Storage battery control device, electrical storage system and battery control method

Abstract

A storage battery control device (100) assigns the command values of power or current for charging or discharging to a plurality of storage battery strings (STR1 to STRm), controls bypass switching units (B1 to Bn), and controls power converters (PC1 to PCm). The storage battery control device (100) assigns the command values assigned to the storage battery strings (STR1 to STRm) subject to bypass control to one or more of the storage battery strings (STR1 to STRm) not subject to bypass control, prior to controlling the bypass switching units (B1 to Bn), and stops the power converters (PC1 to PCm) of the storage battery strings (STR1 to STRm) to be controlled by bypass.

Description

TECHNICAL FIELD

[0001] The present invention relates to a storage battery control device, an electric power storage system, and a storage battery control method. STATE OF THE ART

[0002] An electric power storage system is known comprising a plurality of storage battery strings connected in parallel to a DC busbar, and a plurality of converters each provided for a corresponding storage battery string (for example, see Patent Literature 1). In the electric power storage system described in Patent Literature 1, the output value of each storage battery string is controlled so that the voltage value of the DC busbar is maintained at a predetermined target voltage value. In the electric power storage system described in Patent Literature 1, the range of the output value that each storage battery string is to output is limited to prevent overcharging and over-discharging of the storage battery.

[0003] On the other hand, an electric power storage system is known that includes a plurality of storage batteries connected in series and a bypass circuit provided for each of the storage batteries and configured to switch the corresponding storage battery between a connection state and a bypass state (see, for example, Patent Literature 2). In the electric power storage system described in Patent Literature 2, a storage battery that cannot discharge a required current is bypassed, and the discharge is performed by another storage battery. CITATION LISTPATENT LITERATURE Patent Literature 1: JP 2014-79164 A Patent Literature 2: JP 2013-31247 A SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0004] An electric power storage system is considered in which the storage battery string described in Patent Literature 1 is provided with the bypass circuit described in Patent Literature 2. In this electric power storage system, when bypass control is performed for the storage battery string in the charging state, a sudden change in the charging and discharging power (or current) of the storage battery string occurs, and the charging and discharging power (or current) of the entire electric power storage system is affected. Here, the charging and discharging power (or current) of another storage battery string is changed to compensate for the sudden change in the charging and discharging power (or current) of the storage battery string to be subjected to bypass control, so that the charging and discharging power (or current) of the entire electric power storage system is not affected.However, it is difficult to fully synchronize the switching control of the bypass circuit of the storage battery string to be subjected to bypass control with the control of the charging and discharging power (or current) of the other storage battery string. Accordingly, there is a possibility that the target charging and discharging power (or current) of the electric power storage system cannot be maintained constant when bypass control is performed.

[0005] In view of the above circumstances, an object of the present invention is to provide a storage battery control device, an electric power storage system, and a storage battery control method that can maintain a target charge and discharge power (or current) of the electric power storage system when bypass control is performed in the electric power storage system in which a plurality of storage battery strings are connected in parallel and each storage battery string is provided with a bypass circuit. SOLUTION TO THE PROBLEM

[0006] A storage battery control device according to the present invention is a storage battery control device for controlling an electric power storage system comprising a plurality of storage battery strings connected in parallel to each other, the storage battery string including a plurality of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery string. The storage battery control device assigns a control value for the charging or discharging power or the charging current to the plurality of storage battery strings, controls the bypass circuit, and controls the power converter.The storage battery control device, before controlling the bypass circuit, assigns the control value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stops the power converter of the storage battery string to be controlled by the bypass circuit.

[0007] An electric power storage system according to the present invention is an electric power storage system including a plurality of storage battery strings connected in parallel to each other and a storage battery control device configured to control the storage battery strings. The storage battery string includes a plurality of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery string. The storage battery control device assigns a command value of the charge or discharge power or current to the plurality of storage battery strings, controls the bypass circuit, and controls the power converter.The storage battery control device, before controlling the bypass circuit, assigns the control value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stops the power converter of the storage battery string to be controlled by the bypass circuit.

[0008] A storage battery control method according to the present invention is a storage battery control method executed by a storage battery control device for controlling an electric power storage system including a plurality of storage battery strings connected in parallel to each other, the storage battery string including a plurality of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery string. The storage battery control method includes assigning an instruction value of the charge or discharge power or current of the plurality of storage battery strings, controlling the bypass circuit, and controlling the power converter.The storage battery control method includes, before controlling the bypass circuit, assigning the control value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stopping the converter of the storage battery string to be controlled by the bypass circuit. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0009] According to the present invention, in the electric power storage system in which a plurality of storage battery strings are connected in parallel and each storage battery string is provided with a bypass circuit, it is possible to maintain a target charge and discharge power (or current) of the electric power storage system when bypass control is performed. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. 1 is a circuit diagram schematically showing an electric power storage system including a storage battery control device according to an embodiment of the present invention. [ Fig. 2] Fig. 2 is a diagram showing the relationship between the instruction value of the charging power to be assigned to a storage battery string and the elapsed time when the instruction value of the charging power is changed. [ Fig. 3] Fig. 3 is a flowchart showing the processing for changing the instruction value of the charging power of the storage battery series. [ Fig. 4] Fig. 4 is a graph showing the relationship between the instruction value of the discharge power to be assigned to the storage battery series and the elapsed time when the instruction value of the discharge power changes. [ Fig. 5] Fig. 5 is a flowchart showing the process of changing the instruction value of the discharge power of the storage battery series. DESCRIPTION OF THE EMBODIMENTS

[0010] Hereinafter, the present invention will be described with reference to a preferred embodiment. The present invention is not limited to the embodiment to be described below, and the embodiment can be appropriately modified without departing from the gist of the present invention. In the embodiment to be described below, some configurations may not be described or illustrated in the drawings, and with respect to the details of the omitted techniques, publicly known or well-known techniques are appropriately applied as long as there is no contradiction with the contents to be described below.

[0011] Fig. 1 is a circuit diagram schematically showing an electric power storage system 1 including a storage battery control device 100 according to an embodiment of the present invention. As shown in this drawing, the electric power storage system 1 includes m sets (m is an integer of 2 or more) of storage battery strings STR1 to STRm, a series bus bar 3, and the storage battery control device 100. The m sets of storage battery strings STR1 to STRm are connected in parallel to each other and connected to an external system (not shown) via the series bus bar 3. The electric power storage system 1 is a stationary or in-vehicle power supply.

[0012] The battery storage strings STR1 to STRm each include n (n is an integer of 2 or more) storage battery modules M1 to Mn connected in series. Although not particularly limited, the storage battery strings STR1 to STRm according to the present embodiment are obtained by remanufacturing used storage batteries, and the storage battery modules M1 to Mn differ in the degree of deterioration. The storage battery modules M1 to Mn are formed by connecting a plurality of secondary cells, such as lithium-ion batteries and lithium-ion capacitors.

[0013] The storage battery modules M1 to Mn are charged with power supplied by the external system via series busbar 3 and the power converters PC1 to PCm, which will be described later. The storage battery modules M1 to Mn supply power to the external system via the power converters PC1 to PCm and series busbar 3.

[0014] The external system includes a load, a power generator, and the like. When the electrical power storage system 1 is a stationary power storage system, household appliances, commercial power systems, liquid crystal displays, communication modules, and the like serve as loads, and a photovoltaic power generation system or the like serves as a power generator. On the other hand, when the electrical power storage system 1 is an in-vehicle power storage system, a drive motor, an air conditioner, various in-vehicle electrical components, and the like serve as loads. The drive motor serves as both a load and a power generator.

[0015] Each of the storage battery strings STR1 to STRm may include n storage battery cells or storage battery packs connected in series, instead of the n storage battery modules M1 to Mn connected in series. The electrical power storage system 1 may include a bypass circuit that bypasses each storage battery cell or storage battery pack.

[0016] Each of the storage battery strings STR1 to STRm includes one of the power converters PC1 to PCm and n bypass switch units B1 to Bn. Each of the storage battery strings STR1 to STRm includes n voltage sensors 12, a current sensor 13, a voltage sensor 14, n temperature sensors (not shown), and a large number of cell voltage sensors (not shown).

[0017] The power converters PC1 to PCm are DC / DC converters or DC / AC converters and are connected to the series busbar 3. A positive electrode of the storage battery module M1 at the beginning and a negative electrode of the storage battery module Mn at the end are connected to each of the power converters PC1 to PCm.

[0018] When the storage battery strings STR1 to STRm are charged, each of the power converters PC1 to PCm converts a voltage received from the series bus bar 3 according to the command value of the charging power (or charging current) described later, and outputs the converted voltage to the plurality of storage battery modules M1 to Mn. Here, a voltage on a side of each of the storage battery strings STR1 to STRm changes due to a bypass state (the number of bypassed storage battery modules M1 to Mn) of the storage battery modules M1 to Mn and a charge state of the storage battery modules M1 to Mn. Therefore, when the storage battery strings STR1 to STRm are charged, each of the power converters PC1 to PCm converts the voltage received from the series bus bar 3 into the voltage on the side of each of the storage battery strings STR1 to STRm and outputs the converted voltage to the plurality of battery modules M1 to Mn.

[0019] When the storage battery strings STR1 to STRm are discharged, each of the power converters PC1 to PCm converts a voltage received from the plurality of storage battery modules M1 to Mn according to the instruction value of the discharge power (or current) described later, and outputs the converted voltage to the series bus bar 3. Here, the input voltage to each of the power converters PC1 to PCm changes during discharge due to a bypass state of the storage battery modules M1 to Mn and a charge state of the storage battery modules M1 to Mn. Accordingly, the input voltages to the power converters PC1 to PCm vary between the storage battery strings STR1 to STRm during discharge.When the battery storage strings STR1 to STRm are discharged, each of the power converters PC1 to PCm converts the input voltage into a voltage that is matched with the other storage battery strings STR1 to STRm and outputs the converted voltage to the string busbar 3.

[0020] When a current flowing through the series busbar 3 is a direct current, the power converters PC1 to PCm are DC / DC converters, and when the current flowing through the series busbar 3 is an alternating current, the power converters PC1 to PCm are DC / AC converters. When the current flowing through the series busbar 3 is an alternating current, each of the power converters PC1 to PCm is provided with a synchronization unit that follows a change in an instantaneous value.

[0021] The voltage sensor 12 is connected between the positive and negative electrode terminals of each of the storage battery modules M1 to Mn, detects a voltage between the terminals of each of the storage battery modules M1 to Mn, and transmits a detection signal to each of the series controllers C1 to Cm described later. The current sensor 13 is provided on a power line PL of each of the storage battery series STR1 to STRm, detects charging and discharging currents of each of the storage battery series STR1 to STRm, and transmits detection signals to each of the series controllers C1 to Cm. The voltage sensor 14 is provided on the power line PL of each of the storage battery series STR1 to STRm, detects the total voltage of each of the storage battery series STR1 to STRm, and transmits a detection signal to each of the series controllers C1 to Cm.

[0022] A temperature sensor is provided for each of the storage battery modules M1 to Mn, which detects the temperature of each of the storage battery modules M1 to Mn and sends a detection signal to each of the series controllers C1 to Cm. Furthermore, a cell voltage sensor is provided for each storage battery cell of each of the storage battery modules M1 to Mn, which detects a voltage of the storage battery cell and sends a detection signal to each of the series controllers C1 to Cm.

[0023] The bypass switch units B1 to Bn are provided for the storage battery modules M1 to Mn, respectively. Each of the bypass switch units B1 to Bn includes a bypass line BL and switches S1 and S2. The bypass line BL is a line that bypasses each of the storage battery modules M1 to Mn. The switch S1 is provided on the bypass line BL. The switch S1 is, for example, a mechanical relay or a semiconductor switch. The switch S2 is provided between a positive electrode of each of the storage battery modules M1 to Mn and one end of the bypass line BL. The switch S2 is, for example, a mechanical relay or a semiconductor switch.

[0024] The storage battery module M1 at the starting end and the storage battery module Mn at the end are connected to the external system via the power converters PC1 to PCm and the series busbar 3. When switch S1 is turned off and switch S2 is turned on in all bypass switch units B1 to Bn, all the series battery modules M1 to Mn are connected in series to the external system. On the other hand, when switch S2 is turned off and switch S1 is turned on in any of the bypass switch units B1 to Bn, the storage battery modules M1 to Mn corresponding to the bypass switch units B1 to Bn are bypassed.

[0025] The storage battery control device 100 includes m series controllers C1 to Cm and a system controller 101. The series controllers C1 to Cm are provided for the storage battery series STR1 to STRm, respectively.

[0026] The series controllers C1 to Cm control the switches S1 and S2 of the bypass switch units B1 to Bn of the corresponding storage battery series STR1 to STRm and the corresponding power converters PC1 to PCm. The power converters PC1 to PCm convert the charging and discharging voltages of the corresponding storage battery series STR1 to STRm under the control of the corresponding series controllers C1 to Cm.

[0027] The string controllers C1 to Cm detect states of the corresponding storage battery strings STR1 to STRm, estimate the states of the corresponding storage battery strings STR1 to STRm, and notify the system controller 101 of device control requests. Examples of detecting the states of the storage battery strings STR1 to STRm include detecting charging and discharging currents of the storage battery strings STR1 to STRm based on detection signals from the current sensors 13, detecting the total voltage of the storage battery strings STR1 to STRm based on detection signals from the voltage sensors 14, detecting voltages of the storage battery modules M1 to Mn based on detection signals from the voltage sensors 12, detecting temperatures of the storage battery modules M1 to Mn based on detection signals from the temperature sensors, and detecting voltages of the storage battery cells based on detection signals from the cell voltage sensors.Examples of estimating the states of the storage battery strings STR1 to STRm include estimating the states of charge (SOCs) and states of health (SOHs) of the storage battery modules M1 to Mn, and estimating the states of charge (SOCs) and states of health (SOHs) of the storage battery strings STR1 to STRm. Further, examples of notifications of the device control requests to the system controller 101 include notification of a request to turn on the switches S1 and S2 of the bypass switch units B1 to Bn, and notification of a request to control the power converters PC1 to PCm.

[0028] Examples of a method for estimating SOH include a method based on a charge and discharge test, a method based on a current integration method, a method based on an open-circuit voltage measurement, a method based on a terminal voltage measurement, a method based on a model (the above is a method using a temporal change in SOC), a method based on an AC impedance measurement, a method for obtaining using an adaptive digital filter based on a model, a method by linear regression (a slope of a straight line of IV characteristics) based on IV characteristics (current-voltage characteristics), and a method based on a step response (the above is a method for estimating using a temporal increase in internal resistance).

[0029] Examples of a state of charge estimation method include various known methods, such as a current integration method, a method (voltage measurement method) for obtaining based on an open-circuit voltage (OCV), and a method that combines the current integration method and the voltage measurement method. The OCV can be estimated using various known estimation methods using a temporal change in the terminal voltage or a temporal increase in the internal resistance.

[0030] Here, the series controllers C1 to Cm calculate the charging and discharging powers of the corresponding storage battery series STR1 to STRm and transmit the calculation results to the system controller 101. The charging and discharging powers of the storage battery series STR1 to STRm are calculated using the product of the charging and discharging currents of the storage battery series STR1 to STRm detected by the current sensors 13 of the storage battery series STR1 to STRm and the total voltage of the storage battery series STR1 to STRm detected by the voltage sensors 14 of the storage battery series STR1 to STRm.

[0031] The system controller 101 is a controller that integrally controls the entire electric power storage system 1 and performs 1:m communication with the m series controllers C1 to Cm. The system controller 101 monitors the states of the storage battery series STR1 to STRm, determines whether to allow device control requests from the series controllers C1 to Cm, and notifies the series controllers C1 to Cm of the approval of the device control requests. The system controller 101 sets the command values of the charging and discharging powers (or currents) of the storage battery series STR1 to STRm and transmits the command values of the charging and discharging powers (or currents) to the series controllers C1 to Cm.

[0032] The system controller 101 monitors the states of the storage battery strings STR1 to STRm based on the detection results and estimations of the states of the storage battery strings STR1 to STRm transmitted from the string controllers C1 to Cm. Then, the system controller 101 calculates the control value of the charging and discharging power (or charging current) to be assigned to each of the storage battery strings STR1 to STRm according to the instruction of the input and output power (or input and output current) of the entire electric power storage system 1 received from a higher-level system (not shown) and the states of the storage battery strings STR1 to STRm.

[0033] Here, the system controller 101 determines the priority order of the storage battery strings STR1 to STRm to which the charge and discharge power (or charge current or discharge current) instruction values are assigned according to the states of the monitored storage battery strings STR1 to STRm. Then, the system controller 101 assigns the charge and discharge power (or charge current or discharge current) instruction values to the storage battery strings STR1 to STRm according to the determined priority order. For example, the system controller 101 may assign the charge and discharge power (or charge current or discharge current) instruction values to the storage battery strings STR1 to STRm that have a relatively high priority, but may not assign the charge and discharge power (or charge current or discharge current) instruction values to the storage battery strings STR1 to STRm that have a relatively low priority.For example, the system controller 101 may assign a larger command value of the charge and discharge power (or current) to the storage battery strings STR1 to STRm that have a relatively high priority, and assign a smaller command value of the charge and discharge power (or current) to the storage battery strings STR1 to STRm that have a relatively low priority.

[0034] Examples of a method for determining the priority order include a method for determining the priority order according to the integrated charge and discharge capacity of each of the storage battery strings STR1 to STRm, a method for determining the priority order according to the SOH of each of the storage battery strings STR1 to STRm, and a method for randomly determining the priority order whenever the power (or current) of charging and discharging changes. In the method of determining the priority order according to the integrated charge and discharge capacity of each of the storage battery strings STR1 to STRm, the priority order is higher for the storage battery strings STR1 to STRm that have a lower integrated charge and discharge capacity.In the method of determining the priority order according to the SOH of each of the storage battery strings STR1 to STRm, the priority order is higher for the storage battery strings STR1 to STRm having a higher SOH of each of the storage battery strings STR1 to STRm.

[0035] The system controller 101 determines whether to respond to the device control requests from the series controllers C1 to Cm according to the monitored states of the other storage battery series STR1 to STRm. If the device control requests from the series controllers C1 to Cm are permitted, the system controller 101 transmits a notification of permission for the control requests to the series controllers C1 to Cm. The series controllers C1 to Cm that receive the notification of permission for the control requests for the bypass switch units B1 to Bn execute the switching control on the corresponding bypass switch units B1 to Bn. The series controllers C1 to Cm that receive the notification of permission for the control requests for the power converters PC1 to PCm control the corresponding power converters PC1 to PCm.

[0036] In a situation where the device control request is not transmitted from a specific one of the series controllers C1 to Cm, the system controller 101 can transmit a device control instruction to one of the series controllers C1 to Cm, if necessary. When the series controllers C1 to Cm detect an abnormality in the storage battery series STR1 to STRm, they can stop the operation of the power converters PC1 to PCm regardless of whether or not there is a control permission notification or a control instruction from the system controller 101.

[0037] When the system controller 101 receives a control request for the bypass switch units B1 to Bn from one of the series controllers C1 to Cm, the system controller 101 stops the operation of the power converters PC1 to PCm (hereinafter, PC') corresponding to the series controllers C1 to Cm (hereinafter, C'). The operation of the power converter PC' is stopped, so that the storage battery strings STR1 to STRm (hereinafter, STR') corresponding to the power converter PC' are in an unloaded state.

[0038] Then, the system controller 101 assigns the value "0" to the command value of the charge and discharge power (or charge current) of the storage battery string STR' in the unloaded state. On the other hand, the system controller 101 assigns a value to the command values of the charge and discharge power (or current) of one or more other storage battery strings STR1 to STRm that can supplement the charge and discharge power (or current) of the storage battery string STR' in the unloaded state.

[0039] At this time, in the process of changing the command values of the charge and discharge power (or current) of the storage battery strings STR', STR1 to STRm, the system controller 101 gradually and continuously changes the command value of the charge and discharge power (or current) of each of the storage battery strings STR', STR1 to STRm from the current value to the target value. That is, the system controller 101 gradually and continuously changes the command value of the charge and discharge power (or current) of the storage battery string STR' in the discharged state (which is to be subjected to bypass control) from the current value to "0." On the other hand, the system controller 101 gradually and continuously changes the command value of the charge and discharge power (or current) of one or more of the storage battery strings STR1 to STRm in a charged state (not subject to bypass control) from the current value to the target value.The following describes the processing for changing the instruction value of the charge and discharge power (or current) of each of the storage battery series STR', STR1 to STRm.

[0040] Fig. 2 is a diagram showing the relationship between the command value (hereinafter referred to as the charging power command value) of the charging power and the elapsed time when the charging power command value assigned to the storage battery string STR' to be subjected to bypass control and the other storage battery strings STR1 to STRm is changed. This diagram shows an example in which the charging power command value of the storage battery string STR' to be subjected to bypass control decreases to 0 and in which the charging power command value of the other storage battery strings STR1 to STRm increases. In this example, the charging power command value assigned to the storage battery string STR' to be subjected to bypass control is transferred to the other storage battery strings STR1 to STRm.

[0041] As shown by the solid line in Fig. 2, the charging power command value of the storage battery series STR' to be subjected to the bypass control gradually and continuously decreases from the current value to the target value of "0" over a predetermined period of time. On the other hand, as shown by the dashed line in Fig. 2, the charging power command value of the other storage battery series STR1 to STRm is gradually and continuously increased from the current value to the target value over a predetermined period of time.

[0042] The following describes the details of processing for changing the charging power command value of the storage battery strings STR', STR1 to STRm. Instead of changing the charging power command value of the storage battery strings STR', STR1 to STRm, the charging power command value of the storage battery strings STR', STR1 to STRm can be changed. In this case, the same process as described below can be performed.

[0043] Fig. Figure 3 is a flowchart showing the process for changing the charging power command value of the storage battery series STR', STR1 to STRm. First, the system controller 101 (see Fig. 1) in step S1, the latest information (the detection result and the estimation result) on the state of each of the storage battery rows STR', STR1 to STRm (see Fig. 1) from one of the series controls C' to Cm (see Fig. 1).

[0044] Next, in step S2, the system controller 101 determines whether a bypass control request is received from the series controllers C1 to Cm. If the determination in step S2 is "no," the process proceeds to step S1, and if the determination in step S2 is "yes," the process proceeds to step S3.

[0045] In step S3, the system controller 101 selects one or more of the storage battery strings STR1 to STRm to which the charging power instruction value of the storage battery string STR' to be subjected to bypass control is to be transmitted. In the present step, the storage battery string STR1 to STRm that has the capacity to independently support the charging power of the storage battery string STR' to be subjected to bypass control, or a plurality of storage battery strings STR1 to STRm that have the capacity to jointly support the charging power of the storage battery string STR' to be subjected to bypass control, are selected according to the priority order described above.

[0046] Next, in step S4, the charging power command value of one or more of the storage battery strings STR1 to STRm to which the charging power of the storage battery string STR' to be subjected to bypass control is to be transferred is determined. Specifically, the charging power command value of one or more of the storage battery strings STR1 to STRm selected in step S3 is increased by the charging power command value of the storage battery string STR' to be subjected to bypass control.

[0047] Next, the system controller 101 repeatedly executes the loop processing of steps S5 to S7 until the charging power command value of the storage battery strings STR1 to STRm selected in step S3 reaches the target charging power command value. Here, in steps S5 to S7, the system controller 101 gradually and continuously increases the charging power command value of each of the storage battery strings STR1 to STRm from the current value to the target value by a predetermined amount ΔP1. On the other hand, in steps S5 to S7, the system controller 101 gradually and continuously decreases the charging power command value of the storage battery string STR' to be subjected to bypass control from the current value to 0 by the predetermined amount ΔP1.

[0048] First, in step S5, the system controller 101 changes the charging power command value of the storage battery strings STR', STR1 to STRm by the predetermined amount ΔP1. The predetermined amount ΔP1 is set to a small amount to achieve the purpose of preventing a sudden change in the charging power. When the difference between the current value and the target value of the charging power command value is small, the predetermined amount ΔP1 may be equal to the difference between the current value and the target value of the charging power command value. On the other hand, when the difference between the current value and the target value of the charging power command value is relatively large, the predetermined amount ΔP1 may be smaller than the difference between the current value and the target value of the charging power command value.When the predetermined amount ΔP1 is smaller than the difference between the current value and the target value of the charging power command value, the charging power command value is repeatedly updated a plurality of times.

[0049] Next, in step S6, after transmitting the charging power command value to the series controllers C' and C1 to Cm, the system controller 101 waits for a predetermined period T1. The predetermined period T1 is set taking into account the period required for the series controllers C', C1 to Cm to control the charging power of the storage battery series STR1 to STRm and the rate of change in the charging power. Here, the rate of change in the charging power is set low to achieve the purpose of preventing a sudden change in the charging power.

[0050] Next, in step S7, the system controller 101 determines whether the current charging power command value of each of the storage battery strings STR1 to STRm has reached the target charging power command value of each of the storage battery strings STR1 to STRm. If the determination in step S7 is "no," processing proceeds to step S5, and if the determination in step S7 is "yes," processing proceeds to step S8.

[0051] In step S8, the system controller 101 stops the operation of the power converter PC' corresponding to the storage battery string STR' to be subjected to bypass control. Accordingly, the storage battery string STR' to be subjected to bypass control is in the unloaded state.

[0052] Next, in step S9, the system controller 101 sends a notification of approval of the bypass control request to the row controller C' corresponding to the storage battery row STR' to be subjected to bypass control. Accordingly, the row controller C' executes bypass control on the storage battery row STR' to be subjected to bypass control.

[0053] Next, in step S10, the system controller 101 determines whether the bypass control request from the row controller C' is enabled. Step S10 is repeated until the determination in step S10 is "Yes," and the processing proceeds to step S11 if the determination in step S10 is "Yes."

[0054] In step S11, the system controller 101 assigns 0 to the charging power command value of the storage battery string STR' to be subjected to bypass control. Next, in step S12, the system controller 101 starts the operation of the power converter PC' corresponding to the storage battery string STR' to be subjected to bypass control. This completes the processing.

[0055] Fig. 4 is a diagram showing the relationship between the instruction value (hereinafter referred to as the discharge power instruction value) of the discharge power and the elapsed time when the discharge power instruction value of the storage battery string STR' to be subjected to bypass control and the other storage battery strings STR1 to STRm are changed. This diagram shows an example in which the discharge power instruction value of the storage battery string STR' to be subjected to bypass control decreases to 0 and in which the discharge power instruction value of the other storage battery strings STR1 to STRm increases. In this example, the discharge power instruction value assigned to the storage battery string STR' to be subjected to bypass control is transmitted to the other storage battery strings STR1 to STRm.

[0056] As shown by the solid line in Fig. 4, the discharge power command value of the storage battery series STR' to be subjected to bypass control gradually and continuously decreases from the current value to the target value of "0" over a predetermined period of time. On the other hand, as shown by the dashed line in Fig. 4, the discharge power command value of the other storage battery series STR1 to STRm is gradually and continuously increased from the current value to the target value over a predetermined period of time.

[0057] The following describes the details of processing for changing the discharge power command value of the storage battery strings STR', STR1 to STRm. Instead of changing the discharge power command value of the storage battery strings STR', STR1 to STRm, the discharge current command value of the storage battery strings STR', STR1 to STRm can be changed. In this case, the same process as described below can be performed.

[0058] Fig. Figure 5 is a flowchart showing the process for changing the discharge power command value of the storage battery series STR', STR1 to STRm. First, the system controller 101 (see Fig. 1) in step S101, the latest information (the detection result and the estimation result) on the state of each of the storage battery rows STR', STR1 to STRm (see Fig. 1) from one of the series controls C' to Cm (see Fig. 1).

[0059] Next, in step S102, the system controller 101 determines whether a bypass control request is received from the row controllers C1 to Cm. If the determination in step S102 is "no," processing proceeds to step S101, and if the determination in step S102 is "yes," processing proceeds to step S103.

[0060] Next, in step S103, the system controller 101 selects one or more of the storage battery strings STR1 to STRm to which the discharge power of the storage battery string STR' to be subjected to bypass control is to be transferred. In the present step, the storage battery string STR1 to STRm having the capacity to independently support the discharge power of the storage battery string STR' to be subjected to bypass control, or a plurality of storage battery strings STR1 to STRm having the capacity to jointly support the discharge power of the storage battery string STR' to be subjected to bypass control, are selected according to the priority order described above.

[0061] Next, in step S104, the target discharge power command value of one or more of the storage battery strings STR1 to STRm to which the discharge power of the storage battery string STR' to be subjected to bypass control is to be transferred is determined. Specifically, the discharge power command value of one or more of the storage battery strings STR1 to STRm selected in step S103 is augmented by the discharge power command value of the storage battery string STR' to be subjected to bypass control.

[0062] Next, the system controller 101 repeatedly executes the loop processing of steps S105 to S107 until the discharge power command value of the storage battery strings STR1 to STRm selected in step S103 reaches the target discharge power command value. Here, in steps S105 to S107, the system controller 101 gradually and continuously increases the discharge power command value of each of the storage battery strings STR1 to STRm from the current value to the target value by a predetermined amount ΔP2. On the other hand, in steps S105 to S107, the system controller 101 gradually and continuously decreases the discharge power command value of the storage battery string STR' to be subjected to bypass control from the current value to 0 by the predetermined amount ΔP2.

[0063] First, in step S105, the system controller 101 changes the discharge power command value of the storage battery strings STR', STR1 to STRm by the predetermined amount ΔP2. The predetermined amount ΔP2 is set to a small amount to achieve the purpose of preventing a sudden change in the discharge power. When the difference between the current value and the target value of the discharge power command value is small, the predetermined amount ΔP2 may be equal to the difference between the current value and the target value of the discharge power command value. On the other hand, when the difference between the current value and the target value of the discharge power command value is relatively large, the predetermined amount ΔP2 may be smaller than the difference between the current value and the target value of the discharge power command value.When the predetermined amount ΔP2 is smaller than the difference between the current value and the target value of the discharge power command value, the discharge power command value is repeatedly updated a plurality of times.

[0064] Next, in step S106, the system controller 101 waits for the predetermined period T1 after transmitting the discharge power command value to the series controllers C', C1 to Cm. The predetermined period T1 is set taking into account the period required for the series controllers C', C1 to Cm to control the discharge power of the storage battery series STR', STR1 to STRm and the rate of change in the discharge power. Here, the rate of change in the discharge power is set low to achieve the purpose of preventing a sudden change in the discharge power.

[0065] Next, in step S107, the system controller 101 determines whether the current discharge power command value of each of the storage battery strings STR1 to STRm has reached the target discharge power command value of each of the storage battery strings STR1 to STRm. If the determination in step S107 is "No," processing proceeds to step S105, and if the determination in step S107 is "Yes," processing proceeds to step S108.

[0066] In step S108, the system controller 101 stops the operation of the converter PC' corresponding to the storage battery string STR' to be subjected to bypass control. Accordingly, the storage battery string STR' to be subjected to bypass control is in a discharged state.

[0067] Next, in step S109, the system controller 101 sends a notification of approval of the bypass control request to the row controller C' corresponding to the storage battery row STR' to be subjected to bypass control. Accordingly, the row controller C' executes bypass control on the storage battery row STR' to be subjected to bypass control.

[0068] Next, in step S110, the system controller 101 determines whether the bypass control request from the row controller C' is enabled. Step S110 is repeated until the determination in step S110 is "Yes," and the processing proceeds to step S111 if the determination in step S110 is "Yes."

[0069] In step S111, the system controller 101 assigns 0 to the discharge power command value of the storage battery string STR' to be subjected to bypass control. Next, in step S112, the system controller 101 starts the operation of the power converter PC' corresponding to the storage battery string STR' to be subjected to bypass control. This completes the processing.

[0070] As described above, in the storage battery control device 100 according to the present embodiment, when the bypass control request is transmitted from the series controller C' to the system controller 101, the system controller 101 notifies the series controller C' of the permission for bypass control. At this time, before the system controller 101 notifies the series controller C' of the permission for bypass control, the system controller 101 assigns the command value of the charge and discharge power (or current) assigned to the storage battery series STR' to be subjected to bypass control to one or more of the storage battery series STR1 to STRm that are not to be subjected to bypass control. Then, the system controller 101 stops the operation of the converter PC' of the storage battery series STR' to be subjected to bypass control.

[0071] Here, a sudden change in the charging and discharging power (or current) of the storage battery string STR' occurs when the bypass control is executed on the storage battery string STR' to be subjected to the bypass control while the storage battery string STR' is in the charged state. On the other hand, in the storage battery control device 100 according to the present embodiment, the charging and discharging power (or current) of the storage battery string STR' to be subjected to bypass control is assigned to one or more of the storage battery strings STR1 to STRm, and the bypass control of the storage battery string STR' is executed after the storage battery string STR' is in the unloaded state. Accordingly, it is possible to keep the target charging and discharging power (or current) of the electric power storage system 1 constant when the bypass control is executed.

[0072] Here, in the storage battery control device 100 according to the present embodiment, the system controller 101 assigns the command value of the charge and discharge power (or current) assigned to the storage battery string STR' to be subjected to bypass control to one or more of the storage battery strings STR1 to STRm that are not to be subjected to bypass control. At this time, the system controller 101 repeatedly executes the processing of changing the command value of the charge and discharge power (or current) of the storage battery strings STR', STR1 to STRm toward the command value of the target charge and discharge power (or current) by the predetermined amounts ΔP1 and ΔP2 until the command value reaches the target value. Here, the predetermined amounts ΔP1 and ΔP2 are smaller than the difference between the target value and the current value of the command value of the charge and discharge power (or current).Accordingly, when the command value of the charging and discharging power (or current) of the storage battery strings STR', STR1 to STRm is changed from the current value to the target value, it is possible to cause a sudden change in the charging and discharging power (or current) of the storage battery strings STR', STR1 to STRm and to keep the target charging and discharging power (or current) of the electric power storage system 1 constant.

[0073] Although the present invention has been described above based on the present embodiment, the present invention is not limited to the present embodiment. Modifications may be made without departing from the gist of the present invention, or publicly known or well-known techniques may be appropriately combined.

[0074] For example, in the above embodiment, the command value of the charging and discharging power (or current) of the storage battery strings STR', STR1 to STRm is gradually and continuously changed to the target value over time by the predetermined amount ΔP1 or the predetermined amount ΔP2. For example, when the influence of the change in the charging and discharging power (or current) of the storage battery strings STR', STR1 to STRm on the charging and discharging power (or current) of the electric power storage system 1 is small, the command values of the charging and discharging power (or current) of the storage battery strings STR', STR1 to STRm can be changed all at once.

[0075] In the above embodiment, the system controller 101 transmits the control value of the charge and discharge power (or current) to the series controllers C1 to Cm. However, a controller in which the system controller 101 and the series controllers C1 to Cm are integrated can set the control value of the charge and discharge power (or current) of each of the storage battery series STR1 to STRm.

[0076] Here, the features of the embodiment of the storage battery control device, the electric power storage system and the storage battery control method according to the present invention described above are briefly summarized and listed in the following [1] to [4].

[0077] [1] A storage battery control device (100) for controlling an electric power storage system (1), comprising a plurality of storage battery series (STR1 to STRm) connected in parallel to each other, wherein the storage battery series (STR1 to STRm) comprises a plurality of storage batteries (M1 to Mn) connected in series, a bypass circuit (B1 to Bn) configured to switch the plurality of storage batteries (M1 to Mn) between a connection state and a bypass state, and a power converter (PC1 to PCm) configured to convert input and output power of the storage battery series (STR1 to STRm), wherein the storage battery control device (100) assigns an instruction value for the charging or discharging power or current to the plurality of storage battery series (STR1 to STRm), controls the bypass circuit (B1 to Bn), and controls the power converter (PC1 to PCm), and the storage battery control device (100), before controlling the bypass circuit (B1 to Bn), assigns the instruction value assigned to the storage battery series (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn) to one or more of the storage battery series (STR1 to STRm) not to be controlled by the bypass circuit (B1 to Bn), and stops the power converter (PC1 to PCm) of the storage battery series (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn).

[0078] [2] The storage battery control device (100) according to [1], wherein, when the instruction value assigned to the storage battery series (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn) is assigned to one or more of the storage battery series (STR1 to STRm) not to be controlled by the bypass circuit (B1 to Bn), the processing of increasing the instruction value toward the target value by a change amount smaller than a difference between a target value and a current value is repeatedly executed until the instruction value reaches the target value.

[0079] [3] An electrical power storage system (1) having a plurality of storage battery strings (STR1 to STRm) connected in parallel to each other, and a storage battery control device (100) configured to control the storage battery strings (STR1 to STRm), wherein the storage battery string (STR1 to STRm) comprises a plurality of storage batteries (M1 to Mn) connected in series, a bypass circuit (B1 to Bn) configured to switch the plurality of storage batteries (M1 to Mn) between a connection state and a bypass state, and a power converter (PC1 to PCm) configured to convert input and output power of the storage battery string (STR1 to STRm), in which the storage battery control device (100) assigns an instruction value for the charging or discharging power or current to the plurality of storage battery strings (STR1 to STRm), controls the bypass circuit (B1 to Bn), and controls the power converter (PC1 to PCm), and assigns the instruction value assigned to the storage battery string (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn) to one or more of the storage battery strings not to be controlled by the bypass circuit, and stops the power converter (PC1 to PCm) of the storage battery string (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn) before controlling the bypass circuit (B1 to Bn).

[0080] [4] A storage battery control method executed by a storage battery control device (100) for controlling an electric power storage system (1) comprising a plurality of storage battery strings (STR1 to STRm) connected in parallel to each other, the storage battery string (STR1 to STRm) comprising a plurality of storage batteries (M1 to Mn) connected in series, a bypass circuit (B1 to Bn) configured to switch the plurality of storage batteries (M1 to Mn) between a connection state and a bypass state, and a power converter (PC1 to PCm) configured to convert input and output power of the storage battery string (STR1 to STRm), the storage battery control method comprising: Assigning an instruction value for the charging or discharging power or current of the plurality of storage battery strings (STR1 to STRm), controlling the bypass circuit (B1 to Bn) and controlling the power converter (PC1 to PCm), and before controlling the bypass circuit (B1 to Bn), assigning the instruction value assigned to the storage battery string (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn) to one or more of the storage battery strings (STR1 to STRm) not to be controlled by the bypass circuit (B1 to Bn), and stopping the power converter (PC1 to PCm) of the storage battery string (STR1 to STRm) to be controlled by the bypass circuit (B1 to Bn).

[0081] Although the present invention will be described in detail and with reference to the specific embodiment, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

[0082] This application is based on a Japanese patent application (Japanese Patent Application No. 2022-160011) filed on October 4, 2022, the contents of which are incorporated herein by reference. INDUSTRIAL APPLICABILITY

[0083] According to the present invention, it is possible to provide a storage battery control device, an electric power storage system, and a storage battery control method that enable a target charge and discharge power (or current) of the electric power storage system to be maintained when bypassing control is performed in the electric power storage system in which a plurality of storage battery strings are connected in parallel and each storage battery string is provided with a bypass circuit. The present invention having this effect is useful for the storage battery control device, the electric power storage system, and the storage battery control method. LIST OF REFERENCE SYMBOLS 1 electrical power storage system 100 storage battery control device B1 to Bn bypass switch unit (bypass circuit) M1 to Mn battery module (storage battery) PC1 to PCm, PC' power converter STR1 to STRm, STR' storage battery series ΔP1 predetermined amount (small change amount) ΔP2 predetermined amount (small change amount) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2014-79164 A

[0003] JP 2013-31247 A

[0003] JP 2022-160011

[0082]

Claims

[1] Storage battery control device for controlling an electric power storage system comprising a plurality of storage battery series connected in parallel with each other, wherein the storage battery series comprises a plurality of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery series, wherein the storage battery control device assigns an instruction value for a charge or discharge power or current to the plurality of storage battery series, controls the bypass circuit, and controls the power converter, and wherein the storage battery control device, before controlling the bypass circuit, assigns the control value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stops the power converter of the storage battery string to be controlled by the bypass circuit. [2] The storage battery control device according to claim 1, wherein when the instruction value assigned to the storage battery series to be controlled by the bypass circuit is assigned to one or more of the storage battery series not to be controlled by the bypass circuit, processing of increasing the instruction value toward the target value by a change amount smaller than a difference between a target value and a current value is repeatedly executed until the instruction value reaches the target value. [3] Electrical power storage system, comprising: a plurality of storage battery series connected in parallel; and a storage battery control device configured to control the storage battery rows, where the storage battery series includes: a large number of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery series, wherein the storage battery control device assigns an instruction value of a charge or discharge power or current to the plurality of storage battery series, controls the bypass circuit, and controls the power converter, and wherein, before controlling the bypass circuit, the storage battery control device assigns the control value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stops the power converter of the storage battery string to be controlled by the bypass circuit. [4] A storage battery control method, executed by a storage battery control device, for controlling an electric power storage system including a plurality of storage battery series connected in parallel with each other, the storage battery series comprising: a large number of storage batteries connected in series, a bypass circuit configured to switch the plurality of storage batteries between a connection state and a bypass state, and a power converter configured to convert input and output power of the storage battery series, wherein the storage battery control method comprises: Assigning an instruction value for a charge or discharge power or current of the plurality of storage battery strings, controlling the bypass circuit and controlling the power converter, and before controlling the bypass circuit, assigning the instruction value assigned to the storage battery string to be controlled by the bypass circuit to one or more of the storage battery strings not to be controlled by the bypass circuit, and stopping the power converter of the storage battery string to be controlled by the bypass circuit.

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