Storage battery control apparatus and power storage system

Abstract

To improve responsiveness to charging and discharging instructions in a power storage system that has a plurality of power storage strings connected in parallel.SOLUTION: A string system controller SSC changes the charging and discharging power of a power storage system 1 as a whole from a current value to a target value by selectively executing one of: a standard slope control that individually calculates a string charging and discharging power instruction value in each predetermined period in accordance with a power storage system charging and discharging instruction value for each of string controllers SC1 to SCx, and individually transmits the string charging and discharging power instruction value in each predetermined period to each of the string controllers SC1 to SCx; and a shortest slope control that calculates a string charging and discharging power instruction value that is common to the plurality of string controllers SC1 to SCx in accordance with the power storage system charging and discharging instruction value, and transmits the common string charging and discharging power instruction value to the plurality of string controllers SC1 to SCx at the same time.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery control device and a power storage system. [Background technology]

[0002] There is known a power storage system in which a plurality of assembled batteries are connected in parallel to a power supply target and a power grid via a plurality of power conditioning systems (PCSs) (see, for example, Patent Document 1). The power storage system described in Patent Document 1 includes an energy management system (EMS), a plurality of battery management units (BMUs), a plurality of state of charge (SOC) sensors, and the like. The EMS transmits a power instruction value to one of the plurality of BMUs, a master BMU. The master BMU sets charge / discharge instruction values ​​for all assembled batteries, and transmits the set charge / discharge instruction values ​​to all slave BMUs. Each slave BMU controls the charge / discharge amount of each assembled battery based on the received charge / discharge instruction value and the SOC of the assembled battery estimated by SOC estimation.

[0003] Also, as a system for controlling the discharge of a storage string in which multiple storage batteries are connected in series, a system is known that bypasses a storage battery that cannot discharge the required current and discharges the other storage batteries (see, for example, Patent Document 2). Furthermore, as a system for controlling the charging of a storage string in which multiple storage batteries are connected in series, a system is known that bypasses a storage battery that cannot charge the input current and charges the other storage batteries (see, for example, Patent Document 3). The storage systems described in Patent Documents 2 and 3 include a first switch that connects or disconnects the storage batteries, and a second switch that connects or disconnects the bypass line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-167928 A [Patent Document 2] JP 2013-31247 A [Patent Document 3] JP 2013-31249 A Summary of the Invention [Problem to be solved by the invention]

[0005] If the battery pack of the energy storage system described in Patent Document 1 is used as the energy storage string of the systems described in Patent Documents 2 and 3, complex charge and discharge control is required, which results in a huge amount of communication between the control devices and long communication times. As a result, responsiveness to charge and discharge instructions from the upper system is sacrificed, making it difficult to control the power receiving point, which requires a high-speed response.

[0006] In view of the above circumstances, an object of the present invention is to provide a storage battery control device and a storage system in which a plurality of storage strings are connected in parallel, which can improve responsiveness to charge / discharge instructions. [Means for solving the problem]

[0007] The battery control device of the present invention is a battery control device for controlling a battery system including a plurality of battery storage strings connected in parallel, the battery control device including: a plurality of first control units provided for each of the battery storage strings, and controlling charge / discharge power of the corresponding battery storage string; and a second control unit that receives a first charge / discharge power instruction value which is an instruction value for charge / discharge power of the entire battery storage system from a higher-level control unit, calculates a second charge / discharge power instruction value which is an instruction value for charge / discharge power for each of the battery storage strings in accordance with the received first charge / discharge power instruction value, and transmits the calculated second charge / discharge power instruction value to the corresponding first control unit, and the second control unit individually controls the second charge / discharge power instruction value for each predetermined period for each of the first control units in accordance with the first charge / discharge power instruction value received from the higher-level control unit. and transmits the calculated second charge / discharge power instruction value individually to the first control unit at each predetermined period, or a second control, in which the second charge / discharge power instruction value common to the plurality of first control units is calculated in accordance with the first charge / discharge power instruction value received from the higher-level control unit, and the calculated common second charge / discharge power instruction value is transmitted simultaneously to the plurality of first control units, thereby changing the charge / discharge power of the entire power storage system from a current value to a target value, and after execution of the first control or the second control, the second charge / discharge power instruction value is calculated individually for each of the first control units, and the calculated second charge / discharge power instruction value is transmitted individually to the first control unit, thereby adjusting the charge / discharge power of the plurality of power storage strings.

[0008] The power storage system of the present invention is a power storage system including a plurality of power storage strings connected in parallel, and a storage battery control device that controls charge / discharge power of the plurality of power storage strings, wherein the storage battery control device includes a plurality of first control units provided for each of the power storage strings and controlling the charge / discharge power of the corresponding power storage string, and a second control unit that receives a first charge / discharge power instruction value that is an instruction value for charge / discharge power of the entire power storage system from a higher-level control unit, calculates a second charge / discharge power instruction value that is an instruction value for charge / discharge power for each of the power storage strings in accordance with the received first charge / discharge power instruction value, and transmits the calculated second charge / discharge power instruction value to the corresponding first control unit, and the second control unit controls the second charge / discharge power instruction value for each predetermined period in accordance with the first charge / discharge power instruction value received from the higher-level control unit. and a third control is executed to change the charge / discharge power of the entire energy storage system from a current value to a target value by selectively executing one of a first control in which an instruction value is calculated individually for each of the first control units and the calculated second charge / discharge power instruction value is transmitted individually to the first control unit at each predetermined period, and a second control in which the second charge / discharge power instruction value common to the plurality of first control units is calculated according to the first charge / discharge power instruction value received from the higher-level control unit and the calculated common second charge / discharge power instruction value is transmitted simultaneously to the plurality of first control units. After execution of the first control or the second control, the third control is executed to adjust the charge / discharge power of the plurality of energy storage strings by calculating the second charge / discharge power instruction value individually for each of the first control units and transmitting the calculated second charge / discharge power instruction value individually to the first control unit. Effect of the Invention

[0009] According to the present invention, in a power storage system in which a plurality of power storage strings are connected in parallel, it is possible to improve responsiveness to a charge / discharge instruction. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a circuit diagram showing a circuit configuration of a power storage system including a battery control device according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a block diagram showing a control configuration of the power storage system shown in FIG. [Diagram 3] FIG. 3 is a flowchart for explaining the processing of the string system controller shown in FIG. 1 and FIG. [Figure 4] FIG. 4 is a graph illustrating updating of the power storage system charge / discharge power instruction value and the string charge / discharge power instruction value of each string. [Diagram 5] FIG. 5 is a graph illustrating updating of the power storage system charge / discharge power instruction value and the string charge / discharge power instruction value of each string. [Figure 6] FIG. 6 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of standard slope control during the slope control period of the power storage system discharge power. [Figure 7] FIG. 7 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the shortest slope control during the slope control period of the power storage system discharge power. [Figure 8] FIG. 8 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the standard slope control of the string discharge power. [Figure 9] FIG. 9 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the shortest slope control during the slope control period of the power storage system discharge power. [Figure 10] FIG. 10 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the shortest slope control during the slope control period of the power storage system discharge power. [Figure 11] FIG. 11 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the shortest slope control during the slope control period of the power storage system discharge power. [Figure 12]FIG. 12 is a table showing the power storage system discharge power instruction value and the string discharge power instruction value of each string at the start point of the standard slope control of the string discharge power. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and the embodiments can be appropriately modified within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are appropriately applied within the scope of not causing any contradiction with the contents described below.

[0012] Fig. 1 is a circuit diagram showing the circuit configuration of a power storage system 1 including a battery control device 2 (see Fig. 2) according to one embodiment of the present invention. The power storage system 1 shown in this figure is a stationary power source, and includes a string system 10 and a power storage system controller PSC.

[0013] The power storage system controller PSC is the highest hierarchical control device in the power storage system 1, and communicates with the upper server 7 (see FIG. 2) and the string system controller SSC to control the power storage system auxiliary devices 3 (see FIG. 2). The power storage system controller PSC also includes a display / input device (not shown) such as a touch panel having a display function and an input function.

[0014] The string system 10 includes a plurality of strings St1 to Stx, a string bus 6, a string system controller SSC, and a plurality of string controllers SC1 to SCx. The string system controller SSC and the string controllers SC1 to SCx will be described later.

[0015] The multiple strings St1 to Stx are connected in parallel to each other and to an external system (not shown) via a string bus 6. Each of the strings St1 to Stx includes power converters PCS1 to PCSx, a string cutoff switch 11, multiple modules M1 to Mm, and multiple module controllers MC1 to MCm. The module controllers MC1 to MCm will be described later.

[0016] Each of the modules M1-Mm includes a storage battery B1-Bm, a bypass switch unit BSU1-BSUm, and a voltage sensor 12. In each of the strings St1-Stx, a plurality of storage batteries B1-Bm are connected in series, and a bypass switch unit BSU1-BSUm is provided for each of the storage batteries B1-Bm. Each of the strings St1-Stx also includes a current sensor 13, a voltage sensor 14, a fuse 15, the same number of temperature sensors (not shown) as the number of storage batteries B1-Bm, and the same number of cell voltage sensors (not shown) as the number of storage battery cells.

[0017] The storage batteries B1 to Bm are secondary batteries such as lithium ion batteries and lithium ion capacitors, and are charged by receiving power from an external system via the power converters PCS1 to PCSx, and the charged power is discharged via the power converters PCS1 to PCSx to supply power to the external system. Although not particularly limited, the storage batteries B1 to Bm in this embodiment are regenerated second-hand storage batteries, and there is a difference in the degree of deterioration of each of the storage batteries B1 to Bm. Note that the storage batteries B1 to Bm may be storage battery packs in which a plurality of storage battery modules are connected in series, or may be composed of a single storage battery cell.

[0018] Each of the bypass switch units BSU1 to BSUm includes a bypass line BL and switches S1 and S2. The bypass line BL is a power line that bypasses each of the storage batteries B1 to Bm. The switch S1 is provided on the bypass line BL. The switch S1 is, for example, a mechanical switch, a semiconductor switch, or a relay. The switch S2 is provided between the positive electrode of each of the storage batteries B1 to Bm and one end of the bypass line BL. The switch S2 is, for example, a mechanical switch, a semiconductor switch, or a relay.

[0019] The starting battery B1 and the ending battery Bm are connected to an external system via power converters PCS1-PCSx and a string bus 6. When the switch S1 is turned OFF and the switch S2 is turned ON in all of the bypass switch units BSU1-BSUm, all of the batteries B1-Bm are connected in series to the external system. On the other hand, when the switch S2 is turned OFF and the switch S1 is turned ON in any of the bypass switch units BSU1-BSUm, the battery B1-Bm corresponding to that bypass switch unit BSU1-BSUm is bypassed.

[0020] The power converters PCS1 to PCSx are bidirectional converters, and are connected to a string bus 6. Furthermore, the positive electrode of the starting storage battery B1 and the negative electrode of the terminal storage battery Bm are connected to each of the power converters PCS1 to PCSx.

[0021] When charging the strings St1-Stx, the power converters PCS1-PCSx convert the voltage input from the string bus 6 according to the string charging power instruction value and output the converted voltage to the multiple storage batteries B1-Bm. Here, the voltage on the side of the strings St1-Stx changes according to the bypass state of the storage batteries B1-Bm (the number of bypassed storage batteries B1-Bm) and the charging state of the storage batteries B1-Bm. Therefore, when charging the strings St1-Stx, the power converters PCS1-PCSx convert the voltage input from the string bus 6 to the voltage on the side of the strings St1-Stx and output the converted voltage to the multiple storage batteries B1-Bm.

[0022] When the strings St1 to Stx are discharged, the power converters PCS1 to PCSx convert the voltages input from the batteries B1 to Bm according to the string discharge power instruction value and output the converted voltage to the string bus 6. Here, the input voltage of the power converters PCS1 to PCSx during discharge varies according to the bypass state of the batteries B1 to Bm and the charge state of the batteries B1 to Bm. This causes variations in the input voltages of the power converters PCS1 to PCSx among the strings St1 to Stx during discharge. Therefore, when the strings St1 to Stx are discharged, the power converters PCS1 to PCSx convert the input voltage to a voltage that matches the other strings St1 to Stx and output the converted voltage to the string bus 6. When the current flowing through the string bus 6 is AC, the power converters PCS1 to PCSx are provided with a synchronization means for following changes in the instantaneous value.

[0023] Each string cutoff switch 11 is provided between each power converter PCS1 to PCSx and the string bus 6. The string cutoff switch 11 connects or disconnects the strings St1 to Stx to the string bus 6. In addition, each fuse 15 is a power fuse provided between each string cutoff switch 11 and the string bus 6.

[0024] The voltage sensor 12 is connected between the positive and negative terminals of each of the storage batteries B1-Bm, detects the terminal voltage of each of the storage batteries B1-Bm, and transmits a detection signal to each of the module controllers MC1-MCm. The current sensor 13 is provided on the power line PL of each of the strings St1-Stx, detects the charge / discharge current of each of the strings St1-Stx (hereinafter, string current), and transmits a detection signal to each of the string controllers SC1-SCx. The voltage sensor 14 is provided on the power line PL of each of the strings St1-Stx, detects the total voltage of each of the strings St1-Stx (hereinafter, string total voltage), and transmits a detection signal to each of the string controllers SC1-SCx.

[0025] A temperature sensor is provided in each of the batteries B1-Bm to detect the temperature of the batteries B1-Bm and transmit a detection signal to the module controllers MC1-MCm. A cell voltage sensor is provided in each of the batteries B1-Bm to detect the voltage of each battery cell and transmit a detection signal to the module controllers MC1-MCm.

[0026] Fig. 2 is a block diagram showing a control configuration of the power storage system 1 shown in Fig. 1. As shown in this figure, the power storage system 1 includes a storage battery control device 2. The storage battery control device 2 includes a plurality of first control devices 21 and a second control device 22. Each of the first control devices 21 includes string controllers SC1 to SCx and a plurality of module controllers MC1 to MCm. The second control device 22 includes a power storage system controller PSC and a string system controller SSC.

[0027] The power storage system controller PSC, the string system controller SSC, the string controllers SC1 to SCx, and the module controllers MC1 to MCm are provided for each hierarchical level. The power storage system controller PSC corresponds to the hierarchical level of the top power storage system 1. The string system controller SSC corresponds to the hierarchical level of the string system 10 which is next to the hierarchical level of the power storage system 1. The string controllers SC1 to SCx correspond to the hierarchical level of the strings St1 to Stx which is next to the hierarchical level of the string system 10. The module controllers MC1 to MCm correspond to the hierarchical level of the modules M1 to Mm (see FIG. 1) which is next to the hierarchical level of the strings St1 to Stx.

[0028] The power storage system controller PSC communicates with the upper server 7 and the string system controller SSC to control and manage the power storage system accessories 3. The upper server 7 is provided in an aggregator facility, or in a power receiving facility in a building, factory, etc. This upper server 7 calculates a charge / discharge power instruction value for the entire power storage system 1 (hereinafter, the power storage system charge / discharge power instruction value) according to the state of the power storage system 1 and the power demand on the demand side, and transmits it to the power storage system controller PSC.

[0029] The power storage system accessories 3 include a temperature sensor that detects the temperature of the installation environment of the power storage system 1, such as a container, and a fire extinguishing system (both not shown). If the detected value of the temperature sensor exceeds a threshold, the power storage system controller PSC determines that the temperature of the installation environment of the power storage system 1 is abnormal, and outputs an abnormality notification to the display input device. In addition, the power storage system controller PSC monitors the operating state of the fire extinguishing system.

[0030] The power storage system controller PSC receives information about the states of the strings St1 to Stx (hereinafter, string state information) and information about the state of the string system 10 (hereinafter, string system state information) from the string system controller SSC, and outputs it to the upper server 7 and the display input device.

[0031] The states of strings St1 to Stx include operating states such as charging, discharging, suspension, maintenance, etc., string current, total string voltage, SOC of strings St1 to Stx (hereinafter, string SOC), SOH (State of Health) of strings St1 to Stx (hereinafter, string SOH), and limit values ​​of charge / discharge power (or charge / discharge current) of strings St1 to Stx (hereinafter, string charge / discharge power limit values).

[0032] The state of the string system 10 may include the current of the string bus 6 (see FIG. 1) (hereinafter, string bus current), the voltage of the string bus 6 (hereinafter, string bus voltage), the SOC of the string system 10 (hereinafter, string system SOC), the SOH of the string system 10 (hereinafter, string system SOH), and the limit value of the charge / discharge power (or charge / discharge current) of the string system 10 (hereinafter, string system charge / discharge power limit value).

[0033] The power storage system controller PSC estimates the state of the power storage system 1 based on the string state information and the string system state information received from the string system controller SSC. Examples of the state of the power storage system 1 include an operating state such as charging, discharging, suspension, and maintenance, the SOC of the power storage system 1 (hereinafter, power storage system SOC), and the SOH of the power storage system 1 (hereinafter, power storage system SOH). The power storage system controller PSC outputs information on the estimated state of the power storage system 1 (hereinafter, power storage system state information) to a display input device as necessary. Note that in this embodiment in which there is a single string system 10, the string system SOC is equal to the power storage system SOC, and the string SOH is equal to the power storage system SOH.

[0034] The power storage system controller PSC transmits information required for the processing of the upper server 7 to the upper server 7. Examples of information required for the processing of the upper server 7 include the power storage system SOC, the power storage system SOH, and the string system charge / discharge power limit value. Here, the upper server 7 determines a charge / discharge instruction corresponding to the power storage system 1 based on the "information required for the processing of the upper server 7" received from the power storage system controller PSC, and transmits the charge / discharge instruction to the power storage system controller PSC. Examples of the charge / discharge instruction include, in addition to the power storage system charge / discharge power instruction value, control amounts such as a constant voltage (CV) mode, a constant current (CC) mode, and a constant power (CP) mode, and an operation method such as an independent operation or a grid-connected operation.

[0035] The power storage system controller PSC transmits various instruction information inputted by an operator or the like via the display input device to the string system controller SSC. Examples of various instruction information that can be inputted via the display input device include an instruction to execute a maintenance / stop mode (hereinafter, a maintenance / stop instruction), an instruction to forcibly execute charging / discharging, an instruction to forcibly execute state estimation, and the like.

[0036] The maintenance / stop instruction may be an instruction to forcibly operate the power storage system auxiliary device 3, the string system auxiliary device 4, and the string auxiliary device 5. By forcibly operating the power storage system auxiliary device 3, the string system auxiliary device 4, and the string auxiliary device 5, it becomes possible to check the operation of the power storage system auxiliary device 3, the string system auxiliary device 4, and the string auxiliary device 5.

[0037] An example of an instruction to forcibly perform charging / discharging is an instruction to specify a predetermined charging / discharging amount and forcibly perform charging / discharging in the power storage system 1. By specifying the predetermined charging / discharging amount and forcibly performing charging / discharging in the power storage system 1, it becomes possible to check whether the power storage system 1 can charge / discharge the specified predetermined charging / discharging amount.

[0038] An example of an instruction to forcibly execute state estimation is an instruction to specify a predetermined item of state estimation and forcibly execute state estimation in the power storage system 1. By specifying a predetermined item of state estimation and forcibly executing state estimation in the power storage system 1, it becomes possible to acquire an item of state estimation such as the string system SOH or the power storage system SOH at any time.

[0039] The string system controller SSC communicates with the power storage system controller PSC and the multiple string controllers SC1 to SCx, and controls and manages the string system auxiliaries 4. The string system auxiliaries 4 include a temperature sensor that detects the ambient temperature, a cooling device in the string system 10, a circuit breaker for the string bus 6, a current sensor that detects the string bus current, a voltage sensor that detects the string bus voltage, and the like (all of which are omitted from the drawing).

[0040] The string system controller SSC receives string state information from the string controllers SC1 to SCx. The states of the strings St1 to Stx include operating states such as charging, discharging, suspension, and maintenance, string currents, string total voltages, string SOCs, string SOHs, string charge / discharge power limit values, and states of the string system accessories 4. The states of the string system accessories 4 include string bus currents and string bus voltages.

[0041] The string system controller SSC estimates the state of the string system 10 based on the string state information received from the string controllers SC1 to SCx. Examples of the state of the string system 10 include a string bus current, a string bus voltage, a string system SOC, a string system SOH, and a string system charge / discharge power limit value. The state of the string system 10 may be estimated by the power storage system controller PSC. The power storage system controller PSC may receive string state information from the string system controller SSC to estimate the state of the string system 10, and estimate the state of the power storage system 1 based on the estimation result.

[0042] For example, if the detected values ​​of the temperature sensor, current sensor, or voltage sensor or the estimated value of the state of the string system 10 exceed a threshold range, the string system controller SSC determines whether or not there is an abnormality in the string system 10, and stops operation of the string system 10 or sends an abnormality notification to the storage system controller PSC.

[0043] The string system controller SSC transmits to the power storage system controller PSC information required for processing by the power storage system controller PSC among the information received from the string controllers SC1 to SCx and information estimated by itself. Examples of information required for processing by the power storage system controller PSC include the string system SOC, the string system SOH, and the string system charge / discharge power limit value.

[0044] Here, the power storage system controller PSC determines an instruction corresponding to the string system 10 based on "information required for processing by the power storage system controller PSC" received from the string system controller SSC, and transmits the instruction information to the string system controller SSC. Examples of the instruction include a charge / discharge instruction for the string system 10 in the charge / discharge mode, an instruction to individually control each part of the string system 10 in the maintenance mode (hereinafter referred to as an individual control instruction), and a state estimation instruction for the string system 10 in the state estimation mode. Examples of the charge / discharge instruction for the string system 10 in the charge / discharge mode include, in addition to string charge / discharge power instruction values ​​to be assigned to each string St1 to Stx, instructions for a slope control mode, a constant voltage (CV) mode, a constant current (CC) mode, and a constant power (CP) mode control amount, an operation method such as an independent operation / grid connection, etc., which will be described later. Examples of the individual control instruction for the string system 10 in the maintenance mode include an instruction to individually control the string system auxiliary devices 4 such as the power converters PCS1 to PCSx, a cooling device, and switches S1 and S2. The state estimation instructions to the string system 10 in the state estimation mode include instructions to execute predetermined control necessary to estimate the states of the strings St1 to Stx.

[0045] The string system controller SSC receives an instruction corresponding to the above-mentioned string system 10 from the power storage system controller PSC, and judges whether or not the operation state of the string system 10 needs to be updated by comparing the instruction received this time with the instruction received last time. If the operation state of the string system 10 needs to be updated, the string system controller SSC determines the operation mode of each of the strings St1 to Stx, permission for a bypass request from each of the string controllers SC1 to SCx (hereinafter, bypass permission), and a string charge / discharge power instruction value to be assigned to each of the strings St1 to Stx. Examples of the operation mode of each of the strings St1 to Stx include a charge / discharge mode, a state estimation mode, and a maintenance / stop mode.

[0046] Here, the string system controller SSC determines the operation mode, bypass permission, and string charge / discharge power instruction value of each string St1 to Stx based on the operation history from the past to the present of each string St1 to Stx. Examples of the determination of the operation mode, etc. based on the operation history from the past to the present include the following (1) to (4). (1) Whether or not to perform state estimation for each of the strings St1 to Stx is determined based on the implementation timing of state estimation for each of the strings St1 to Stx. (2) Based on whether or not and when an abnormality is determined for each of the strings St1 to Stx, it is determined whether to perform maintenance on each of the strings St1 to Stx or whether to charge and discharge each of the strings St1 to Stx. (3) Depending on the presence or absence of a bypass request from each of the string controllers SC1 to SCx, the string charge / discharge power instruction value of each of the strings St1 to Stx is determined. For example, the string charge / discharge power instruction value of the strings St1 to Stx corresponding to the string controllers SC1 to SCx that have transmitted the bypass request is determined to be 0. After the bypass control of the strings St1 to Stx is completed, the string charge / discharge power instruction value for the strings St1 to Stx is increased. (4) A string charge / discharge power instruction value for each of the strings St1 to Stx is determined based on the string SOC, string SOH, and string total voltage of each of the strings St1 to Stx.

[0047] The string controllers SC1 to SCx communicate with the string system controller SSC and multiple module controllers MC1 to MCm, and control and manage the string auxiliaries 5. The string auxiliaries 5 include power converters PCS1 to PCSx, a current sensor 13 that detects a string current, a voltage sensor 14 that detects a total string voltage, a string cutoff switch 11, and the like (all see FIG. 1).

[0048] The string controllers SC1 to SCx receive information on the state of each of the storage batteries B1 to Bm (hereinafter, storage battery state information) from the module controllers MC1 to MCm. The state of each of the storage batteries B1 to Bm includes the temperature, current, voltage, and cell voltage of the storage batteries B1 to Bm, and the state of the bypass switch units BSU1 to BSUm.

[0049] The string controllers SC1-SCx estimate the SOC, SOH, charge / discharge power limit value, etc. of the storage batteries B1-Bm based on the storage battery state information received from the module controllers MC1-MCm. The SOC, SOH, charge / discharge power limit value, etc. of the storage batteries B1-Bm may be estimated by the module controllers MC1-MCm. In this case, the module controllers MC1-MCm may transmit the estimation results to the string controllers SC1-SCx.

[0050] The string controllers SC1 to SCx estimate the states of the strings St1 to Stx based on the storage battery state information received from the module controllers MC1 to MCm. Examples of the states of the strings St1 to Stx include the string SOH, the string SOC, and the string charge / discharge power limit value. The estimation of the states of the strings St1 to Stx may be performed by the string system controller SSC. In this case, the string controllers SC1 to SCx may transmit the storage battery state information and the estimation result of the storage battery state to the string system controller SSC.

[0051] For example, when the detection values ​​of the current sensor 13 and the voltage sensor 14 and the estimated values ​​of the states of the strings St1 to Stx are outside the threshold ranges, the string controllers SC1 to SCx determine the presence or absence of an abnormality in the strings St1 to Stx. In this case, the string controllers SC1 to SCx stop the operation of the strings St1 to Stx and / or transmit an abnormality notification to the string system controller SSC.

[0052] The string controllers SC1 to SCx transmit to the string system controller SSC information required for processing of the string system controller SSC among the information received from the module controllers MC1 to MCm and the information estimated by themselves. The information required for processing of the string system controller SSC includes the temperature, current, voltage, SOC, SOH, charge / discharge power limit value, cell voltage, state of the bypass switch units BSU1 to BSUm, string SOC, string SOH, string charge / discharge power limit value, etc. of the storage batteries B1 to Bm.

[0053] Here, the string system controller SSC determines instructions corresponding to each of the strings St1 to Stx based on "information required for processing by the string system controller SSC" received from the string controllers SC1 to SCx, and transmits the instruction information to the string controllers SC1 to SCx. The instructions include charge / discharge instructions for each of the strings St1 to Stx in the charge / discharge mode, individual control instructions for each of the strings St1 to Stx in the maintenance mode, and state estimation instructions for each of the strings St1 to Stx in the state estimation mode. Items of the charge / discharge instructions for each of the strings St1 to Stx in the charge / discharge mode include, in addition to the string charge / discharge power instruction value, the control amount of the constant voltage mode, the constant current mode, and the constant power mode, and the operation method such as independent operation / grid connection. Items of the individual control instructions for each of the strings St1 to Stx in the maintenance mode include instructions to individually control the bypass switch units BSU1 to BSUm. Items of the state estimation instructions in the state estimation mode include, for example, charging / discharging at a constant current and recording the terminal voltage of the storage batteries B1 to Bm at that time.

[0054] The string controllers SC1 to SCx receive instruction information corresponding to each of the strings St1 to Stx from the string system controller SSC, and determine whether or not the bypass schedule of each of the strings St1 to Stx needs to be updated by comparing the instruction information received this time with the instruction information received last time. The bypass schedule of each of the strings St1 to Stx is a plan for bypassing the storage batteries B1 to Bm by the bypass switch units BSU1 to BSUm, and is determined based on a predetermined criterion. The string controllers SC1 to SCx determine whether or not switching from charging to discharging or from discharging to charging is performed in each of the strings St1 to Stx, and if the switching is performed, determine that the bypass schedule needs to be updated. If the bypass schedule needs to be updated, the string controllers SC1 to SCx determine the bypass schedule of the storage batteries B1 to Bm based on the storage battery state information received from the module controllers MC1 to MCm and the estimated state of each of the storage batteries B1 to Bm.

[0055] On the other hand, the string controllers SC1 to SCx determine whether or not control of the string charge / discharge power is necessary by comparing the current and previous battery state information received from the module controllers MC1 to MCm with the estimated results of the states of the batteries B1 to Bm. If control of the string charge / discharge power is necessary, the string controllers SC1 to SCx control the power converters PCS1 to PCSx.

[0056] The string controllers SC1 to SCx control the power converters PCS1 to PCSx in accordance with the string charge / discharge power instruction value received from the string system controller SSC.

[0057] When the string controllers SC1 to SCx receive a maintenance / stop command from the string system controller SSC, they analyze the received maintenance / stop command and determine the type of maintenance to be performed. The types of maintenance include individual control, self-diagnosis, and replacement of the storage batteries B1 to Bm (hereinafter, storage battery replacement).

[0058] The individual control may include control for individually turning on / off the string cutoff switch 11 and the cooling devices in the strings St1 to Stx. The self-diagnosis may include abnormality determination for determining abnormalities that are difficult to determine during operation in the state estimation mode or the charge / discharge mode. The abnormality determination may include performing special control on the string auxiliaries 5 such as the power converters PCS1 to PCSx and the bypass switch units BSU1 to BSUm, acquiring the responses thereof using various sensors, and determining the presence or absence of an abnormality. The battery replacement may include providing guidance for replacing the batteries B1 to Bm that have deteriorated or have failed. When replacing the batteries, a work guide is displayed on the display / input device of the power storage system controller PSC, and the power storage system 1 executes necessary control such as stopping the strings St1 to Stx that are the targets of battery replacement. The strings St1 to Stx that are not the targets of battery replacement may be operated in the charge / discharge mode. After the battery replacement is completed, the strings St1 to Stx that have had their batteries replaced are operated in a state estimation mode, and battery state information is transmitted from the module controllers MC1 to MCm to the string controllers SC1 to SCx. The strings St1 to Stx that are not the targets of the battery replacement may be operated in a charge / discharge mode.

[0059] When the string controllers SC1 to SCx receive a state estimation instruction from the string system controller SSC, they compare the currently received string charge / discharge power instruction value with the previously received string charge / discharge power instruction value and determine whether there has been a change. When there is a change in the string charge / discharge power instruction value between the previous time and the current time, the string controllers SC1 to SCx control the string auxiliary device 5 and the bypass switch units BSU1 to BSUm in a predetermined manner so that state estimation of the strings St1 to Stx is possible. An example of a method for controlling the string auxiliary device 5 when the state estimation mode is executed is to turn on the string cutoff switch 11 and perform constant current control of the power converters PCS1 to PCSx. Also, an example of a method for controlling the bypass switch units BSU1 to BSUm when the state estimation mode is executed is to sequentially bypass the storage batteries B1 to Bm that have become fully discharged during discharging.

[0060] The string controllers SC1 to SCx record the battery state information received from the module controllers MC1 to MCm. The string controllers SC1 to SCx also update parameters used in estimating the state as necessary based on the battery state information received from the module controllers MC1 to MCm. These parameters include the SOH of the batteries B1 to Bm, a map of charge / discharge limit values ​​of the batteries B1 to Bm, and SOC-OCV characteristics.

[0061] The module controllers MC1 to MCm communicate with the string controllers SC1 to SCx to control and manage the module auxiliaries (not shown). The module auxiliaries include bypass switch units BSU1 to BSUm and various sensors. The various sensors include a voltage sensor that detects the voltage of the storage batteries B1 to Bm, a current sensor that detects the current of the storage batteries B1 to Bm, a temperature sensor that detects the temperature of the storage batteries B1 to Bm, and a cell voltage sensor that detects the cell voltage.

[0062] The module controllers MC1 to MCm receive storage battery state information from a cell monitoring unit (not shown) or the like. Examples of the states of the storage batteries B1 to Bm include the total voltage of the storage batteries B1 to Bm, the temperature of the storage batteries B1 to Bm, and the cell voltage. The cell monitoring unit receives detection signals from various sensors, such as a module voltage sensor that detects the module voltage, a cell voltage sensor that detects the cell voltage, and a module temperature sensor that detects the module temperature. The cell monitoring unit may be configured as a standalone unit, or may be configured by utilizing a battery cell monitoring IC (Integrated Circuit) in the module controllers MC1 to MCm.

[0063] The module controllers MC1 to MCm receive battery state information from the above-mentioned cell monitoring units or various sensors of the batteries B1 to Bm, and estimate the states of the batteries B1 to Bm based on the received information. Examples of the estimated states of the batteries B1 to Bm include the SOC, SOH, and charge / discharge power limit values ​​of the batteries B1 to Bm. The states of the batteries B1 to Bm may be estimated by the string controllers SC1 to SCx.

[0064] For example, when detected values ​​of the voltage sensors, cell voltage sensors, and module temperature sensors or estimated values ​​of the states of the storage batteries B1-Bm are outside the threshold ranges, the module controllers MC1-MCm determine whether or not there is an abnormality in the storage batteries B1-Bm. Then, the module controllers MC1-MCm shut off the storage batteries B1-Bm determined to have an abnormality using the bypass switch units BSU1-BSUm, or transmit an abnormality notification to the string controllers SC1-SCx.

[0065] The module controllers MC1 to MCm transmit to the string controllers SC1 to SCx information required for processing by higher-level controllers such as the string controllers SC1 to SCx, among information received from the cell monitoring units or various sensors and information estimated by themselves. Information required for processing by the string controllers SC1 to SCx includes the temperature, current, voltage, SOC, SOH, charge / discharge power limit value, cell voltage, and state of the bypass switch units BSU1 to BSUm of the storage batteries B1 to Bm.

[0066] Here, the string controllers SC1-SCx determine instructions corresponding to the respective batteries B1-Bm based on "information required for processing by the string controllers SC1-SCx" received from the module controllers MC1-MCm, and transmit the instruction information to the module controllers MC1-MCm. The instructions include bypass control of the batteries B1-Bm by the bypass switch units BSU1-BSUm, cut-off control of the batteries B1-Bm by the bypass switch units BSU1-BSUm, etc.

[0067] If there is a change between the current and previous instruction information received from the string controllers SC1-SCx, the module controllers MC1-MCm control the bypass switch units BSU1-BSUm to execute the above-mentioned bypass control or shutoff control. If there is a change in the information received from the cell monitoring units or various sensors and the information estimated by the module controllers MC1-MCm, the module controllers MC1-MCm execute exceptional control as necessary that is not based on an instruction from a higher-level controller. The module controllers MC1-MCm also transmit an instruction to the cell monitoring units to execute cell balancing for the storage batteries B1-Bm.

[0068] Fig. 3 is a flowchart for explaining the processing of the string system controller SSC shown in Fig. 1 and Fig. 2. When the power storage system 1 is operated, the processing of step S1 is started, and while the power storage system 1 is operating, the processing of steps S2 to S16 is repeated.

[0069] In step S1, the string system controller SSC initializes various parameters. Next, in step S2, the string system controller SSC receives string state information from each of the string controllers SC1 to SCx.

[0070] Next, in step S3, the string system controller SSC receives string system accessory status information (string bus voltage, string bus current, etc.) from the string system accessory 4.

[0071] Next, in step S4, the string system controller SSC estimates the state of the string system 10 based on the string state information received in step S2 and the string system accessory state information received in step S3. Note that the estimation of the state of the string system 10 may be performed by the power storage system controller PSC, and the estimation result may be transmitted from the power storage system controller PSC to the string system controller SSC or the upper server 7.

[0072] Next, in step S5, the string system controller SSC analyzes the information received or estimated in steps S2 to S4 and determines whether or not there is an abnormality in the string system 10. The string system controller SSC determines whether or not there is an abnormality in the string system 10, for example, by comparing various detection values ​​or estimated values ​​received or estimated in steps S2 to S4 with threshold values.

[0073] Next, in step S6, the string system controller SSC transmits information (string system state information) required for processing by the power storage system controller PSC and the upper server 7, among the information received, estimated, or determined in steps S2 to S5, to the power storage system controller PSC. Next, in step S7, the string system controller SSC receives an instruction transmitted from the power storage system controller PSC. Here, the power storage system controller PSC determines an instruction corresponding to the string system 10 (such as a power storage system charge / discharge power instruction value in a charge / discharge mode) based on the information received from the string system controller SSC in step S6, and transmits it to the string system controller SSC in step S7.

[0074] Next, in step S8, the string system controller SSC compares the current instruction with the previous instruction received from the power storage system controller PSC, and determines whether or not the operating states of the strings St1 to Stx need to be updated. For example, if there is a change between the previous and current storage system charge / discharge power instruction value received from the power storage system controller PSC, the string system controller SSC determines that the operating states of the strings St1 to Stx need to be updated. Also, for example, if there is a change between the previous and current individual control instruction in the maintenance mode received from the power storage system controller PSC, the string system controller SSC determines that the operating states of the strings St1 to Stx need to be updated. If a positive determination is made in step S8, the process proceeds to step S9, and if a negative determination is made in step S8, the process proceeds to step S2.

[0075] Next, in step S9, the string system controller SSC determines instructions for each of the string controllers SC1 to SCx in accordance with a predetermined condition. The predetermined conditions include the state of each of the strings St1 to Stx acquired in step S2, the operation history of each of the strings St1 to Stx from the past to the present, and various instructions inputted through the display input device. Items of instructions for each of the string controllers SC1 to SCx include the operation mode of each of the strings St1 to Stx (state estimation mode, charge / discharge mode, maintenance / stop mode, etc.), permission / non-permission of a bypass request from each of the string controllers SC1 to SCx, and allocation of string charge / discharge power instruction values ​​to each of the strings St1 to Stx. When a maintenance / stop instruction is inputted through the display input device, the string system controller SSC determines the instruction for each of the strings St1 to Stx to be a maintenance / stop instruction. Similarly, when an instruction to forcibly execute charging / discharging or state estimation is input via the display / input device of the power storage system controller PSC, the string system controller SSC determines the instruction for each of the strings St1 to Stx to be a charging / discharging instruction or a state estimation instruction.

[0076] Next, in step S10, the string system controller SSC sets a count value m for managing the transmission of instruction information to the string controllers SC1 to SCx to an initial value (m=1). Next, in step S11, the string system controller SSC determines whether the operation mode of the strings St1 to Stx to which the instruction is applied is a charge / discharge mode, a state estimation mode, or a maintenance / stop mode. If it is the charge / discharge mode, the process proceeds to step S13; if it is the state estimation mode, the process proceeds to step S12; and if it is the maintenance / stop mode, the process proceeds to step S14.

[0077] In step S12, the string system controller SSC transmits a state estimation instruction to the target string controllers SC1 to SCx. Items of the state estimation instruction include ON of a state estimation mode flag, a string charge / discharge power instruction value, bypass permission / non-permission, etc. In the state estimation mode of each of the strings St1 to Stx, for example, discharge is performed at a constant current, and data such as voltage is acquired during the discharge. Here, if there is variation in the deterioration degree of the storage batteries B1 to Bm in each of the strings St1 to Stx, the storage batteries B1 to Bm are fully discharged in order from the most deteriorated one. Then, each time the storage batteries B1 to Bm are fully discharged, a bypass request is transmitted from the module controllers MC1 to MCm. As a result, the string system controller SSC determines whether or not to notify bypass permission in response to the received bypass request, and transmits a notification of bypass permission / non-permission to the string controllers SC1 to SCx.

[0078] On the other hand, in step S13, the string system controller SSC transmits a charge / discharge instruction to the target string controllers SC1 to SCx. Items of the charge / discharge instruction include ON of the charge / discharge mode flag, a string charge / discharge power instruction value, bypass permission / non-permission, etc. If there is a fully discharged or fully charged storage battery B1 to Bm, a bypass request is transmitted from the module controllers MC1 to MCm. In response to the received bypass request, the string system controller SSC determines whether or not to notify bypass permission, and transmits a notification of bypass permission / non-permission to the string controllers SC1 to SCx.

[0079] On the other hand, in step S14, the string system controller SSC transmits a maintenance / stop instruction to the target string controllers SC1 to SCx. Items of the maintenance / stop instruction include ON of the maintenance / stop flag, various instructions, bypass permission / non-permission, etc. The various instructions are instructions corresponding to instructions inputted through the display input device. For example, an instruction to forcibly operate the power storage system auxiliary 3, the string system auxiliary 4, the string auxiliary 5, and the bypass switch units BSU1 to BSUm is included. Here, when an instruction to forcibly operate the bypass switch units BSU1 to BSUm is inputted through the display input device, the string system controller SSC transmits an instruction to permit / non-permit bypass to the string controllers SC1 to SCx. Note that the maintenance / stop instruction is not limited to being inputted through the display input device, but may be transmitted when an abnormality occurs or periodically.

[0080] The process proceeds from steps S12, S13, and S14 to step S15, where the string system controller SSC adds 1 to a count value m for managing the transmission of instruction information to the string controllers SC1 to SCx. Next, in step S16, the string system controller SSC determines whether or not the transmission of instructions to all of the string controllers SC1 to SCx has been completed. Specifically, the string system controller SSC determines whether or not the count value m has reached the total number x of the string controllers SC1 to SCx. If a negative determination is made in step S16, the process proceeds to step S11, and steps S11 to S16 are repeated. On the other hand, if a positive determination is made in step S16, the process proceeds to step S2, and the processing of steps S2 to S16 is repeated while the power storage system 1 is in operation.

[0081] 4 and 5 are graphs for explaining the update of the power storage system charge / discharge power instruction value and the string charge / discharge power instruction value of each of the strings St1 to Stx. As shown in these graphs, the power storage system charge / discharge power instruction value is updated so as to change from a current value to a target value over a predetermined period (a slope control period of the power storage system charge / discharge power in the figures).

[0082] After the storage system charge / discharge power instruction value is updated, the storage system charge / discharge power instruction value is maintained, while the string charge / discharge power instruction value of each string St1 to Stx is updated. The string charge / discharge power instruction value of each string St1 to Stx is updated so as to gradually change to the target value over a predetermined period (slope control period of string charge / discharge power in the figure). The string charge / discharge power instruction value of each string St1 to Stx after the storage system charge / discharge power instruction value is updated for the purpose of adjusting the balance of charge / discharge power among the strings St1 to Stx.

[0083] The graph in Fig. 4 shows the relationship between the energy storage system charge / discharge power instruction value and the string charge / discharge power instruction values ​​of the strings St1 to Stx and time when control for suppressing the response speed of updating the energy storage system charge / discharge power instruction value (hereinafter, referred to as standard slope control) is executed. The standard slope control is executed for the purpose of suppressing abrupt changes in the energy storage system charge / discharge power when the energy storage system charge / discharge power instruction value is updated.

[0084] The graph in Fig. 5 shows the relationship between the charge / discharge power instruction value of the power storage system and the string charge / discharge power instruction values ​​of the strings St1 to Stx and time when control for increasing the response speed of updating the charge / discharge power instruction value of the power storage system (hereinafter, shortest slope control) is executed. The shortest slope control is executed for the purpose of high-speed response when updating the charge / discharge power instruction value of the power storage system.

[0085] As shown in the graph of Fig. 4, when the standard slope control is executed, the charge / discharge power instruction value of the energy storage system changes from the current value to the target value over a longer slope control period (e.g., 1.3 to 30 [sec]) compared to when the shortest slope control is executed. During this slope control period, the string charge power instruction value of each of the strings St1 to Stx is updated so as to gradually change from the current value to the target value.

[0086] Here, the power storage system charge / discharge power instruction value is the sum of the string charge / discharge power instruction values ​​of the strings St1 to Stx. Therefore, the string system controller SSC determines the string charge / discharge power instruction value of each string St1 to Stx so that the string charge / discharge power instruction value of each string St1 to Stx gradually changes from the current value to the target value, and the sum of the string charge / discharge power instruction values ​​of each string St1 to Stx gradually changes from the current value to the target value of the power storage system charge / discharge power instruction value.

[0087] The string system controller SSC determines a target value of the string charge / discharge power instruction value for each of the strings St1 to Stx before the start of a slope control period of the charge / discharge power of the power storage system. The string system controller SSC also calculates a change amount ΔP1 of the string charge / discharge power instruction value for each of the strings St1 to Stx for each predetermined period (for example, a period of several seconds). The change amount ΔP1 is a value obtained by equally dividing the difference between the current value and the target value of the string charge / discharge power instruction value of each of the strings St1 to Stx into n, and is determined by the resolution. n is a value obtained by dividing the time of the slope control period by the above-mentioned predetermined period.

[0088] The string system controller SSC calculates the string charge / discharge power instruction value of each string St1 to Stx at each of the predetermined cycles during the slope control period of the charge / discharge power of the energy storage system, and transmits the calculated string charge / discharge power instruction value to each of the string controllers SC1 to SCx by unicast communication. The string charge / discharge power instruction value is a value obtained by adding the above-mentioned change amount ΔP1 to an assumed current value (hereinafter, assumed current value).

[0089] After transmitting the string charge / discharge power instruction value to all the string controllers SC1 to SCx, the string system controller SSC transmits a flag for updating the control of the power converters PCS1 to PCSx (hereinafter, PCS control update flag) to all the string controllers SC1 to SCx by broadcast communication.

[0090] During execution of the standard slope control, when the storage system charge / discharge power instruction value converges to the target value, the string charge / discharge power instruction value of each of the strings St1 to Stx also converges to the target value. During the subsequent string charge / discharge power slope control period, the string charge / discharge power instruction value of each of the strings St1 to Stx gradually changes in order to adjust the balance of the string charge / discharge power of each of the strings St1 to Stx.

[0091] The string system controller SSC determines the target value of the string charge / discharge power instruction value of each string St1-Stx for the purpose of balancing the charge / discharge power of each string St1-Stx when the storage system charge / discharge power instruction value converges to the target value. In addition, at the same time, the string system controller SSC calculates the change amount ΔP2 of the string charge / discharge power instruction value for each string St1-Stx for each predetermined period (for example, a period of several seconds). The calculation method of the change amount ΔP2 is the same as the above-mentioned change amount ΔP1.

[0092] The string system controller SSC transmits the string charge / discharge power instruction value of each of the strings St1 to Stx to each of the string controllers SC1 to SCx by unicast communication at each of the predetermined cycles during the slope control period of the string charge / discharge power. The string charge / discharge power instruction value is a value obtained by adding the above-mentioned change amount ΔP2 to the assumed current value.

[0093] The string system controller SSC transmits the string charge / discharge power instruction value to all the string controllers SC1 to SCx by unicast communication, and then transmits a PCS control update flag to all the string controllers SC1 to SCx by broadcast communication.

[0094] As shown in the graph of Fig. 5, when the shortest slope control is executed, the battery system charge / discharge power instruction value changes from the current value to the target value over a shorter slope control period (e.g., 200 [msec] to 2 [sec]) than when the standard slope control is executed. During this slope control period, the string charge power instruction value of each string St1 to Stx is updated so as to change from the current value to the intermediate target value in one cycle.

[0095] After the storage system charge / discharge power instruction value is updated, the storage system charge / discharge power instruction value is maintained, while the string charge / discharge power instruction value of each string St1 to Stx is updated. The string charge / discharge power instruction value of each string St1 to Stx is updated so as to gradually change from an intermediate target value to a final target value over a slope control period of the string charge / discharge power.

[0096] Here, the power storage system charge / discharge power instruction value is the sum of the string charge / discharge power instruction values ​​of the strings St1 to Stx. Therefore, the string system controller SSC determines the string charge / discharge power instruction value of each string St1 to Stx such that the string charge / discharge power instruction value of each string St1 to Stx changes from the current value to the intermediate target value in one cycle, and the sum of the string charge / discharge power instruction values ​​of each string St1 to Stx changes from the current value to the target value in one cycle.

[0097] The string system controller SSC determines the intermediate target values ​​of the string charge / discharge power instruction values ​​of all strings St1 to Stx to be the same value before the start of the slope control period of the charge / discharge power of the energy storage system. The string system controller SSC transmits the intermediate target values ​​of the string charge / discharge power instruction values ​​to all string controllers SC1 to SCx by broadcast communication during the slope control period of the charge / discharge power of the energy storage system. After that, the string system controller SSC transmits a PCS control update flag to all string controllers SC1 to SCx by broadcast communication.

[0098] Each string controller SC1-SCx controls each power converter PCS1-PCSx according to the received intermediate target value of the string charge / discharge power instruction value, and updates the charge / discharge power. Here, for the strings St1-Stx whose intermediate target value of the string charge / discharge power instruction value exceeds the charge / discharge power upper limit value, the corresponding string controller SC1-SCx limits the charge / discharge power to less than the intermediate target value and to the charge / discharge power upper limit value or less. In this case, the total value of the charge / discharge power of each string St1-Stx is less than the target value of the charge / discharge power of the power storage system. Therefore, in this case, the string system controller SSC corrects the target value of the power storage system charge / discharge power instruction value so that the charge / discharge power of the entire power storage system 1 satisfies the request of the power storage system controller PSC. This point will be described in detail later.

[0099] When the shortest slope control is performed, the string charge / discharge power instruction value of each string St1 to Stx converges to an intermediate target value at the time when the energy storage system charge / discharge power instruction value converges to the target value. Since this intermediate target value is different from the final target value, the slope control of the string charge / discharge power is performed after the energy storage system charge / discharge power instruction value converges to the target value. During the slope control period of the string charge / discharge power, the string charge / discharge power instruction value of each string St1 to Stx gradually changes from the intermediate target value to the final target value for the purpose of balancing the string charge / discharge power of each string St1 to Stx.

[0100] The string system controller SSC determines a final target value of the charge / discharge power instruction value of each string St1-Stx for the purpose of balancing the charge / discharge power of each string St1-Stx when the storage system charge / discharge power instruction value converges to the target value. In addition, at the same time, the string system controller SSC calculates a change amount ΔP3 of the string charge / discharge power instruction value for each predetermined period (e.g., a period of several seconds) for each string St1-Stx. The change amount ΔP3 is a value obtained by equally dividing the difference between the intermediate target value and the final target value of the string charge / discharge power instruction value of each string St1-Stx into n, and is determined by the resolution.

[0101] The string system controller SSC transmits the string charge / discharge power instruction value of each string St1 to Stx to all string controllers SC1 to SCx by unicast communication at each predetermined cycle during the slope control period of the string charge / discharge power. This string charge / discharge power instruction value is a value obtained by adding the above-mentioned change amount ΔP3 to the assumed current value.

[0102] The string system controller SSC transmits the string charge / discharge power instruction value to all the string controllers SC1 to SCx by unicast communication, and then transmits a PCS control update flag to all the string controllers SC1 to SCx by broadcast communication.

[0103] 6 to 12 are tables for explaining a method for determining the power storage system charge / discharge power instruction value and the string charge / discharge power instruction value of each string St1 to St63 during a slope control period of the power storage system charge / discharge power or the string charge / discharge power. The tables in FIG. 6 to FIG. 12 show the discharge power instruction value of the power storage system 1 as a whole (hereinafter, the power storage system discharge power instruction value) and the discharge power instruction value of each string St1 to St63 (hereinafter, the string discharge power instruction value). Hereinafter, a method for determining the power storage system discharge power instruction value and the string discharge power instruction value of each string St1 to Stx during a slope control period of the discharge power of the power storage system 1 as a whole (hereinafter, the power storage system discharge power) or the discharge power of each string St1 to St63 (string discharge power) will be explained. Note that a method for determining the charge power instruction value of the power storage system 1 as a whole and the charge power instruction value of each string St1 to Stx during a slope control period of the charge power of the power storage system 1 as a whole will not be explained, but is the same as the following explanation.

[0104] The table in Fig. 6 shows the energy storage system discharge power instruction value and the string discharge power instruction values ​​of each of the strings St1 to St63 at the start of the standard slope control of the slope control period of the energy storage system discharge power. As shown in this table, at the start of the standard slope control of the slope control period of the energy storage system discharge power, the string system controller SSC determines the string discharge power instruction values ​​of each of the strings St1 to St63 from "instruction 0" to "instruction n".

[0105] The string system controller SSC calculates the amount of change ΔP1 by dividing the difference between the "expected current value" and the value in the "command n" column by n equal parts, and calculates the values ​​of the columns from "command 1" to "command n". The value in the "command 1" column is the value obtained by adding the amount of change ΔP1 to the "expected current value", the value in the "command 2" column is the value obtained by adding the amount of change ΔP1 to the value in the "command 1" column, the value in the "command n-1" column is the value obtained by adding the amount of change ΔP1 to the value in the "command n-2" column, and the value in the "command n" column is the value in the "command target value" column. The "expected current value" is a value that the string system controller SSC expects based on the string discharge command value that it has sent and the discharge upper limit value of each of the strings St1 to St63.

[0106] The string system controller SSC transmits the value in the column of "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication. After that, the string system controller SSC repeatedly executes the following processes (1) to (4) at predetermined intervals.

[0107] (1) The string system controller SSC assigns the values ​​of the columns from "Instruction 1" to "Instruction target value" to the column to the left. That is, the string system controller SSC assigns the value of the column "Instruction 1" to the column "Instruction 0", assigns the value of the column "Instruction 2" to the column "Instruction 1", and assigns the value of "Instruction target value" to "Instruction n".

[0108] (2) When the energy storage system discharge power instruction value is updated, the string system controller SSC changes the "instruction target value" according to the updated energy storage system discharge power value, and updates the values ​​in the columns "Instruction 1" to "Instruction n" according to the changed "instruction target value." At this time, the string system controller SSC calculates the amount of change ΔP1 by equally dividing the difference between the "assumed current value" and the value in the column "Instruction n" by n, and calculates the values ​​in the columns from "Instruction 1" to "Instruction n."

[0109] (3) The string system controller SSC transmits the value in the column "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication.

[0110] (4) The string system controller SSC broadcasts a PCS control update flag to all the string controllers SC1 to SC63.

[0111] The table in FIG. 7 shows the storage system discharge power instruction value and the string discharge power instruction value of each string St1 to St63 at the start of the shortest slope control of the slope control period of the storage system discharge power. As shown in this table, at the start of the shortest slope control of the slope control period of the storage system discharge power, the string system controller SSC determines the string discharge power instruction values ​​of each string St1 to St63 for "instruction 0" and "instruction 1". The value in the column "instruction 0" is the value in the column "assumed current value", and the value in the column "instruction 1" is the value in the column "instruction target value". Moreover, the value in the column "instruction target value" is the value obtained by dividing the storage system discharge power instruction value by the number of dischargeable strings St1 to St63.

[0112] The string system controller SSC transmits the value in the column of "Command 0" as the string discharge power command value to all the string controllers SC1 to SC63 by broadcast communication. After that, the string system controller SSC executes the following processes (1) to (4).

[0113] (1) The string system controller SSC assigns the values ​​of the columns from "Instruction 1" to "Instruction target value" to the column to the left. That is, the string system controller SSC assigns the value of the column "Instruction 1" to the column "Instruction 0", and assigns the value of the column "Instruction target value" to the column "Instruction 1". If a column for "Instruction 2" exists, the value of the column "Instruction 2" is assigned to the column "Instruction 1", and the value of the "Instruction target value" is assigned to the column "Instruction 2".

[0114] (2) The string system controller SSC transmits the value in the column of "instruction 0" as the string discharge power instruction value to all the string controllers SC1 to SC63 by broadcast communication. Note that the string discharge power instruction value is not transmitted to the string controllers SC1 to SC63 corresponding to the strings St1 to St63 that do not perform the discharge operation. Furthermore, if the energy storage system discharge power instruction value is updated during execution of the shortest slope control of the energy storage system discharge power, the string system controller SSC transmits the string discharge power instruction value to the string controllers SC1 to SC63 by broadcast communication based on the energy storage system discharge power instruction value before the update, and then executes processing according to the energy storage system discharge power instruction value after the update. Here, the string system controller SSC may suspend processing according to the energy storage system discharge power instruction value before the update, and execute processing according to the energy storage system discharge power instruction value after the update.

[0115] (3) The string system controller SSC transmits a PCS control update flag to all the string controllers SC1 to SC63 by broadcast communication. Note that the transmission of the PCS control update flag to the string controllers SC1 to SC63 corresponding to the strings St1 to St63 that do not perform a discharge operation is not executed.

[0116] (4) The string system controller SSC executes the standard slope control of the string discharge power shown in the table of FIG. 8, and adjusts the balance of the string discharge power of each of the strings St1 to St63 while maintaining the discharge power of the power storage system.

[0117] The table in Fig. 8 shows the storage system discharge power instruction value and the string discharge power instruction value of each of the strings St1 to St63 at the start of the standard slope control of the string discharge power. As shown in this table, at the start of the standard slope control of the string discharge power slope control period, the string system controller SSC determines the string discharge power instruction value of each of the strings St1 to St63 from "instruction 0" to "instruction n".

[0118] The string system controller SSC calculates the amount of change ΔP3 by dividing the difference between the "estimated current value" and the value in the "command n" column by n, and calculates the values ​​in the columns from "command 1" to "command n". The value in the "command 1" column is the value obtained by adding the amount of change ΔP3 to the "estimated current value", the value in the "command 2" column is the value obtained by adding the amount of change ΔP3 to the value in the "command 1" column, the value in the "command n-1" column is the value obtained by adding the amount of change ΔP3 to the value in the "command n-2" column, and the value in the "command n" column is the value in the "command target value" column. The "estimated current value" is a value that the string system controller SSC assumes based on the string discharge command value (the value in the "command target value" column in the table of FIG. 7) transmitted by itself and the string discharge upper limit value of each string St1 to St63.

[0119] The string system controller SSC transmits the value in the column of "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication. After that, the string system controller SSC repeatedly executes the following processes (1) to (4) at predetermined intervals.

[0120] (1) The string system controller SSC assigns the values ​​of the columns from "Instruction 1" to "Instruction target value" to the column to the left. That is, the string system controller SSC assigns the value of the column "Instruction 1" to the column "Instruction 0", assigns the value of the column "Instruction 2" to the column "Instruction 1", and assigns the value of "Instruction target value" to "Instruction n".

[0121] (2) When the energy storage system discharge power instruction value is updated, the string system controller SSC transitions from the standard slope control of the string discharge power to the shortest slope control of the energy storage system discharge power.

[0122] (3) The string system controller SSC transmits the value in the column "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication.

[0123] (4) The string system controller SSC broadcasts a PCS control update flag to all the string controllers SC1 to SC63.

[0124] The tables in Figures 9 to 11 show the energy storage system discharge power command value and the string discharge power command values ​​of each of the strings St1 to St63 at the start of the shortest slope control of the slope control period of the energy storage system discharge power. Here, in the example shown in the tables in Figures 9 to 11, there are strings St2 and St3 whose "discharge power upper limit value" is lower than the "command target value."

[0125] As shown in the table of Fig. 9, at the start of the shortest slope control of the slope control period of the energy storage system discharge power, the string system controller SSC determines the string discharge power instruction value of each of the strings St1 to St63 for "instruction 0" and "instruction 1". The value in the "instruction 0" column is the value in the "assumed current value" column, and the value in the "instruction 1" column is the value in the "instruction target value" column. The value in the "instruction target value" column is the value obtained by dividing the energy storage system discharge power instruction value by the number of dischargeable strings St1 to St63.

[0126] The string system controller SSC compares the value in the column of "command target value", the value in the column of "command 1", and the value in the column of "discharge power upper limit value", and calculates the shortage or excess of the string discharge power that can be outputted by each of the strings St1 to St63 with respect to the value in the column of "command target value". Here, when the value in the column of "command target value" is smaller than the value in the column of "discharge power upper limit value" ("command target value" < "discharge power upper limit value"), the excess of the string discharge power that can be outputted by each of the strings St1 to St63 is 0 or more ("command 1" - "command target value" ≧ 0). On the other hand, when the value in the column of "command target value" is equal to or larger than the value in the column of "discharge power upper limit value" ("command target value" ≧ "discharge power upper limit value"), the shortage of the string discharge power that can be outputted by each of the strings St1 to St63 is 0 or more ("command target value" - "command 1" ≧ 0).

[0127] As shown in the tables of Fig. 10 and Fig. 11, the string system controller SSC corrects the storage system discharge power instruction value, and corrects the value in the column "Instruction 1" of the string discharge power instruction value of each string St1 to St63 according to the correction of the storage system discharge power instruction value. That is, the string system controller SSC corrects the storage system discharge power instruction value so that the total value (-1300 in Fig. 9, -120 in Fig. 10) of the shortage and excess of the string discharge power of each string St1 to St63 approaches 0. In addition, the string system controller SSC divides the corrected storage system discharge power instruction value by the number of dischargeable strings St1 to St63 to calculate the value in the column "Instruction 1", and substitutes the calculated value into the column "Instruction 1". The above process is repeated a necessary number of times until the total value of the shortage and excess of the string discharge power of each string St1 to St63 becomes 0.

[0128] The string system controller SSC transmits the value in the column of "Command 0" shown in the table of Fig. 11 as the string discharge power command value to all the string controllers SC1 to SC63 by broadcast communication. After that, the string system controller SSC executes the following processes (1) to (4).

[0129] (1) The string system controller SSC assigns the values ​​of the columns from "Instruction 1" to "Instruction target value" to the column to the left. That is, the string system controller SSC assigns the value of the column "Instruction 1" to the column "Instruction 0". If a column for "Instruction 2" exists, the value of the column "Instruction 2" is assigned to the column for "Instruction 1", and the value of "Instruction target value" is assigned to the column for "Instruction 2".

[0130] (2) The string system controller SSC broadcasts the value in the column "Command 0" as the string discharge power command value to all the string controllers SC1 to SC63. Note that the string discharge power command value is not transmitted to the string controllers SC1 to SC63 corresponding to the strings St1 to St63 that do not perform the discharge operation.

[0131] (3) The string system controller SSC transmits a PCS control update flag to all string controllers SC1 to SC63 by broadcast communication. Note that the transmission of the PCS control update flag to the string controllers SC1 to SC63 corresponding to the strings St1 to St63 that do not perform a discharge operation is not executed. Here, for the strings St2 and St3 whose discharge power upper limit value is lower than the command target value, the corresponding string controllers SC2 and SC3 control the power converters PCS2 and PCS3 so that the string discharge power equal to or lower than the discharge power upper limit value is output.

[0132] (4) The string system controller SSC executes the standard slope control of the string discharge power shown in the table of FIG.

[0133] The table in FIG. 12 shows the power storage system discharge power instruction value and the string discharge power instruction value of each of the strings St1 to St63 at the start of the standard slope control of the string discharge power.

[0134] As shown in this table, at the start of the standard slope control of the string discharge power slope control period, the string system controller SSC determines string discharge power instruction values ​​of each of the strings St1 to St63 from "instruction 0" to "instruction n."

[0135] The string system controller SSC calculates the amount of change ΔP3 by dividing the difference between the "expected current value" and the value in the "command n" column by n equal parts, and calculates the values ​​in the columns from "command 1" to "command n". The value in the "command 1" column is the value obtained by adding the amount of change ΔP3 to the "expected current value", the value in the "command 2" column is the value obtained by adding the amount of change ΔP3 to the value in the "command 1" column, the value in the "command n-1" column is the value obtained by adding the amount of change ΔP3 to the value in the "command n-2" column, and the value in the "command n" column is the value in the "command target value" column. The "expected current value" is the lower of the value in the "command 1" column and the value in the "discharge power upper limit value" column shown in the table of FIG. 11.

[0136] The string system controller SSC transmits the value in the column of "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication. After that, the string system controller SSC repeatedly executes the following processes (1) to (4) at predetermined intervals while maintaining the discharge power of the power storage system.

[0137] (1) The string system controller SSC assigns the values ​​of the columns from "Instruction 1" to "Instruction target value" to the column to the left. That is, the string system controller SSC assigns the value of the column "Instruction 1" to the column "Instruction 0", assigns the value of the column "Instruction 2" to the column "Instruction 1", and assigns the value of "Instruction target value" to "Instruction n".

[0138] (2) When the energy storage system discharge power instruction value is updated, the string system controller SSC transitions from the standard slope control of the string discharge power to the shortest slope control of the energy storage system discharge power.

[0139] (3) The string system controller SSC transmits the value in the column "Command 0" as the string discharge power command value to each of the string controllers SC1 to SC63 by unicast communication.

[0140] (4) The string system controller SSC broadcasts a PCS control update flag to all the string controllers SC1 to SC63.

[0141] As described above, the storage battery control device 2 according to this embodiment includes a plurality of string controllers SC1-SCx provided for each of the strings St1-Stx, a power storage system controller PSC, and a string system controller SSC that communicates with the plurality of string controllers SC1-SCx. Each of the string controllers SC1-SCx controls the string charge / discharge power (second charge / discharge power instruction value) of the corresponding strings St1-Stx. The string system controller SSC receives a power storage system charge / discharge power instruction value (first charge / discharge power instruction value) from the power storage system controller PSC, calculates a string charge / discharge power instruction value for each of the strings St1-Stx according to the received power storage system charge / discharge power instruction value, and transmits the calculated string charge / discharge power instruction value to the corresponding string controller SC1-SCx.

[0142] Here, the string system controller SSC changes the charging / discharging power of the power storage system from a current value to a target value by selectively executing one of the standard slope control and the shortest slope control during a slope control period of the charging / discharging power of the power storage system. Then, the string system controller SSC adjusts the string charging / discharging power of the multiple strings St1 to Stx by executing the standard slope control during a slope control period of the string charging / discharging power after the execution of the standard slope control or the shortest slope control.

[0143] In the standard slope control during the slope control period of the charge / discharge power of the energy storage system, the string system controller SSC calculates a string charge / discharge power instruction value for each predetermined period individually for each of the string controllers SC1 to SCx according to the energy storage system charge / discharge power instruction value received from the energy storage system controller PSC. Then, the string system controller SSC transmits the calculated string charge / discharge power instruction value individually to each of the string controllers SC1 to SCx for each predetermined period. This makes it possible to gradually change the energy storage system charge / discharge power over an arbitrary period of time when updating the energy storage system charge / discharge power instruction value, thereby suppressing abrupt changes in the energy storage system charge / discharge power.

[0144] In addition, in the shortest slope control of the slope control period of the charge / discharge power of the energy storage system, the string system controller SSC calculates a string charge / discharge power instruction value common to the multiple string controllers SC1 to SCx according to the energy storage system charge / discharge power instruction value received from the energy storage system controller PSC. Then, the string system controller SSC transmits the calculated common string charge / discharge power instruction value to the multiple string controllers SC1 to SCx all at once. This can improve the responsiveness when updating the energy storage system charge / discharge power instruction value.

[0145] In addition, in the standard slope control during the slope control period of the charge / discharge power of the energy storage system, the string system controller SSC transmits the string charge / discharge power instruction value calculated for each of the string controllers SC1 to SCx individually to each of the string controllers SC1 to SCx at every predetermined period by unicast communication. This makes it possible to converge the string charge / discharge power of each of the strings St1 to Stx to a target value at the time of completion of the slope control of the charge / discharge power of the energy storage system.

[0146] On the other hand, in the shortest slope control of the slope control period of the charge / discharge power of the energy storage system, the string system controller SSC simultaneously transmits a string charge / discharge power instruction value common to the multiple string controllers SC1 to SCx to the multiple string controllers SC1 to SCx by broadcast communication. This makes it possible to complete the slope control of the charge / discharge power of the energy storage system in a shorter time than the standard slope control.

[0147] Furthermore, when the string system controller SSC receives an updated energy storage system charge / discharge power instruction value from the energy storage system controller PSC while executing the standard slope control of the string charge / discharge power after executing the shortest slope control of the energy storage system charge / discharge power, the string system controller SSC shifts from the standard slope control of the string charge / discharge power to the shortest slope control of the energy storage system charge / discharge power, thereby improving responsiveness to updates of the energy storage system charge / discharge power.

[0148] Furthermore, when executing the shortest slope control of the charge / discharge power of the energy storage system, the string system controller SSC calculates the difference between the upper limit value of the string charge / discharge power and the string charge / discharge power instruction value for each of the strings St1 to Stx, and corrects the energy storage system charge / discharge power instruction value so that the total value of the differences of the multiple strings St1 to Stx is reduced. Then, the string system controller SSC calculates a string charge / discharge power instruction value common to the multiple string controllers SC1 to SCx according to the corrected energy storage system charge / discharge power instruction value. Then, the string system controller SSC transmits the calculated common string charge / discharge power instruction value to the multiple string controllers SC1 to SCx all at once. As a result, even if there are strings St1 to Stx whose upper limit values ​​of the string charge / discharge power are lower than the string charge / discharge power instruction value, it is possible to suppress the string charge / discharge power of the strings St1 to Stx to the upper limit value or less, and to bring the actual charge / discharge power of the energy storage system close to the energy storage system charge / discharge power instruction value received from the energy storage system controller PSC. It is not essential to correct the power storage system charge / discharge power instruction value so as to reduce the total value of the differences among the strings St1 to Stx, and the string charge / discharge power instruction value may be corrected so as to reduce the total value of the differences among the strings St1 to Stx. In this case, the string charge / discharge power instruction value is a common value among the string controllers SC1 to SCx.

[0149] Here, the charge / discharge power upper limit value is an estimated value of the charge / discharge power that the strings St1 to Stx can charge / discharge, whereas the charge / discharge power that the strings St1 to Stx can actually charge / discharge may be equal to or greater than the estimated value. In this case, if a string charge / discharge power instruction value exceeding the estimated charge / discharge power upper limit value is transmitted from the string system controller SSC and the strings St1 to Stx perform charging / discharging according to the transmitted string charge / discharge power instruction value, an error occurs between the charge / discharge power of the energy storage system 1 and the energy storage system charge / discharge power instruction value. Therefore, when performing the shortest slope control of the energy storage system charge / discharge power, the string controllers SC1 to SCx control the charge / discharge power to be equal to or less than the charge / discharge power upper limit value of each of the strings St1 to Stx according to the string charge / discharge power instruction value transmitted from the string system controller SSC. This can reduce the error between the charge / discharge power of the energy storage system 1 and the energy storage system charge / discharge power instruction value.

[0150] Furthermore, in the standard slope control of the battery storage system charge / discharge power or the string system charge / discharge power, the string system charge / discharge power instruction value is set so as to gradually change from a current value to a target value for each predetermined period. This allows the battery storage system charge / discharge power to be gradually changed over any time when the battery storage system charge / discharge power instruction value is updated, thereby making it possible to suppress abrupt changes in the battery storage system charge / discharge power.

[0151] In addition, the string system controller SSC transmits a string charge / discharge power instruction value to the multiple string controllers SC1 to SCx in the standard slope control or the shortest slope control, and then transmits an instruction to execute control of the power converters PCS1 to PCSx to the multiple string controllers SC1 to SCx simultaneously by broadcast communication. This makes it possible to shorten the communication time of the control instruction of the power converters PCS1 to PCSx and improve the responsiveness to the update of the charge / discharge power of the energy storage system.

[0152] The present invention has been described above based on the above-mentioned embodiment, but the present invention is not limited to the above-mentioned embodiment, and modifications may be made without departing from the spirit of the present invention, and publicly known or well-known technologies may be combined as appropriate.

[0153] For example, in the above-described embodiment, the string system controller SSC transmits a string charge / discharge power instruction value to the string controllers SC1 to SCx. However, the power storage system controller PSC and the string system controller SSC may be integrated, and the integrated controller may transmit the string charge / discharge power instruction value to the string controllers SC1 to SCx. Also, one of the multiple string controllers SC1 to SCx may be a master controller and the others may be slave controllers, and the master controller may transmit the string charge / discharge power instruction value to the slave controller. [Explanation of symbols]

[0154] 1: Energy storage system 2: Battery control device PCS1: Power converter PCS2: Power converter PCS3: Power converter PCSx: Power converter PSC: Power storage system controller (higher-level control unit) SC1: String controller (first control section) SC2: String controller (first control section) SC3: String controller (first control section) SC63: String controller (first control section) SCx: String controller (first control section) SSC: String System Controller (Second control section) St1: String (energy storage string) St2: String (energy storage string) St3: String (energy storage string) St4: String (energy storage string) St5: String (energy storage string) St63: String (energy storage string) Stx: String (energy storage string)

Claims

1. A battery control device for controlling a battery storage system including a plurality of battery storage strings connected in parallel, A plurality of first control units provided for each of the power storage strings to control charging / discharging power of the corresponding power storage strings; a second control unit that receives a first charge / discharge power instruction value which is an instruction value of charge / discharge power of the entire power storage system from a higher-level control unit, calculates a second charge / discharge power instruction value which is an instruction value of charge / discharge power for each of the power storage strings in accordance with the received first charge / discharge power instruction value, and transmits the calculated second charge / discharge power instruction value to a corresponding first control unit; Equipped with The second control unit is a first control that calculates the second charge / discharge power instruction value for each predetermined period individually for each of the first control units according to the first charge / discharge power instruction value received from the higher-level control unit, and transmits the calculated second charge / discharge power instruction value to the first control unit individually for each predetermined period; a second control for calculating the second charge / discharge power instruction value common to the plurality of first control units in response to the first charge / discharge power instruction value received from the higher-level control unit, and simultaneously transmitting the calculated common second charge / discharge power instruction value to the plurality of first control units; By selectively executing one of the above, the charging and discharging power of the entire power storage system is changed from a current value to a target value, A battery control device that executes a third control to adjust the charge / discharge power of the multiple storage strings by calculating the second charge / discharge power instruction value individually for each first control unit after executing the first control or the second control, and transmitting the calculated second charge / discharge power instruction value individually to the first control unit.

2. 2. The battery control device according to claim 1, wherein the second control unit transmits the calculated second charge / discharge power instruction value to the first control unit by unicast communication at each of the predetermined periods when the first control and the third control are executed, and transmits the calculated common second charge / discharge power instruction value to the multiple first control units simultaneously by broadcast communication when the second control is executed.

3. The battery control device according to claim 1 or 2, wherein the second control unit executes the second control when the second control unit receives the updated first charge / discharge power instruction value from the higher-level control unit during execution of the third control after execution of the second control.

4. 3. The battery control device according to claim 1 or 2, wherein, when executing the second control, the second control unit calculates a difference between a charge / discharge power upper limit value and the second charge / discharge power instruction value for each of the power storage strings, calculates the second charge / discharge power instruction value common to the multiple first control units that reduces the total value of the differences for the multiple power storage strings, and transmits the calculated common second charge / discharge power instruction value to the multiple first control units simultaneously.

5. The battery control device according to claim 4, wherein the first control unit, when executing the second control, controls the charging / discharging power to be equal to or less than the charging / discharging power upper limit value for each of the power storage strings in accordance with the second charging / discharging power instruction value transmitted from the second control unit.

6. The battery control device according to claim 1 , wherein the second charge / discharge power instruction value calculated in the first control for each predetermined period gradually changes from a current value to a target value.

7. the power storage system includes a plurality of power converters provided for the respective power storage strings and controlled by the first control unit to convert charging / discharging power of the power storage strings; 3. The battery control device according to claim 1 or claim 2, wherein the second control unit transmits the second charge / discharge power instruction value to a plurality of the first control units in the first control, the second control, or the third control, and then transmits an instruction to execute control of the power converter to the plurality of the first control units simultaneously by broadcast communication.

8. A plurality of storage strings connected in parallel; a battery control device for controlling charging and discharging power of the plurality of battery strings; A power storage system comprising: The battery control device includes: A plurality of first control units provided for each of the power storage strings to control charging / discharging power of the corresponding power storage strings; a second control unit that receives a first charge / discharge power instruction value which is an instruction value for charge / discharge power of the entire power storage system from a higher-level control unit, calculates a second charge / discharge power instruction value which is an instruction value for charge / discharge power for each of the power storage strings in accordance with the received first charge / discharge power instruction value, and transmits the calculated second charge / discharge power instruction value to a corresponding first control unit; Equipped with The second control unit is a first control that calculates the second charge / discharge power instruction value for each predetermined period individually for each of the first control units according to the first charge / discharge power instruction value received from the higher-level control unit, and transmits the calculated second charge / discharge power instruction value to the first control unit individually for each predetermined period; a second control for calculating the second charge / discharge power instruction value common to the plurality of first control units in response to the first charge / discharge power instruction value received from the higher-level control unit, and simultaneously transmitting the calculated common second charge / discharge power instruction value to the plurality of first control units; By selectively executing one of the above, the charging and discharging power of the entire power storage system is changed from a current value to a target value, a power storage system that executes a third control to adjust the charging and discharging power of the plurality of power storage strings by calculating the second charging and discharging power instruction value individually for each first control unit after executing the first control or the second control, and transmitting the calculated second charging and discharging power instruction value individually to the first control unit.

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