resumed before the entire system is completely stopped in a state where it is desired to continue the UPS discharge operation in some containers, a situation may occur in which some high-voltage relays remain in the tripped state, that is, the output operation (i.e., the reduced operation) continues.

[0005] This disclosure was made in view of the above issues and provides a technology that can suppress the continuation of restricted system operation when power grid power is restored after an outage. [Means for solving the problem]

[0006] One aspect of this disclosure is an energy storage system. The energy storage system comprises a plurality of energy storage units and a control device that controls the charging and discharging operations of the plurality of energy storage units. Each energy storage unit comprises an uninterruptible power supply, a high-voltage battery charged by power supplied from the grid, a group of battery packs, and a high-voltage relay that switches between a connected state and a disconnected state between the high-voltage battery and the group of battery packs. In the event of a grid power outage, if the uninterruptible power supply of at least one of the plurality of energy storage units becomes insufficient, the control device will either forcibly shut down the entire system or perform limited operation using the energy storage units whose uninterruptible power supplies are not insufficient, and will also notify the system to restart the energy storage system when power supply from the grid is restored. [Effects of the Invention]

[0007] According to the energy storage system of this disclosure, even if an uninterruptible power supply (UPS) output deficiency occurs in any of the energy storage units during a power outage, the entire system will either shut down, or, if the energy storage units that are not experiencing an output deficiency continue limited operation, the user will be notified of the restart when power is restored. This allows the system to be initialized when power is restored, preventing some energy storage units from restarting with their high-voltage relays still tripped. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the configuration of an energy storage system according to an embodiment of the present disclosure. [Figure 2] This is a timing chart illustrating the state transitions of each part of the energy storage system according to the embodiment of this disclosure. [Figure 3]This is a timing chart showing the state of each module of the energy storage system according to the embodiment of this disclosure and the state of the mediation ECU. [Figure 4] This is a timing chart showing the state of each module and the state of the arbitration ECU in another control example of the energy storage system according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and their descriptions are simplified or omitted.

[0010] Embodiment. Figure 1 is a schematic diagram showing the configuration of the energy storage system according to this embodiment. As shown in Figure 1, the energy storage system 100 includes a grid connection panel 1, a transformer 2, a PCS (Power Conditioning System) 3, an auxiliary equipment panel 4, an arbitration ECU (Electronic Control Unit) 5, and a plurality of containers 10. Each container 10 houses an energy storage unit, and each energy storage unit comprises a high-voltage battery 20, a UPS (Uninterruptible Power Supply) 30, and a plurality of modules 40.

[0011] The grid connection panel 1 is connected to the commercial power grid (hereinafter also referred to as the "grid"). The PCS3 is connected to the grid connection panel 1 via a transformer 2. The PCS3 has an AC / DC conversion function. A high-voltage battery 20 is connected to the PCS3. The grid connection panel 1 is also connected to the auxiliary equipment panel 4. The grid connection panel 1 controls the distribution of grid power between the auxiliary equipment panel 4 and the PCS3. The arbitration ECU 5 is a control device that adjusts the control units and equipment of the energy storage system 100.

[0012] The auxiliary panel 4 is connected to the UPS 30 of each of the multiple containers 10. The UPS 30 of each container 10 is connected to the ECU 41 of the multiple modules 40 within each container 10 via an AC / DC converter 32. The auxiliary panel 4 has the function of switching between power supply from the grid connection panel 1 and power supply from each container 10 supplied via the UPS 30, and appropriately distributing the power supplied via the UPS 30 to the loads in the system.

[0013] The ECU 41 controls the operation of high-voltage relays 43 and 44 that connect each of the battery pack groups 42 in each container 10 to the high-voltage battery 20, thereby switching the state between the high-voltage battery 20 and the battery pack groups 42 between a connected state and a disconnected state.

[0014] Figures 2 and 3 will be used to explain the control operations from the time of a power outage until power is restored. Figure 2 is a timing chart illustrating the state transitions of each part of the energy storage system. Figure 3 is a timing chart showing the state of each module of the energy storage system and its relationship to the arbitration ECU 5.

[0015] Figures 2 and 3 show the transitions in the following order: (a) normal power supply from the system, (b) power outage, (c) power restored, (d) depletion of the self-battery 31 in the UPS 30, and (e) power supply resumed. Figure 3 shows an example of conventional control operation for comparison.

[0016] Figure 2 also shows three containers 10, designated as the first to third, as examples. However, there is no limit to the number of containers 10 in the energy storage system 100. Here, the UPS 30s of the first and second containers 10 are assumed to be in state A, where the charge level of their own batteries 31 is relatively low when a power outage occurs, while the UPS 30 of the third container 10 is assumed to be in state B, where the charge level of its own batteries 31 is higher than in state A. Furthermore, the first and second containers 10 in Figure 2 correspond to the abnormal modules in Figure 3, and the third container 10 corresponds to the normal module.

[0017] In a state where power is normally supplied from the grid in (a) of FIG. 2 and FIG. 3, the grid power is appropriately distributed to the PCS 3 side and the auxiliary equipment panel 4 side by the grid interconnection panel 1. As shown in FIG. 2 and FIG. 3, the PCS 3 is in a charging state, and the grid power is charged into the high-voltage battery 20 (refer to arrow A in FIG. 1). The power distributed to the auxiliary equipment panel 4 is charged into the self-contained battery 31 built in the UPS 30, and is supplied to the ECU 41 of each container 10 via the USP 30 and the AC / DC converter 32 (refer to arrow B in FIG. 1). In this state, the high-voltage relays 43 and 44 in the modules 40 of all containers 10 are connected, and the system is in a normal operating state. The power conditioning stop ECU 5 is also in the normal operation mode. In this state, the upper limit output of the entire power storage system 100 is 1050 kW, and the upper limit input to the power storage system 100 is -1050 kW.

[0018] When a grid power outage occurs in (b), the breaker of the grid interconnection panel 1 is tripped, and the PCS 3 shifts to discharge, that is, a self-sustaining operation state. In this state, the power of the high-voltage battery 20 is supplied to the self-contained battery 31 of the UPS 30 and the ECU 41 of each container 10 via the PCS 3, the transformer 2, the grid interconnection panel 1, and the auxiliary equipment panel 4. In this state, the high-voltage relay in the modules 40 of all containers 10 is connected, and the normal operation state is maintained. For the entire system, discharge corresponding to auxiliary power is possible, and the system state is maintained until the state of charge (SOC) of the high-voltage battery 20 becomes depleted, that is, an insufficient output state occurs.

[0019] The power restoration state in (c) is a state where the power outage continues and the high-voltage battery 20 is depleted. In this state, the PCS 3 stops, the self-sustaining operation is canceled, and the grid connection breaker is tripped. The UPS 30 is switched to the discharge mode, and power is supplied from the self-contained battery 31 to the ECU 41 in each container 10. By the charging from the UPS 30, the high-voltage relays 43 and 44 in each module 40 are maintained in a connected state, and normal operation is maintained. Although the charging and discharging of the power storage system 100 is stopped, the control function of the power storage system 100 is maintained.

[0020] In (d), when the self-battery 31 of the USP 30 in any container 10 is depleted, that is, when the output becomes insufficient (the first and second containers 10 in FIG. 2, and the abnormal module in FIG. 3), the ECU 41 of that container 10 stops, the high-voltage relays 43 and 44 are cut off, and the module 40 enters a system stopped state.

[0021] As shown in FIG. 3, in conventional control, for a container 10 in which the self-battery 31 is not depleted (refer to the third container 10 in FIG. 2 and the normal module in FIG. 3), the high-voltage relays 43 and 44 remain connected and normal operation is maintained until the self-battery 31 is depleted. That is, in conventional control, the entire power storage system continues to operate in degraded operation in which an abnormal module that has been stopped with its high-voltage relay cut off and a normal module that continues normal operation coexist. In conventional control, when power supply from the grid is resumed in step (e) in this state, the high-voltage relays 43 and 44 of the abnormal module remain cut off, operation is resumed while maintaining the degraded operation state, and input and output end up being restricted.

[0022] On the other hand, in the control of the power storage system 100 according to the present embodiment, the grid-trip stop ECU 5 stops the system of the normal module (that is, the third container 10) when a system stop occurs in the abnormal module (that is, the first and second containers 10), and forcibly stops the entire system. When power supply is resumed, the user starts the system. Thereby, the ECUs are initialized, and operation can be normally resumed without restriction, in a state where the high-voltage relays 43 and 44 are connected in all containers 10.

[0023] Thereby, according to the control of the present embodiment, it is possible to suppress a situation in which output is restricted when power supply is resumed after a power outage.

[0024] <Other Control> Figure 4 is a timing chart showing the state of each module and the control state of the arbitration ECU in another control example of the energy storage system. In the example shown in Figure 4, if the self-battery 31 of the USP 30 is depleted in any of the containers 10 (the abnormal module in Figure 4), the arbitration ECU 5 notifies the system to restart. In normal modules where the self-battery 31 of the USP 30 is not depleted, normal operation continues. In this case, the arbitration ECU 5 controls notification devices such as display devices, warning lights, and speakers to notify the user that a system restart is required when power is restored. When power is restored in (e), the user restarts the system, which initializes the ECUs in all modules 40 and returns the high-voltage relays to the connected state. This allows normal operation to start without restrictions when power is restored.

[0025] In the embodiments described above, when numbers such as the number of elements, quantities, amounts, or ranges are mentioned, the energy storage system of this disclosure is not limited to the mentioned numbers unless specifically stated or clearly defined in principle. Furthermore, the structures and the like described in these embodiments are not necessarily essential to the energy storage system of this disclosure unless specifically stated or clearly defined in principle. [Explanation of Symbols]

[0026] 1. System Interconnection Panel 2 Transformers 3 PCS 4. Auxiliary equipment panel 5 Mediation ECU 10 containers 20 High-voltage batteries 30 UPS (Uninterruptible power supply) 31 Self battery 40 modules 41 ECU 42 Battery Pack Groups 43, 44 High-voltage relay 100 Energy Storage Systems

Claims

[Claim 1] Multiple energy storage units, A control device that controls the charging and discharging operations of multiple energy storage units, Equipped with, Each of the aforementioned energy storage units is: Uninterruptible power supply and A high-voltage battery that is charged by power supplied from the grid, Battery pack group, A high-voltage relay that switches between a connected state and a disconnected state between the high-voltage battery and the battery pack group, Equipped with, The control device is If, during a power outage in the aforementioned power grid, the uninterruptible power supply of at least one of the multiple energy storage units experiences insufficient output, Forcibly shut down the entire aforementioned system, The system performs limited operation using energy storage units that are not experiencing output deficiencies from the aforementioned uninterruptible power supply, and notifies the user to restart the energy storage system when power supply from the grid is restored. Energy storage system.

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