Energy storage system

Abstract

To suppress a situation where a control unit (control device) of a power storage system becomes inoperable when a power storage device is opened.SOLUTION: A power storage system comprises: a power storage device for stationary use that supplies power to an electric load; a control device that receives power from each of the power storage device and the other power supplies; a relay disposed so as to locate between the power storage device and the control device and between the power storage device and the electric load, and not to locate between the control device and the power supplies; and an input device that receives input from a user. If a connection request is input to the input device when the relay is in a cut-off state, the control device turns the relay into a connection state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power storage system including a stationary power storage device.

Background Art

[0002] International Publication No. 2015 / 029568 (Patent Document 1) discloses a technique for equalizing cell voltages in a battery pack.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Continuous use is expected for a stationary power storage device. For this reason, a stationary power storage device is basically in a closed-circuit state. However, when maintenance of the power storage device is performed, the power storage device is opened. That is, maintenance is performed in a state where the power storage device is opened (open-circuit state). For example, by setting a relay disposed between the power storage device and a control device (control unit of the power storage system) to an off state, the power storage device becomes non-powered, and it becomes possible to perform processing related to maintenance of the power storage device. Examples of processing related to maintenance include, in addition to equalization of cell voltages in the above-described battery pack, correction of various sensors for acquiring information of the power storage device.

[0005] However, when the relay located between the power storage device and the control device is set to an off state, the control device cannot receive power supply from the power storage device. As a result, the control device may lose power and stop, and may become inoperable.

[0006] This disclosure was made to solve the above-mentioned problems, and its purpose is to prevent the control unit (control device) of the energy storage system from becoming inoperable when the energy storage device is opened. [Means for solving the problem]

[0007] The energy storage system according to this disclosure comprises a stationary energy storage device that supplies power to an electrical load, a control device that receives power from the energy storage device and other power sources, a relay positioned between the energy storage device and the control device, and between the energy storage device and the electrical load, but not between the control device and the power source, and an input device that receives input from a user. When a connection request is input to the input device while the relay is in the off state, the control device sets the relay to the connected state.

[0008] In the above configuration, the control device can receive power from both the energy storage device and other power sources. The power sources other than the energy storage device may include, for example, at least one of the power grid and the power generator. Since the relay is located between the energy storage device and the electrical load, the control device can electrically disconnect the energy storage device from the electrical load circuit by tripping the relay. This puts the energy storage device in an open-circuit state, making it possible to perform maintenance on the energy storage device. Also, since the relay is located between the energy storage device and the control device, when the relay is tripped, power is no longer supplied from the energy storage device to the control device. On the other hand, since the relay is not located between the control device and other power sources, when the relay is tripped, the control device can control the relay while receiving power from other power sources.

[0009] However, the control device cannot always receive power from the power source mentioned above. A malfunction in the power source could cause a power outage (a failure to supply power to the control device). Furthermore, if the power source includes a generator, the generator may not be able to generate sufficient power. Therefore, in the above configuration, when a connection request is received from the user via the input device, the control device connects the relay. The user can check the status of the power source and connect the relay as needed. This reduces the likelihood of the control device becoming inoperable due to power loss.

[0010] In the energy storage system described above, the energy storage device may include a battery pack comprising multiple cells electrically connected to each other. The control device may be configured to perform cell voltage equalization in the battery pack when the relay is in the off state. If a connection request is input to the input device while cell voltage equalization is being performed, the control device may stop cell voltage equalization and then set the relay to the connected state.

[0011] With the above configuration, the control device can automatically equalize the cell voltages in the battery pack. Therefore, it is possible to suppress excessive variations in cell voltages in the battery pack.

[0012] In any of the energy storage systems described above, the input device may be configured to accept a connection request input when a predetermined condition is met, and not to accept a connection request input when the predetermined condition is not met. The predetermined condition may be set to be met when it is predicted that a predetermined amount of power will not be supplied from the power source to the control device.

[0013] In the above configuration, the input device accepts a connection request when it is predicted that the control device will not receive a predetermined amount of power (for example, the power required to keep the control device in operation) from a power source other than the energy storage device. This makes it easier for the user to determine whether or not it is necessary to connect the relay.

[0014] In any of the energy storage systems described above, the input device may be mounted on a portable terminal that can be carried by the user. The portable terminal may be configured to display a button that accepts a connection request input when the predetermined conditions are met. With this configuration, when the predetermined conditions are met, a button that accepts a connection request input is displayed on the portable terminal. This makes it possible for the user to easily and quickly connect the relay. [Effects of the Invention]

[0015] According to this disclosure, it becomes possible to suppress the inability of the control unit (control device) of the energy storage system to operate when the energy storage device is opened. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram illustrating the outline of the energy storage system according to the embodiment of the present disclosure. [Figure 2] This flowchart shows an example of a method for switching the open / closed state (open circuit state / closed circuit state) of an energy storage device according to an embodiment of the present disclosure. [Figure 3] This is a flowchart showing the first display control performed by the input device (portable terminal) of the energy storage system shown in Figure 1. [Figure 4] This is a flowchart showing the second display control performed by the input device (portable terminal) of the energy storage system shown in Figure 1. [Modes for carrying out the invention]

[0017] Embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0018] FIG. 1 is a diagram for explaining the outline of the power storage system according to an embodiment of the present disclosure. Referring to FIG. 1, the power storage system according to this embodiment is applied to a building 100. In this embodiment, the building 100 is a residence (for example, the user's own house). However, it is not limited to this, and the building 100 may be other buildings (such as factories, commercial facilities, etc.).

[0019] The power storage system of the building 100 includes a control device 112, a control unit 122, a control device 250, and various sensors. Each of the control device 112, the control unit 122, and the control device 250 corresponds to a control unit of the power storage system, receives detection results from various sensors, and controls the power supply equipment of the building 100. In addition, the control unit of the power storage system performs wireless communication with the mobile terminal 500.

[0020] As each of the control device 112, the control unit 122, and the control device 250, a computer including a processor, a RAM (Random Access Memory), a storage device, a timer, and a communication I / F (interface) can be adopted. In addition, the mobile terminal 500 also incorporates a computer having a similar configuration. As the processor, for example, a CPU (Central Processing Unit) can be adopted. The storage device is configured to be able to store the stored information. The storage device may include a rewritable non-volatile memory. In each computer, by the processor executing the program stored in the storage device, various processes (for example, refer to FIGS. 2 to 4) are executed. However, these various processes are not limited to being executed by software, and can also be executed by dedicated hardware (electronic circuits).

[0021] The mobile terminal 500 is carried by a user. In this embodiment, a smartphone equipped with a touch panel display is adopted as the mobile terminal 500. The touch panel display functions as an input device that receives input from the user. Also, the touch panel display functions as a display device that displays information to the user. Application software for using the power storage system is installed in the mobile terminal 500. However, it is not limited to this, and any mobile terminal 500 can be adopted as the mobile terminal 500, and a laptop, a tablet terminal, a wearable device (for example, a smartwatch, smart glasses), or an electronic key can also be adopted.

[0022] The control device 112, the control unit 122, and the control device 250 are connected via, for example, a bus (not shown) and communicate with each other by wire. In this embodiment, the mobile terminal 500 and the control unit 122 communicate directly, but the mobile terminal 500 and the control device 250 do not communicate directly. The exchange of information between the mobile terminal 500 and the control device 250 is performed via the control unit 122. Thereby, the confidentiality of the information security of the control device 250 is improved. However, it is not limited to this, and the mobile terminal 500 may be configured to be able to communicate directly with each of the control device 112, the control unit 122, and the control device 250.

[0023] In this embodiment, the control device 112, the control unit 122, and the control device 250 are respectively housed in the power conversion unit 110, the PCS 120, and the power storage pack 200 described below.

[0024] The power storage system of the building 100 includes a power conversion unit 110, a PCS (Power Conditioning System) 120, and a distribution board 130. A stationary power storage pack 200 and a power generation device 300 are provided in the building 100. The power storage pack 200 is electrically connected to the power conversion unit 110. The power generation device 300 is electrically connected to the PCS 120.

[0025] The power conversion unit 110 includes a DC / DC converter 111 and a control device 112 that controls the DC / DC converter 111. The DC / DC converter 111 is a bidirectional DC / DC converter that performs bidirectional power conversion (e.g., voltage transformation) between the PCS 120 and the energy storage pack 200. The DC / DC converter 111 may also be a step-up / step-down chopper type bidirectional DC / DC converter.

[0026] Note that the power conversion unit 110 is not a mandatory component and may be omitted. For example, the function of the DC / DC converter 111 may be provided by the circuit section 121 of the PCS 120.

[0027] PCS120 is electrically connected to the power grid PG. The power grid PG includes the power grid, power generation facilities, and substations. The power grid is constructed by transmission and distribution facilities. The power grid PG supplies power to a designated area. Building 100 is located within this designated area. The power grid PG supplies AC power (e.g., single-phase or three-phase AC power) to PCS120.

[0028] The PCS120 includes a circuit unit 121 and a control unit 122 that controls the circuit unit 121. The circuit unit 121 includes various circuits for power conditioning processing (e.g., power conversion and input / output adjustment). In this embodiment, the circuit unit 121 includes a DC / DC converter and an AC / DC conversion circuit (inverter). However, the circuit configuration of the circuit unit 121 can be changed as appropriate. Power is input to the circuit unit 121 from the power grid PG, the power generator 300, and the DC / DC converter 111 (on the energy storage pack 200 side). The circuit unit 121 also outputs power to the DC / DC converter 111 and the distribution board 130. The circuit unit 121 converts the AC power received from the power grid PG into DC power and outputs the DC power to the DC / DC converter 111 (on the energy storage pack 200 side).

[0029] The power generation device 300 generates electricity using natural energy or fuel and outputs the generated electricity to the circuit section 121 of the PCS 120. The power generation device 300 according to this embodiment includes a solar panel installed on the roof of the building 100. The solar panel generates electricity using sunlight. The solar panel is a naturally variable power source whose power output fluctuates depending on weather conditions. However, the power generation device 300 is not limited to a solar panel and may include other power generation devices (for example, a wind power generation device or a hydroelectric power generation device).

[0030] The distribution board 130 receives power (e.g., single-phase or three-phase AC power) from the circuit section 121 of the PCS 120. The circuit section 121 converts the power received from the power grid PG, the power generator 300, and the DC / DC converter 111 into power suitable for the distribution board 130, and outputs the converted power to the distribution board 130. The distribution board 130 is electrically connected to the electrical load 150. The electrical load 150 receives power from the distribution board 130. The electrical load 150 may be directly connected to the distribution board 130. Alternatively, the electrical load 150 may be electrically connected to the distribution board 130 via an outlet (not shown) provided in the building 100. The electrical load 150 may include lighting equipment. The electrical load 150 may include electrical loads used indoors in the building 100 (e.g., air conditioning equipment, information equipment, refrigerators, etc.). The electrical load 150 may include vehicle power supply equipment installed outdoors of building 100.

[0031] The energy storage pack 200 includes an energy storage device 210, a BMS (Battery Management System) 210a, an SMR (System Main Relay) 220, a power conversion circuit 230, and a control device 250. The energy storage device 210 is a stationary energy storage device that supplies power to an electrical load 150. In this embodiment, the energy storage device 210 is a battery pack comprising multiple cells (secondary batteries) that are electrically connected to each other. However, it is not limited to this, and any energy storage device can be used as the energy storage device 210.

[0032] The energy storage device 210 is equipped with a Battery Management System (BMS) 210a that monitors the status of the energy storage device 210. The BMS 210a includes various sensors that detect the status of the energy storage device 210 (e.g., voltage, current, and temperature), and a monitoring IC (integrated circuit) that receives detection signals from the various sensors. In this embodiment, one voltage sensor is provided for each cell that makes up the energy storage device 210 (battery pack).

[0033] The monitoring IC generates a signal indicating the state of the energy storage device 210 (hereinafter also referred to as the "BMS signal") using detection signals from the various sensors, and outputs the generated BMS signal to the control device 250. The control device 250 can acquire the state of the energy storage device 210 (for example, temperature, current, voltage, SOC (State of Charge), and SOH (State of Health)) based on the BMS signal. In this embodiment, the monitoring IC further has a cell voltage equalization function. Specifically, in the energy storage device 210, switches (not shown) are provided between adjacent cells to switch between connecting and disconnecting the electrical circuits connecting those cells. These switches are controlled by the monitoring IC. The monitoring IC equalizes the cell voltage by switching between the closed and open states of each switch.

[0034] The SMR220 switches the connection / disconnection of the circuit connecting the energy storage device 210 and the DC / DC converter 111. The SMR220 includes, for example, a pair of relays (e.g., electromagnetic mechanical relays). These relays are positioned between the energy storage device 210 and the control device 250, and between the energy storage device 210 and the distribution board 130 (electrical load 150), and not between the control device 250 and the PCS120 (power system PG, power generator 300). The SMR220 is controlled by the control device 250. The SMR220 is basically maintained in a closed state (connected state), but is disconnected when predetermined conditions are met (see Figure 2 described later). The number of relays included in the SMR220 can be changed as appropriate.

[0035] In this embodiment, the control unit 122 of the PCS120 switches between grid-connected operation and standalone operation. While power is supplied to the PCS120 from the power grid PG, the control unit 122 puts the building 100 into grid-connected operation mode. During grid-connected operation, the power grid PG and the distribution board 130 are electrically connected. On the other hand, if any malfunction occurs in the power grid PG and the power supply from the power grid PG to the distribution board 130 stops (power outage), the control unit 122 puts the building 100 into standalone operation mode. During standalone operation, the control unit 122 controls the circuit unit 121 so that the power grid PG and the distribution board 130 are electrically disconnected. In standalone operation, power sources other than the power grid PG (energy storage device 210, power generator 300) supply power to the distribution board 130.

[0036] The power conversion circuit 230 is connected to a circuit branched from between the SMR220 and the DC / DC converter 111. The power conversion circuit 230 includes a DC / DC converter. The power conversion circuit 230, for example, steps down the input DC power and outputs the stepped-down DC power to the control device 250. During grid-connected operation, power from the power grid PG is supplied to the power conversion circuit 230 via the PCS120 and the DC / DC converter 111. During standalone operation, power from the energy storage device 210 or the power generator 300 is supplied to the power conversion circuit 230. The power conversion circuit 230 converts the supplied power to power suitable for the operation of the control device 250 (for example, DC power of approximately 12V) and outputs the converted power to the control device 250.

[0037] Building 100 includes an Energy Management System (EMS) 400. In this embodiment, the EMS 400 is configured to communicate with the control unit 122 of the PCS 120. The EMS 400 acquires and records the generated power and demand power of Building 100 over time from an energy meter (not shown) installed in Building 100. The EMS 400 also acquires system information indicating the status of the power grid (supply and demand balance, frequency, etc.) from the TSO (system operator) of the power grid (PG), and predicts whether the power supply from the power grid (PG) to the PCS 120 (and consequently, the control device 250) will be stopped (power outage) based on the system information. The system information may also include disaster prediction information (e.g., earthquake early warnings or typhoon approach information) that predicts the occurrence of disasters that may affect the operation of the power grid (PG). The EMS 400 then notifies the control unit 122 of the time period during which the power grid (PG) is predicted to experience a power outage.

[0038] Furthermore, the EMS400 predicts the power generated by the power generation device 300 (solar panels) based on weather forecast information (weather, temperature, solar radiation intensity, wind speed, etc.). If the power generated by the power generation device 300 exceeds the power demand, resulting in surplus power, the EMS400 sends a signal to the control unit 122 requesting that the surplus power be stored in the energy storage device 210. The EMS400 also predicts whether power above a predetermined standard power will be supplied from the power generation device 300 to the PCS 120 (and consequently, the control device 250) for each predetermined time period. The EMS400 then notifies the control unit 122 of the time periods in which the power supplied from the power generation device 300 to the PCS 120 is predicted to fall below the standard power. The EMS400 may also obtain weather forecast information using a known weather service (for example, a service provided by the Japan Meteorological Agency). The EMS400 manages weather forecast information separately for each region and time.

[0039] As described above, in this embodiment, the EMS 400 transmits to the control unit 122 the future time period during which it is predicted that a predetermined amount of power will not be supplied to the control unit 250 from a power source other than the energy storage device 210 (power grid PG, power generation device 300). However, it is not limited to this, and the control units of the energy storage system (control unit 112, control unit 122, control unit 250) may perform the above prediction instead of the EMS 400.

[0040] Figure 2 is a flowchart illustrating an example of a method for switching the open / closed state (open circuit state / closed circuit state) of the energy storage device 210. In the flowchart, "S" represents a step. The series of processes from S11 to S15 are executed by the control unit 122 (PCS120), and the series of processes from S21 to S23 are executed by the control device 250 (energy storage pack 200). The control unit 122 monitors the success or failure of the interruption condition by repeating the series of processes from S11 to S15.

[0041] Referring to Figure 2 in conjunction with Figure 1, in S11, the control unit 122 determines whether a predetermined shut-off condition is met. In this embodiment, the shut-off condition is met when the control unit of the energy storage system receives a shut-off request from the user, and the shut-off condition is not met when the control unit of the energy storage system does not receive a shut-off request from the user. In this embodiment, the control unit 122 receiving a maintenance execution request signal from the mobile terminal 500 means that the control unit of the energy storage system has received a shut-off request from the user. The maintenance execution request signal will be described later (see Figure 3).

[0042] As long as the blocking condition is not met (NO in S11), the decision in S11 is repeated. On the other hand, if the blocking condition is met (YES in S11), the control unit 122 sends a blocking request signal to the control device 250 in S12 to request blocking of the SMR220, and then in the following S13, it determines whether or not the SMR blocking has been released. While the control unit 122 is receiving the "SMR blocked" status signal (S22), which will be described later, from the control device 250, it determines NO in S13, and when it stops receiving the above status signal, it determines YES in S13.

[0043] If the SMR circuit breaker is not released (NO in S13), the control unit 122 determines in S14 whether a circuit breaker release request has occurred. In this embodiment, it is determined that the above circuit breaker release request has occurred when the control unit of the energy storage system receives a connection request from the user. If the control unit of the energy storage system has not received a connection request from the user, it is determined to be NO in S14. As long as it is determined to be NO in both S13 and S14, steps S12 to S14 are repeated. In this embodiment, the control unit 122 receiving a maintenance cancellation request signal from the mobile terminal 500 means that the control unit of the energy storage system has received a connection request from the user. The maintenance cancellation request signal will be described later (see Figure 4).

[0044] If the above-mentioned request to release the disconnection occurs (YES in S14), the control unit 122 sends a connection request signal to the control device 250 in S15, requesting the connection of the SMR220. In both cases, when YES is determined in S13 and when the process in S15 is executed, the series of processes from S11 to S15 are completed, and the process returns to the first step (S11).

[0045] When the control device 250 receives the aforementioned disconnection request signal (S12) from the control unit 122, it starts a series of processes from S21 to S26. In S21, the control device 250 opens the SMR220 (a pair of relays) to an open state (disconnected state), and then in S22, it sends a "SMR disconnected" status signal to the control unit 122, indicating that the SMR220 is in a disconnected state. The control unit 122 may also send the received "SMR disconnected" status signal to the mobile terminal 500. As a result of the process in S21, the circuit connecting the energy storage device 210 and the DC / DC converter 111 is disconnected, and the energy storage device 210 enters an open circuit state (open state).

[0046] Next, in S23, the control device 250 executes the maintenance process for the opened energy storage device 210. Specifically, the control device 250 causes the monitoring IC (BMS210a) to execute the first and second items described below as maintenance processes.

[0047] The first item is the self-diagnosis of the monitoring IC included in the BMS210a. Specifically, when the energy storage device 210 is de-energized (current 0A), the monitoring IC acquires the OCV (Open Circuit Voltage) of the energy storage device 210 from the voltage sensor included in the BMS210a and outputs the acquired OCV to the control device 250. The monitoring IC self-diagnoses whether it can operate normally based on whether the OCV acquisition was performed successfully. The control device 250 stores the OCV received from the monitoring IC in a memory device, linked to the acquisition time.

[0048] The second item is the equalization of cell voltages in the energy storage device 210. Specifically, the monitoring IC controls the opening and closing of switches provided between adjacent cells in the energy storage device 210 so that the cell voltages in the energy storage device 210 are equalized.

[0049] In the following S24, the control device 250 determines whether the maintenance of the energy storage device 210 is complete. The control device 250 determines whether each item is complete. When any item is completed, the control device 250 saves the information obtained during maintenance (for example, information about abnormalities) along with the time the item was completed to the storage device or transmits it to the mobile terminal 500. If all items are completed, S24 is judged as YES and the process proceeds to S26. If any item is not completed, S24 is judged as NO and the process proceeds to S25.

[0050] In S25, the control device 250 determines whether or not it has received the aforementioned connection request signal (S15) from the control unit 122. If the maintenance of the energy storage device 210 is not complete and the control device 250 has not received the connection request signal (NO in both S24 and S25), steps S22 to S25 are repeated. As a result, the maintenance of the energy storage device 210 (S23) continues. On the other hand, once the maintenance is complete (YES in S24) or the control device 250 receives the connection request signal (YES in S25), the process proceeds to S26.

[0051] In S26, the control device 250 returns the SMR220 (a pair of relays) to the closed state (connected state). If the control device 250 receives a connection request signal, for example, during maintenance of the energy storage device 210, it stops the maintenance and then connects the SMR220. As a result, the energy storage device 210 enters a closed circuit state, and the control device 250 stops sending the "SMR disconnected" status signal (S22) to the control unit 122. Then, the series of processes from S21 to S26 are completed.

[0052] Furthermore, the maintenance items are not limited to the first and second items mentioned above. For example, the maintenance items may consist of only the second item. In addition, the maintenance items may include at least one of the following: correction of various sensors for acquiring information on the energy storage device 210, SOC learning by acquiring the OCV of the energy storage device 210, and estimation of the full charge capacity of the energy storage device 210.

[0053] The display control performed by the mobile terminal 500 will be explained below using Figures 3 and 4. During periods when the mobile terminal 500 does not receive the aforementioned "SMR blocked" status signal (when maintenance is not being performed), it repeatedly executes the series of processes shown in Figure 3. During periods when the "SMR blocked" status signal is received (when maintenance is being performed), it repeatedly executes the series of processes shown in Figure 4.

[0054] Figure 3 is a flowchart showing the first display control performed by the mobile terminal 500. Referring to Figure 3 along with Figure 1, in S61, the mobile terminal 500 determines whether a predetermined first display condition is met. In this embodiment, the first display condition is met when either the building 100 is in grid-connected operation (first grid-connection condition) or the power generated by the power generator 300 is equal to or greater than a predetermined reference power (first power generation condition), and is not met if neither is met. The mobile terminal 500 may also determine whether the first display condition is met based on information from the EMS 400 (for example, grid information and weather information).

[0055] When the first display condition is met (YES in S61), the mobile terminal 500 displays the first screen Sc1 as a pop-up in S62. The first screen Sc1 includes information D1 containing a message prompting the user to perform maintenance, and a maintenance execution button B1. Information D1 further includes the status of the power grid PG (operating status, etc.) and the status of the power generator 300 (power generation, etc.). The first screen Sc1 accepts the input of a shutdown request. The user can input a shutdown request to the mobile terminal 500 by operating the maintenance execution button B1 (for example, by pressing it).

[0056] In the following step S63, the mobile terminal 500 determines whether or not a shutdown request has been input by the user. In this embodiment, if the user operates the maintenance execution button B1, S63 determines that it is YES, and the process proceeds to S64. In S64, the mobile terminal 500 transmits the aforementioned maintenance execution request signal (see S11 in Figure 2) to the control unit 122. After that, the process returns to the first step (S61). On the other hand, if the user does not operate the maintenance execution button B1, S63 determines that it is NO, and the process returns to the first step (S61) without transmitting the maintenance execution request signal.

[0057] Figure 4 is a flowchart showing the second display control performed by the mobile terminal 500. Referring to Figure 4 along with Figure 1, in S71, the mobile terminal 500 determines whether a predetermined second display condition is met. The second display condition in this embodiment is met when both of the following conditions are met: the time period during which a power outage in the power grid PG is predicted to occur arrives within a predetermined time from the current time (second grid connection requirement), and the time period during which the power supplied from the power generator 300 to the PCS 120 is predicted to fall below a predetermined reference power arrives within the predetermined time from the current time (second power generation requirement). If either of these conditions is not met, the condition is not met. The predetermined reference power may be power sufficient to maintain the control device 250 in operation. The mobile terminal 500 may determine whether each of the second grid connection requirement and the second power generation requirement is met based on information from the EMS 400 (for example, grid information and weather forecast information). The second display condition being met means that it is predicted that the control device 250 will not be supplied with the predetermined power from a power source other than the energy storage device 210 (power grid PG, power generation device 300).

[0058] If the second display condition is not met (NO in S71), the mobile terminal 500 displays the second screen Sc2 in S72. The second screen Sc2 includes information D2 indicating that maintenance is being performed. Information D2 further includes the progress of the maintenance and the scheduled time for maintenance completion. The second screen Sc2 does not accept connection requests. As long as the second display condition is not met (NO in S71), the processes in S71 and S72 are repeated.

[0059] If the second display condition is met (YES in S71), the mobile terminal 500 displays the third screen Sc3 in S73. The third screen Sc3 further includes information D3 prompting the cancellation of maintenance and a maintenance cancellation button B2, in addition to information D2. The third screen Sc3 accepts the input of a connection request. The user can input a connection request to the mobile terminal 500 by operating (for example, pressing) the maintenance cancellation button B2.

[0060] After processing in S73, the mobile terminal 500 determines in S74 whether or not a connection request has been input by the user. In this embodiment, if the user operates the maintenance cancellation button B2, S74 determines YES and the process proceeds to S75. In S75, the mobile terminal 500 transmits the aforementioned maintenance cancellation request signal (see S14 in Figure 2) to the control unit 122. After that, the process returns to the first step (S71). On the other hand, if the user does not operate the maintenance cancellation button B2, S74 determines NO and the process returns to the first step (S71) without transmitting the maintenance cancellation request signal.

[0061] As explained above, in the energy storage system according to this embodiment, even if the SMR220 is in an interrupted state, the control device 250 can receive power from at least one of the power grid PG and the power generator 300. However, the control device 250 cannot always receive power from these power sources. Therefore, in the above energy storage system, when a connection request is input to the portable terminal 500 (input device) while the SMR220 is in an interrupted state (YES in S74 of Figure 4), the control device 250 connects the SMR220 (S26 of Figure 2). If a connection request is input to the portable terminal 500 while cell voltage equalization (item 2) is being performed, the control device 250 stops the cell voltage equalization and then connects the SMR220. The user can check the status of the power grid PG and the power generator 300 and connect the SMR220 as needed. This prevents the control device 250 from losing power and becoming inoperable. Furthermore, the Human Machine Interface (HMI) is not limited to the mobile terminal 500; other terminals may also be used as HMIs (input devices, etc.). The HMI may also accept voice input from the user.

[0062] The tripping condition (S11) and the condition for generating a tripping release request (S14) in the process shown in Figure 2 can be changed as appropriate. For example, the control unit 122 may learn how the user uses the electrical load 150 based on weather information and demand power, and set the tripping condition (S11) to be met during the time when the electrical load 150 is not being used. The EMS 400 may determine whether maintenance can be performed based on system information and weather information, and when it is time for maintenance to be performed, the EMS 400 may transmit a predetermined first signal to the control unit 122. When the control unit 122 receives the first signal, the tripping condition (S11) may be met. The EMS 400 may also predict whether the power supplied to the circuit unit 121 (PCS 120) will be insufficient based on disaster prediction information and weather prediction information. When it is predicted that the power supplied to the circuit unit 121 will be insufficient, the EMS 400 may transmit a predetermined second signal to the control unit 122. When the control unit 122 receives the second signal, a tripping release request (S14) may be generated. Furthermore, a request to release the circuit breaker (S14) may be generated when the power generated by the power generation device 300 (solar power generation) is below a predetermined value.

[0063] Each of the first and second display conditions (Figures 3 and 4) can also be changed as appropriate. For example, the first display condition (S61 in Figure 3) may be met only when the power generated by the power generation device 300 (solar power generation) is equal to or greater than a predetermined value.

[0064] The display content of each of the first to third screens Sc1 to Sc3 (Figures 3 and 4) can also be changed as appropriate. The EMS400 may request a recommended maintenance timing and transmit the recommended maintenance timing to the mobile terminal 500. The mobile terminal 500 may then display the recommended maintenance timing (advice to the user) on the first screen Sc1 (Figure 3).

[0065] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0066] 100 Building, 111 DC / DC converter, 112 Control device, 120 PCS, 121 Circuit section, 122 Control section, 130 Distribution board, 150 Electrical load, 210 Energy storage device, 220 SMR, 250 Control device, 300 Power generator, 400 EMS, 500 Mobile terminal, PG Power system.

Claims

1. A stationary energy storage device that supplies power to an electrical load, A control device that receives power from the aforementioned energy storage device and other power sources, A relay is positioned between the energy storage device and the control device, and between the energy storage device and the electrical load, and not between the control device and the power supply. An input device that receives input from the user, A power storage system comprising, The energy storage device includes a battery pack comprising a plurality of cells electrically connected to each other, The control device is configured to equalize the cell voltages in the battery pack when the relay is in the tripped state. A power storage system in which, when a connection request is input to the input device while the cell voltage equalization is being performed, the control device stops the cell voltage equalization and then connects the relay.

2. A stationary energy storage device for supplying power to an electrical load, A control device that receives power from the aforementioned energy storage device and other power sources, A relay is positioned between the energy storage device and the control device, and between the energy storage device and the electrical load, and not between the control device and the power supply. An input device that receives input from the user, A power storage system comprising, The control device is configured such that when a connection request is input to the input device while the relay is in the disconnected state, the relay is set to the connected state. The input device is configured to accept the connection request input when predetermined conditions are met, and not to accept the connection request input when the predetermined conditions are not met. An energy storage system in which the predetermined condition is met when it is predicted that a predetermined amount of power will not be supplied from the power source to the control device.

3. The input device is mounted on a portable terminal that can be carried by the user. The energy storage system according to claim 2, wherein the mobile terminal displays a button to accept input of the connection request when the predetermined conditions are met.

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