JP7807985B2 - Energy storage system - Google Patents

Description

This disclosure relates to an energy storage system.

Traditionally, stationary energy storage systems have been used in addition to commercial power sources to power electrical equipment installed in buildings.

Regarding such stationary energy storage systems, for example, Japanese Patent Application Laid-Open No. 2017-085781 (Patent Document 1) discloses technology that allows a user to manually set operations such as prioritizing charging of the energy storage devices included in the energy storage system or prioritizing power supply to other energy storage devices such as electric vehicles.

Japanese Patent Application Laid-Open No. 2017-085781

Stationary energy storage systems may be equipped with an interface that accepts user instructions via a communications network in order to operate in accordance with the user's intentions, as described above. However, if a communication failure in the communications network causes a delay in communication, the receipt of the user's instructions may be delayed, or the user's instructions may not be received at all while the communication failure is occurring. As a result, changes to the energy storage system's operation may not be implemented at the time the user intended.

This disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an energy storage system that allows the user to change its operation at the timing intended by the user.

An energy storage system according to one aspect of the present disclosure includes an energy storage device installed in a building that can exchange power with electrical equipment installed in the building, a control device that performs one of a plurality of operations related to charging and discharging the energy storage device, and a terminal that can communicate with the control device. When the terminal receives an operation to switch from a first operation to a second operation among the plurality of operations, the terminal generates a switching instruction using information indicating the end time of the first operation and information indicating that the second operation will be performed after the first operation, and transmits the generated switching instruction to the control device.

In this way, the terminal sends a switching instruction to the control device that includes information indicating the end time of the first operation and information indicating that the second operation will be performed after the first operation. Therefore, even if a communication delay occurs after that, the control device can switch from the first operation to the second operation in accordance with the received switching instruction. This allows the user to switch operations at the timing intended.

In one embodiment, when the control device receives a switching instruction from the terminal, it ends the first operation at the end time and performs the second operation.

In this way, the control device can receive a switching instruction from the terminal and switch from the first operation to the second operation in accordance with the received switching instruction, even if a delay occurs in communication afterwards. This allows the operation to be switched at the timing intended by the user.

In one embodiment, the information indicating the end time of the first operation includes information about the time at which the switching instruction was generated and information about the period from the time of generation until the first operation is terminated.

In this way, the end time can be obtained using the time when the switching instruction was generated and the period from the time of generation to the end of the first operation, so the operation can be switched at the timing intended by the user even if there is a delay in communication.

This disclosure provides an energy storage system that allows users to change their operation at the timing they desire.

1 is a diagram illustrating an example of an overall configuration of a power storage system. 10A and 10B are diagrams for explaining the occurrence of a delay in an instruction to switch an operation mode due to a communication failure. 10 is a flowchart illustrating an example of a process executed in the server. FIG. 10 is a diagram showing an example of information constituting a switching instruction in a table format. 10 is a flowchart illustrating an example of processing executed in a PCS.

Embodiments of the present disclosure will now be described in detail with reference to the drawings. Note that identical or equivalent parts in the drawings will be designated by the same reference numerals and their descriptions will not be repeated.

Figure 1 is a diagram showing a schematic diagram of an example of the overall configuration of a power storage system 1. A portion of the configuration of the power storage system 1, a distribution board 4, and an electrical load 10 are provided within a building 3. The electrical load 10 within the building 3 is connected via the distribution board 4 to a power grid 2 connected to a commercial power source or the like, and to a power conditioner system (hereinafter referred to as PCS) 30 (described below) of the power storage system 1.

The distribution board 4 is configured to be able to select the power transmission path between the PCS 30 of the energy storage system 1, the power grid 2, and the electrical load 10.

The distribution board 4 can, for example, select a power transmission path for supplying power supplied from the power grid 2 to the electrical load 10 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the PCS 30 of the power storage system 1 to the electrical load 10 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the power grid 2 to the PCS 30 of the power storage system 1 via the distribution board 4. Furthermore, the distribution board 4 can select a power transmission path for supplying power supplied from the PCS 30 of the power storage system 1 to the power grid 2 via the distribution board 4.

The electrical load 10 includes electrical equipment installed inside or outside the building 3. The electrical load 10 includes, for example, lighting devices and various home appliances.

The power storage system 1 includes a solar power generation device 20, a PCS 30, a router 40, a battery unit 70, a server 100, and a mobile terminal 150. The battery unit 70 is installed outside (outdoors) of the building 3. The battery unit 70 may also be installed inside (indoors) of the building 3.

The solar power generation device 20 is composed of, for example, solar panels installed outdoors, such as on the roof of the building 3. The solar power generation device 20 is connected to the PCS 30. The solar power generation device 20 receives sunlight, generates DC power, and supplies the generated DC power to the PCS 30.

The PCS 30 includes various power conversion devices (not shown), a control device 32, and a communication device 34. The PCS 30 converts DC power supplied from at least one of the battery unit 70 and the solar power generation device 20 into AC power and supplies it to the distribution board 4. Alternatively, the PCS 30 supplies DC power supplied from the solar power generation device 20 to the battery unit 70. Alternatively, the PCS 32 converts AC power supplied from the power grid 2 into DC power and supplies it to the battery unit 70.

The control device 32 is composed of a CPU (Central Processing Unit), memory (such as ROM (Read Only Memory) and RAM (Random Access Memory)), and input/output ports for inputting and outputting various signals. The various controls performed by the control device 32 are software processes, that is, programs stored in memory are read by the CPU. The various controls performed by the control device 32 can also be achieved by a general-purpose computer (not shown) executing programs stored in a storage medium. The various controls performed by the control device 32 are not limited to software processes and may be processed by dedicated hardware (electronic circuits).

The communication device 34 is configured to be able to communicate with, for example, the router 40 and the ECU (Electronic Control Unit) 80 of the battery unit 70 via wired or wireless communication. The communication device 34, for example, exchanges predetermined information with the ECU 80. Furthermore, the communication device 34 is configured to be able to communicate with the server 100 via the router 40 and a communication network 6 such as the Internet. The communication network 6 is connected to, for example, a wireless base station 8, which is communicatively connected to the mobile terminal 150. Therefore, the communication device 34 is configured to be able to communicate with the mobile terminal 150 via the router 40 and the communication network 6.

The router 40 is installed within the building 3. In addition to the communication device 34, the router 40 is connected to communication terminals within the building 3, such as personal computers and smartphones, so that wired or wireless communication is possible.

The battery unit 70 includes an ECU 80 and a battery pack (not shown). The battery pack is composed of, for example, multiple cells. The cells are, for example, nickel-metal hydride batteries or lithium-ion batteries with liquid or solid electrolytes. The battery pack is composed of multiple cells connected in series. Note that the battery pack may also be composed of, for example, multiple battery groups connected in series, each of which is made up of a predetermined number of cells connected in parallel.

The battery unit 70 further includes a system main relay (hereinafter referred to as SMR) (not shown) that connects the battery pack and the PCS 30, for example. The ECU 80 controls the operation of the SMR to switch between a conductive state in which the battery pack and the PCS 30 are electrically connected and a cut-off state in which the battery pack and the PCS 30 are electrically cut off. The ECU 80 operates the SMR in response to a control signal received from the control device 32, for example.

Furthermore, the ECU 80 manages the state of the battery pack. For example, the ECU 80 estimates the SOC of the battery pack using the temperature, current, and voltage within the battery pack. The SOC indicates the ratio of the remaining amount of power to the fully charged capacity. Note that various well-known methods can be used to calculate the SOC, such as a method based on current integration (coulomb counting) or a method based on open circuit voltage (OCV) estimation.

The server 100 is a terminal that includes a control device 102, a storage device 104, a communication device 106, and a user interface (hereinafter referred to as UI) 108. The control device 102, storage device 104, communication device 106, and UI 108 are communicatively connected to each other via a communication bus 110.

Like control device 32, control device 102 is configured to include a CPU, memory (ROM, RAM, etc.), and input/output ports for inputting and outputting various signals. Therefore, detailed description thereof will not be repeated.

The storage device 104 stores information regarding the operation of various electrical devices such as the PCS 30, solar power generation device 20, or battery unit 70, as well as information regarding operation instructions and control instructions received from the user.

Communication device 106 is configured to be capable of two-way communication with communication device 34 via communication network 6. Note that the communication target of communication device 106 is not limited to communication device 34, but may also be a PCS communication device connected to a battery unit in a building other than building 3.

The UI 108 includes various input devices such as a keyboard, mouse, or touch panel. The UI 108 outputs operation signals generated by accepting operations from the user to the control device 102. The control device 102 obtains the user's operation instructions using the operation signals input from the UI 108.

When the operation instruction acquired using the operation signal from the UI 108 is an operation instruction for switching the operation mode of the battery unit 70, the control device 102 transmits an instruction for switching the operation mode to the PCS 30. The operation modes of the battery unit 70 include, for example, a charge mode, a discharge mode, and a standby mode. The charge mode is an operation mode in which charging power is supplied from the PCS 30 to the battery pack of the battery unit 70 to charge the battery pack. The discharge mode is an operation mode in which power from the battery pack of the battery unit 70 is supplied to the PSC 30 to discharge the battery pack. The standby mode is an operation mode in which the battery pack is in a standby state without charging or discharging.

The mobile terminal 150 includes a control device, a storage device, a communication device, and a UI (none of which are shown). The functions of the control device, storage device, communication device, and UI of the mobile terminal 150 are similar to the functions of the control device 102, storage device 104, communication device 106, and UI 108 of the server 100. Therefore, detailed descriptions of these will not be repeated.

In a power storage system 1 configured as described above, if a communication failure occurs between communication device 34 and communication device 106, even if communication device 106 transmits a switching instruction to switch the operating mode of the battery unit 70, there may be a delay in communication device 34 receiving the switching instruction.

In this embodiment, communication failures include not only those caused by increased traffic or equipment failures on the communication network 6, but also those caused by equipment failures on the communication path within building 3, such as malfunctioning of the router 40.

Below, we will explain the delay in issuing an instruction to switch operating modes due to a communication failure, with reference to Figure 2. Figure 2 is a diagram for explaining the occurrence of a delay in issuing an instruction to switch operating modes due to a communication failure. Figure 2 shows various control instructions and information exchanged between the server 100, PCS 30, and battery unit 70.

As shown in Figure 2 (A), for example, assume that a communication failure occurs in communication network 6. At this time, as shown in Figure 2 (B), if server 100 receives an operational instruction from the user to switch the operating mode of battery unit 70, server 100 transmits a switching instruction to PCS 30 to switch the operating mode of battery unit 70.

However, if a communication failure occurs and the PCS 30 is delayed in receiving the instruction to switch the operating mode from the server 100, as shown in Figure 2 (C), the operating mode of the battery unit 70 cannot be switched until the switching instruction is received. As a result, as shown in Figure 2 (D), it may not be possible for the user to switch the operating mode of the battery unit 70 at the timing intended.

In this embodiment, when the server 100 receives an operation to switch the operating mode of the battery unit 70, it generates a switching instruction using information indicating the end time of the first operating mode before the change and information indicating that the operating mode can be switched to the second operating mode after the first operating mode, and transmits the generated switching instruction to the control device 32 of the PCS 30. When the control device 32 receives a switching instruction from the server 100, it ends operation in the first operating mode at the end time and operates in the second operating mode.

In this way, even if there is a delay in communication with the server 100 after the control device 32 receives a switching instruction, the control device 32 can switch the operating mode of the battery unit 70 from the first operating mode to the second operating mode in accordance with the received switching instruction. This allows the user to switch operations at the timing intended.

An example of processing executed by the server 100 (specifically, the control device 102 of the server 100) will be described below with reference to Figure 3. Figure 3 is a flowchart showing an example of processing executed by the server 100. The series of processing shown in this flowchart is repeatedly executed by the server 100 at predetermined intervals.

In step (hereinafter, step will be abbreviated as S) 100, server 100 determines whether there is a request to switch the operating mode. For example, server 100 determines that there is a request to switch the operating mode when the user's operation instruction is an operation instruction to switch the operating mode of battery unit 70. If it is determined that there is a request to switch the operating mode (YES in S100), processing proceeds to S102.

At S102, the server 100 acquires the current date and time (hereinafter referred to as the current date and time). The server 100 may acquire the current date and time using, for example, an internal clock device, or may acquire the current date and time by communicating with an external server (for example, an NTP (Network Time Protocol) server) via the communication network 6. The server 100 stores the acquired current date and time in the storage device 104. Processing then proceeds to S104.

At S104, the server 100 sets the end time of the first operating mode from the current time. For example, the server 100 sets the end time of the first operating mode to the period from the current time until the operation of the first operating mode ends. The server 100 may, for example, set the end time of the first operating mode to a predetermined time, or may set the end time of the first operating mode to the time required to switch from the first operating mode to the second operating mode, or may set the end time of the first operating mode based on a delay time caused by a communication failure. The predetermined time may, for example, be on the order of several minutes or several hours. The server 100 stores the set end time of the first operating mode in the storage device 104. Processing then proceeds to S106.

At S106, the server 100 acquires the second operating mode. The server 100 acquires the changed operating mode identified by the user's operation instruction as the second operating mode. The server 100 stores the acquired second operating mode in the storage device 104. The process then proceeds to S108.

At S108, the server 100 generates a switching instruction. The server 100 generates the switching instruction as information that associates the acquired current date and time, the set end time of the first operating mode, and the acquired second operating mode. Figure 4 is a diagram showing an example of the information that constitutes the switching instruction in table format.

As shown in FIG. 4, the server 100 generates a switching instruction by associating the information about the current date and time acquired in S102, the information about the end time of the first operating mode set in S104, and the acquired information about the second operating mode. Then, the process proceeds to S110.

At S110, the server 100 transmits a switching instruction to the communication device 34 of the PCS 30. If it is determined that there is no request to switch the operating mode (NO at S100), this process ends.

Next, an example of the processing executed by PCS 30 (specifically, the control device 32 of PCS 30) will be described with reference to Figure 5. Figure 5 is a flowchart showing an example of the processing executed by PCS 30. The series of processing shown in this flowchart is repeatedly executed by PCS 30 at predetermined intervals.

In S200, the PCS 30 determines whether or not a switching instruction has been received. If it is determined that a switching instruction has been received from the server 100 (YES in S200), processing proceeds to S202.

At S202, the PCS 30 acquires the current date and time of the destination using the received switching instruction. The PCS 30 stores the acquired current date and time in the memory of the control device 32. Processing then proceeds to S204.

In S204, the PCS 30 acquires the second operating mode using the received switching instruction. The PCS 30 stores the acquired second operating mode in the memory of the control device 32. Then, the process proceeds to S206.

In S206, PCS 30 sets the time (hereinafter referred to as the end time) at which to end the first operating mode and switch to the second operating mode. For example, PCS 30 sets the end time to the time obtained by adding the end time to the current date and time. Processing then proceeds to S208.

At S208, the PCS 30 acquires the current time. The method for acquiring the current time is the same as the method for acquiring the current time by the server 100. Therefore, a detailed description thereof will not be repeated. Processing then proceeds to S210.

In S210, PCS30 determines whether the current time has reached the end time. For example, PCS30 determines that the current time has reached the end time if the current time is a time after the end time. If it is determined that the current time has reached the end time (YES in S210), processing proceeds to S212.

In S212, the PCS 30 changes the operating mode of the battery unit 70 to the acquired second operating mode. If it is determined that a switching instruction has not been received (NO in S200), this process ends. If it is determined that the current time has not yet reached the end time (NO in S210), the process returns to S210.

An example of the operation of the energy storage system 1 based on the above structure and flowchart will now be described.

For example, assume that the battery unit 70 is operating in standby mode. In this case, the battery unit 70 remains in a state where it is neither charging nor discharging. When a user's operation instruction is received via the UI 108 of the server 100, and the received operation instruction corresponds to an instruction to change the operation mode to charging mode, the server 100 determines that there is a request to switch the operation mode (YES in S100). Therefore, the current date and time are acquired (S102), and the end time of the first operation mode is set (S104). Based on the received operation instruction, charging mode is acquired as the second operation mode (S106). A switching instruction is generated using the current date and time, the end time of the first operation mode, and the second operation mode (S108), and the generated switching instruction is transmitted to the PCS 30 (S110).

When the PCS 30 receives a switching instruction (YES in S200), it acquires the current date and time of the destination (S202), acquires the second operating mode using the switching instruction (S204), and sets the end time of the first operating mode (S206). Then, it acquires the current time (S208), and determines whether the current time has reached the end time (S210).

If it is determined that the current time has reached the end time (YES in S210), the operation mode is changed to the second operation mode, i.e., charging mode (S212).

As a result, even if a communication failure occurs in the communication network 6 or router 40, causing a delay in receiving the switching instruction, if the delayed time is within the end time, the operating mode will be changed when the current time reaches the end time. This makes it possible to change the operating mode in line with the user's intentions.

As described above, in the energy storage system 1 according to this embodiment, the server 100 transmits to the PCS 30 a switching instruction including information indicating the end time of the first operation mode and information indicating that the second operation mode will be performed after the first operation mode. Therefore, even if a delay occurs in communication after that, the PCS 30 can switch from the first operation mode to the second operation mode in accordance with the received switching instruction. This allows the operation to be switched at the timing intended by the user. Therefore, it is possible to provide an energy storage system that allows the user to change operations at the timing intended by the user.

Furthermore, the power storage system 1 in this embodiment can fulfill two roles: providing value (hereinafter referred to as personal value) such as energy savings (hereinafter referred to as energy saving) and disaster prevention to individuals who own the power storage system, and providing value (hereinafter referred to as societal value) such as the ability to adjust power on the power grid to societies (regions such as cities, towns, and villages) that own multiple power storage systems. Furthermore, when prioritizing one of the roles, the power storage system 1 can flexibly switch fail-safe operations depending on the prioritized role.

For example, when prioritizing the role of providing personal value, the above-mentioned switching instruction can be used to switch to charging mode as a first operation in response to weather information such as a weather warning at the location where the power storage system is installed, and then return to energy-saving automatic control mode as a second mode in which PCS30 operates alone as a fail-safe.

Furthermore, for example, when prioritizing the role of providing social value, when the server 100 is coordinating multiple energy storage systems 1 to operate each energy storage system 1 in a predetermined operating mode (charge mode or discharge mode) as a first mode in order to improve energy efficiency throughout the entire area in which multiple energy storage systems 1 are installed, even if a communication failure occurs, the above-mentioned switching instruction can be used to implement an operation to return to a second operating mode, for example, standby mode. By returning to standby mode, it is possible to avoid charging or discharging occurring in energy storage systems that do not receive control instructions from the server 100.

Modifications will be described below.
In the above embodiment, a configuration in which the battery unit 70 is connected to the PCS 30 has been described as an example, but a bidirectional DC/DC converter may be provided between the PCS 30 and the battery unit 70 to convert (boost or step down) the DC power supplied from the PCS 30 into power capable of charging the assembled battery 90 of the battery unit 70, or to convert (boost or step down) the DC power supplied from the battery unit 70 into power of an appropriate voltage as input power to the PCS 30. The bidirectional DC/DC converter may operate in response to a control signal from the ECU 80, for example, or may operate in response to a control signal from a control device (not shown) of the PCS 30.

Furthermore, in the above embodiment, a configuration in which the solar power generation device 20 and the battery unit 70 are connected to the PCS 30 has been described as an example. However, for example, a vehicle equipped with a power storage device may also be connected to the PCS 30, and DC power may be supplied from the vehicle's power storage device, or the DC power of the vehicle's power storage device may be converted to AC power and supplied.

Furthermore, in the above embodiment, the processing shown in the flowchart in Figure 5 was described as being executed by the control device 32 of the PCS 30, but it may also be executed by the ECU 80 of the battery unit 70.

Furthermore, in the above embodiment, the end time is set in the switching instruction regardless of whether a communication failure occurs between the control device of PCS 30 and server 100. However, server 100 may set the end time of the pre-change operating mode in the switching instruction, for example, when a communication failure occurs between the control device 32 of PCS 30 and server 100. For example, when the response time indicated by a ping value or the like to the control device 32 of PCS 30 is equal to or greater than a predetermined value, server 100 may determine that a delay due to a communication failure has occurred between the control device 32 of PCS 30 and server 100 and set the end time. In this case, the end time may be set according to the response time. For example, the end time may be set to be longer as the response time becomes longer.

Furthermore, in the above embodiment, the UI 108 of the server 100 was described as accepting operational instructions, but when an operational instruction is accepted, the user may be notified of the end time of the current operating mode of the battery unit 70.

Furthermore, in the above-described embodiment, the processing shown in the flowchart of FIG. 3 is described as being executed by the control device 102 of the server 100, but it may also be executed by the control device of the mobile terminal 150 instead of the control device 102 of the server 100.

The above-described modifications may be implemented in whole or in part in appropriate combination.
The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 Energy storage system, 2 Power grid, 3 Building, 4 Distribution board, 6 Communication network, 8 Wireless base station, 10 Electric load, 20 Photovoltaic power generation device, 30 PCS, 32, 102 Control device, 34, 106 Communication device, 40 Router, 70 Battery unit, 80 ECU, 90 Battery pack, 100 Server, 104 Storage device, 108 UI, 110 Communication bus, 150 Mobile terminal.

Claims (2)

a power storage device installed in the building, capable of sending and receiving electric power to and from electrical equipment installed in the building;
a control device that performs any one of a plurality of operations related to charging and discharging the power storage device;
a terminal capable of communicating with the control device,
When the terminal receives an operation to switch from a first operation to a second operation among the plurality of operations, the terminal generates a switching instruction using information indicating an end time of the first operation and information indicating that the second operation will be performed after the first operation, and transmits the generated switching instruction to the control device ;
The information indicating the end time of the first operation includes information about the time at which the switching instruction was generated and information about the period from the time of generation until the first operation is terminated . The energy storage system of claim 1, wherein the control device, when receiving the switching instruction from the terminal, ends the first operation at the end time and performs the second operation.