Control device of power storage system

Abstract

To provide a power storage system that appropriately raises the temperature of a storage battery in a power storage system while suppressing increases in costs and losses in the power storage system.SOLUTION: A control device of a power storage system disclosed herein is a control device of a power storage system including a plurality of storage batteries connected in parallel, which determines whether the battery temperatures of the plurality of storage batteries are below a predetermined low temperature threshold; when there are a plurality of low temperature storage batteries whose battery temperatures are below the low temperature threshold, discharges or charges one of the low temperature storage batteries while charging or discharging the remaining low temperature storage battery; when there is only one low temperature storage battery, determines a storage battery other than the low temperature storage battery that is to exchange power with the low temperature storage battery so as to minimize loss; and discharges or charges the low temperature storage battery while charging or discharging the determined storage battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device for a power storage system including a plurality of storage batteries connected in parallel. [Background technology]

[0002] Conventionally, a known power storage system includes a plurality of storage batteries (secondary batteries), a connection circuit that connects the plurality of storage batteries in series or parallel, a detection unit that detects the temperature of the plurality of storage batteries, a heating device such as a heater that raises the temperature of the plurality of storage batteries, a heating switch connected between the plurality of storage batteries and the heating device, and a control unit that controls the connection circuit and the heating switch (see, for example, Patent Document 1). When discharging the plurality of storage batteries, the control unit of this power storage system controls the connection circuit so that the plurality of storage batteries are connected in parallel and turns off the heating switch. When charging the plurality of storage batteries and the temperature of the plurality of storage batteries is equal to or higher than a threshold, the control unit controls the connection circuit so that the plurality of storage batteries are connected in series and turns off the heating switch. When charging the plurality of storage batteries and the temperature of the plurality of storage batteries is lower than the threshold, the control unit controls the connection circuit so that the plurality of storage batteries are connected in parallel and turns on the heating switch. This means that even when multiple storage batteries are connected to a heating device during charging, the voltage applied to the heating device can be made the same as the voltage of all the storage batteries connected in parallel, thereby suppressing the voltage applied to the heating device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-046365 Summary of the Invention [Problem to be solved by the invention]

[0004] However, providing a heating device for heating the batteries in a power storage system increases the cost of the power storage system. Also, when there is variation in the temperatures of the batteries in the power storage system, it is preferable to heat only the batteries that require heating in order to suppress an increase in loss.

[0005] Therefore, a main object of the present disclosure is to appropriately increase the temperature of a storage battery in a power storage system while suppressing increases in costs and losses in the power storage system. [Means for solving the problem]

[0006] The control device for a power storage system disclosed herein is a control device for a power storage system including a plurality of storage batteries connected in parallel, and determines whether the battery temperatures of the plurality of storage batteries are below a predetermined low temperature threshold, and when there are a plurality of low temperature storage batteries whose battery temperatures are below the low temperature threshold, discharges or charges one of the low temperature storage batteries while charging or discharging the remaining low temperature storage battery, and when there is only one low temperature storage battery, determines a storage battery other than the low temperature storage battery that will exchange power with the low temperature storage battery so as to minimize loss, and discharges or charges the low temperature storage battery while charging or discharging the determined storage battery.

[0007] The control device of the power storage system of the present disclosure, when there are multiple low-temperature storage batteries whose battery temperatures are below a low-temperature threshold, discharges or charges one of the multiple low-temperature storage batteries and charges or discharges the remaining low-temperature storage batteries. This allows power to be exchanged only between the multiple low-temperature storage batteries that need to be heated, thereby raising the temperatures of the multiple low-temperature storage batteries while suppressing an increase in loss. Furthermore, when there is only one low-temperature storage battery, the control device determines a storage battery other than the low-temperature storage battery that will exchange power with the low-temperature storage battery so as to minimize loss. The control device then discharges or charges the low-temperature storage battery and charges or discharges the determined storage battery. This makes it possible to appropriately determine the number of other storage batteries that exchange power with the low-temperature storage battery and raise the temperature of the low-temperature storage battery while suppressing an increase in loss. Furthermore, a power storage system including such a control device can omit a heating device for heating the multiple storage batteries. As a result, the control device for a power storage system according to the present disclosure makes it possible to appropriately raise the temperatures of a plurality of storage batteries in the power storage system while suppressing increases in costs and losses in the power storage system. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram illustrating a power storage system including a control device according to the present disclosure. [Figure 2] 4 is a flowchart illustrating a routine executed by a control device of the present disclosure. [Figure 3] 4 is a flowchart illustrating a routine executed by a control device of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0010] Fig. 1 is a schematic configuration diagram showing a power storage system 1 including a system control device 10 as a control device of the present disclosure. The power storage system 1 shown in the figure is a stationary power storage system capable of supplying power to batteries of electric vehicles such as battery electric vehicles (BEVs) and hybrid vehicles (HEVs), not shown, and to ordinary households, and is connected to a power grid PS. As shown in Fig. 1, the power storage system 1 includes, in addition to the system control device 10, a power conditioner (hereinafter referred to as "PCS") 2, a power conditioner control device (hereinafter referred to as "PCSECU") 3, an energy management device (hereinafter referred to as "EMS") 4, and a plurality of power storage units 5.

[0011] The power system PS supplies AC power and may include a power generation system that generates power using renewable energy sources such as wind power and solar power. The PCS2 includes an inverter connected to the power system PS and a pair of input / output terminals T, and can convert AC power from the power system PS into DC power and DC power from multiple power storage units 5 into AC power. The PCSECU3 includes a computer (not shown) and controls the PCS2. The EMS4 includes at least one server (computer) and sends command signals to the PCSECU3 and the system control device 10 according to the power supply status and power demand status of the power system PS.

[0012] Each power storage unit 5 includes a storage battery 50, a DC / DC converter (voltage conversion circuit) 51, a pair of relays 52, capacitors 53 and 54, a converter control device (hereinafter referred to as "CNVECU") 55, and a battery control device (hereinafter referred to as "battery ECU") 57. Each storage battery 50 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery, and is connected to a corresponding DC / DC converter 51 via a pair of relays 52 and a capacitor 53. Each DC / DC converter 51 includes two transistors (e.g., insulated gate bipolar transistors) Tra and Trb, two diodes Da and Db connected in parallel in opposite directions to the transistors Tra and Trb, and a reactor L, and is connected in parallel to the pair of input / output terminals T via a capacitor 54. Each capacitor 53 smoothes voltage fluctuations between the corresponding storage battery 50 and DC / DC converter 51. The capacitor 54 smoothes voltage fluctuations between the corresponding DC / DC converter 51 and the pair of input / output terminals T.

[0013] Each CNVECU 55 includes a computer and a drive circuit (not shown), and exchanges information with the system control device 10. Each CNVECU 55 outputs a PWM signal to the gate terminals of the transistors Tra and Trb of the corresponding DC / DC converter 51, and adjusts the duty ratio of the PWM signal based on the target discharge voltage Vd or the target charge voltage Vc from the system control device 10. The BATECU 57 includes a computer (not shown), and exchanges information with the system control device 10. The BATECU 57 acquires the charge / discharge current, charge / discharge voltage, battery temperature Tb, etc. of the storage battery 50 detected by a sensor (not shown), and acquires the SOC, etc. of the storage battery 50 based on the acquired information.

[0014] The system control device 10 includes a computer (not shown) and exchanges information with the EMS 4 and the CNVECU 55 and BATECU 57 of each power storage unit 5 via at least one of wired communication and wireless communication. The system control device 10 acquires the battery temperature Tb and SOC of each storage battery 50 from the BATECU 57 of each power storage unit 5 and transmits a target discharge voltage Vd or a target charge voltage Vc to the CNVECU 55 of each power storage unit 5 in response to a discharge command or a charge command from the EMS 4. Upon receiving the target discharge voltage Vd or the target charge voltage Vc, the CNVECU 55 outputs a PWM signal having a duty ratio in accordance with the target discharge voltage Vd or the target charge voltage Vc to the DC / DC converter 51. This makes it possible to supply power from each storage battery 50 to a load connected to the input / output terminal T, or to charge each storage battery 50 with power from the power grid PS converted by the PCS 2.

[0015] Furthermore, the system control device 10 determines whether the PCS2 is in an unloaded state (whether the power storage system 1 is in a standby state) based on information from the EMS 4. Furthermore, when power is not exchanged between the power storage system 1 and the power grid PS and the PCS2 is in an unloaded state, the system control device 10 determines whether the battery temperature Tb of the storage battery 50 of each power storage unit 5 is equal to or lower than a predetermined low-temperature threshold Tref (for example, a value around 0°C). Then, when there is at least one storage battery 50 (hereinafter referred to as "low-temperature storage battery 50x") whose battery temperature Tb is equal to or lower than the low-temperature threshold Tref, the system control device 10 discharges or charges the low-temperature storage battery 50x and transmits a target discharge voltage Vd or a target charge voltage Vc to the corresponding CNVECU 55 so that power is exchanged between the low-temperature storage batteries 50x or between the low-temperature storage battery 50x and the remaining storage batteries 50. This makes it possible to raise the temperature of the low-temperature storage batteries 50x and maintain good output characteristics of each storage battery 50 by exchanging power between multiple low-temperature storage batteries 50x or between the low-temperature storage batteries 50x and the remaining storage batteries 50 without using a battery heating device such as a heater.

[0016] Next, the procedure for raising the temperature of the low-temperature storage battery 50x will be described in detail with reference to Figures 2 and 3. Figures 2 and 3 are flowcharts showing a battery temperature raising routine executed by the system control device 10. The battery temperature raising routine is executed by the system control device 10 when the system control device 10 determines, based on information from the EMS 4, that the PCS 2 is in an unloaded state (the power storage system 1 is in a standby state).

[0017] 2, when the timing for executing the battery warm-up routine arrives, the system control device 10 acquires the battery temperature Tb of each storage battery 50 from the BATECU 57 of each power storage unit 5 (step S100), and determines whether or not there is a low-temperature storage battery 50x whose battery temperature Tb is equal to or lower than the low-temperature threshold value Tref (step S110). If there is no low-temperature storage battery 50x (step S110: NO), the system control device 10 ends the routine shown in FIG. 2 etc. at that time.

[0018] Furthermore, if a low-temperature storage battery 50x is present (step S110: YES), the system control device 10 determines whether or not multiple low-temperature storage batteries 50x are present (step S120). If multiple low-temperature storage batteries 50x are present (step S120: YES), the system control device 10 transmits a signal to the CNVECU 55 of the power storage unit 5 that does not include a low-temperature storage battery 50x to stop (shut down) the corresponding DC / DC converter 51 (step S130).

[0019] After the process of step S130, the system control device 10 compares the battery temperatures Tb of the plurality of low-temperature storage batteries 50x and determines whether or not a temperature that can be considered as the lowest temperature exists (step S140). If the battery temperature Tb of any one of the low-temperature storage batteries 50x is lower than the battery temperatures Tb of the remaining low-temperature storage batteries 50x, or if the battery temperatures Tb of the plurality of low-temperature storage batteries 50x are substantially the same and lower than the battery temperatures Tb of the remaining low-temperature storage batteries 50x, the system control device 10 determines that a lowest temperature exists (step S140: YES) and selects the low-temperature storage battery 50x with the lowest temperature (step S150).

[0020] In step S150, if the battery temperature Tb of any one of the low-temperature storage batteries 50x is lower than the battery temperatures Tb of the remaining low-temperature storage batteries 50x, the system control device 10 selects that one of the low-temperature storage batteries 50x as the low-temperature storage battery 50x with the lowest temperature. Also, in step S150, if the battery temperatures Tb of the plurality of low-temperature storage batteries 50x are substantially the same and lower than the battery temperatures Tb of the remaining low-temperature storage batteries 50x, the system control device 10 selects one of the plurality of low-temperature storage batteries 50x with substantially the same battery temperature Tb as the low-temperature storage battery 50x according to a predetermined selection procedure. In this case, for example, the one with the shortest charge / discharge time may be selected as the low-temperature storage battery 50x from the plurality of low-temperature storage batteries 50x with substantially the same battery temperature Tb.

[0021] Furthermore, when the battery temperatures Tb of the plurality of low-temperature storage batteries 50x are substantially the same, that is, are within a predetermined narrow range (step S140), the system control device 10 determines that there is no lowest temperature (step S140: NO), and selects one of the plurality of low-temperature storage batteries 50x as the low-temperature storage battery 50x with the lowest temperature according to a predetermined selection procedure (step S155).In this case, too, the one with the shortest charge / discharge time, for example, may be selected from the plurality of low-temperature storage batteries 50x as the low-temperature storage battery 50x with the lowest temperature.

[0022] After the process of step S150 or S155, the system control device 10 determines whether the SOC of the selected lowest-temperature low-temperature storage battery 50x is equal to or higher than a predetermined relatively high first threshold S1 (step S160). If the SOC of the lowest-temperature low-temperature storage battery 50x is equal to or higher than the first threshold S1 and is relatively high (step S160: YES), the system control device 10 transmits a target discharge voltage Vd corresponding to, for example, the battery temperature Tb and the SOC to the CNVECU 55 of the power storage unit 5 including the low-temperature low-temperature storage battery 50x, and transmits a target charge voltage Vc lower than the target discharge voltage Vd for the lowest-temperature low-temperature storage battery 50x to the CNVECU 55 of the power storage unit 5 including the remaining low-temperature storage batteries 50x other than the low-temperature low-temperature storage battery 50x (step S170).

[0023] As a result, the low-temperature storage battery 50x with the lowest temperature is discharged, and the remaining low-temperature storage batteries 50x are charged with power from the low-temperature storage battery 50x with the lowest temperature. As a result, by exchanging power among the plurality of low-temperature storage batteries 50x, it is possible to raise the temperatures of the low-temperature storage battery 50x with the lowest temperature and the remaining low-temperature storage batteries 50x, thereby maintaining good output characteristics of each storage battery 50. The processing of step S170 is continuously executed until the battery temperatures Tb of the plurality of low-temperature storage batteries 50x reach a temperature rise stop threshold that is set to be slightly higher than the low-temperature threshold Tref, for example, and the routine shown in FIG. 2 etc. ends when the battery temperatures Tb of the plurality of low-temperature storage batteries 50x reach the temperature rise stop threshold.

[0024] Furthermore, if the SOC of the lowest-temperature low-temperature storage battery 50x is less than the first threshold value S1 (step S160: NO), the system control device 10 determines whether the SOC of the selected lowest-temperature low-temperature storage battery 50x is equal to or less than a predetermined relatively low second threshold value S2 that is lower than the first threshold value S1 (step S165). If the SOC of the lowest-temperature low-temperature storage battery 50x is equal to or less than the second threshold value S2 and is relatively low (step S165: YES), the system control device 10 transmits a target charge voltage Vc corresponding to, for example, the battery temperature Tb and the SOC to the CNVECU 55 of the power storage unit 5 including the low-temperature low-temperature storage battery 50x, and transmits a target discharge voltage Vd that is higher than the target charge voltage Vc for the lowest-temperature low-temperature storage battery 50x to the CNVECU 55 of the power storage unit 5 including the remaining low-temperature storage batteries 50x other than the low-temperature low-temperature storage battery 50x (step S180).

[0025] As a result, power is discharged from the remaining low-temperature storage batteries 50x other than the low-temperature storage battery 50x with the lowest temperature, and the low-temperature storage battery 50x is charged with power from the remaining low-temperature storage batteries 50x. As a result, by exchanging power among the plurality of low-temperature storage batteries 50x, it is possible to raise the temperatures of the low-temperature storage battery 50x with the lowest temperature and the remaining low-temperature storage batteries 50x, thereby maintaining good output characteristics of each storage battery 50. The processing of step S180 is also continuously executed until the battery temperatures Tb of the plurality of low-temperature storage batteries 50x reach the temperature rise stop threshold, and the routine shown in FIG. 2 etc. ends when the battery temperatures Tb of the plurality of low-temperature storage batteries 50x reach the temperature rise stop threshold.

[0026] Furthermore, when the SOC of the lowest-temperature low-temperature storage battery 50x exceeds the second threshold value S2 (step S165: NO), the system control device 10 determines whether to discharge or charge the lowest-temperature low-temperature storage battery 50x according to a predetermined procedure, and then, when discharging the lowest-temperature low-temperature storage battery 50x, executes a process similar to step S170 and ends the routine shown in Figure 2 etc., and when charging the lowest-temperature low-temperature storage battery 50x, executes a process similar to step S180 and ends the routine shown in Figure 2 etc. (step S190). In these cases, too, by exchanging power among the plurality of low-temperature storage batteries 50x, it is possible to raise the temperatures of the lowest-temperature low-temperature storage battery 50x and the remaining low-temperature storage batteries 50x, and maintain good output characteristics of each storage battery 50.

[0027] On the other hand, if only one low-temperature storage battery 50x exists (step S120: NO), the system control device 10 determines whether the SOC of the one low-temperature storage battery 50x, i.e., the low-temperature storage battery 50x with the lowest temperature, is equal to or higher than the first threshold value S1 (step S200), as shown in Fig. 3. If the SOC of the low-temperature storage battery 50x is equal to or higher than the first threshold value S1 and is relatively high (step S200: YES), the system control device 10 determines the storage battery 50 to be charged with power from the one low-temperature storage battery 50x (step S210).

[0028] In step S210, the system control device 10 sets a target discharge voltage Vd for the low-temperature storage battery 50x according to, for example, the battery temperature Tb and SOC, and then determines the number of storage batteries 50 to be charged (the number of storage batteries) based on the target discharge voltage Vd. In this embodiment, a map (not shown) is prepared in advance that defines the relationship between the target discharge voltage Vd and the number of storage batteries that minimizes loss in the power storage system 1 when one low-temperature storage battery 50x is discharged and another storage battery 50 is charged, and the system control device 10 determines the number of storage batteries according to the target discharge voltage Vd from the map. Furthermore, in step S210, the system control device 10 determines the storage batteries 50 to be charged based on the number of storage batteries and the battery temperature Tb and SOC of each storage battery 50 other than the low-temperature storage battery 50x.

[0029] Then, the system control device 10 transmits the target discharge voltage Vd set in step S210 to the CNVECU 55 of the power storage unit 5 including the one low-temperature storage battery 50x, and transmits a target charge voltage Vc lower than the target discharge voltage Vd for the low-temperature storage battery 50x to the CNVECU 55 of the power storage unit 5 including the storage battery 50 to be charged determined in step S210 (step S220). As a result, the one low-temperature storage battery 50x is discharged, and the target storage battery 50 is charged with power from the low-temperature storage battery 50x. As a result, by exchanging power between the one low-temperature storage battery 50x and the other storage batteries 50, it is possible to raise the temperature of the one low-temperature storage battery 50x and maintain good output characteristics of each storage battery 50. The process of step S220 is continuously executed until the battery temperature Tb of the one low-temperature storage battery 50x reaches the temperature rise stop threshold, and the routine shown in FIG. 3 etc. ends when the battery temperature Tb of the one low-temperature storage battery 50x reaches the temperature rise stop threshold.

[0030] Furthermore, if the SOC of the one low-temperature storage battery 50x is less than the first threshold value S1 (step S200: NO), the system control device 10 determines whether the SOC of the one low-temperature storage battery 50x is equal to or less than the second threshold value S2 (step S205). If the SOC of the low-temperature storage battery 50x is equal to or less than the second threshold value S2 and is relatively low (step S205: YES), the system control device 10 determines the storage battery 50 to be discharged in order to charge the one low-temperature storage battery 50x (step S230).

[0031] In step S230, the system control device 10 sets a target charging voltage Vc for the low-temperature storage battery 50x according to, for example, the battery temperature Tb and SOC, and then determines the number of storage batteries 50 to be discharged (the number of storage batteries) based on the target charging voltage Vc. In this embodiment, a map (not shown) is prepared in advance that defines the relationship between the target charging voltage Vc and the number of storage batteries that minimizes loss in the power storage system 1 when discharging other storage batteries 50 to charge one low-temperature storage battery 50x, and the system control device 10 determines the number of storage batteries according to the target charging voltage Vc from the map. Furthermore, in step S230, the system control device 10 determines the storage batteries 50 to be discharged based on the number of storage batteries and the battery temperatures Tb and SOC of the storage batteries 50 other than the low-temperature storage battery 50x.

[0032] Next, the system control device 10 transmits the target charging voltage Vc set in step S230 to the CNVECU 55 of the power storage unit 5 including the one low-temperature storage battery 50x, and transmits a target discharging voltage Vd higher than the target charging voltage Vc for the low-temperature storage battery 50x to the CNVECU 55 of the power storage unit 5 including the storage battery 50 to be discharged determined in step S230 (step S240). As a result, the corresponding storage batteries 50 other than the low-temperature storage battery 50x are discharged, and the one low-temperature storage battery 50x is charged with power from the discharged storage battery 50. As a result, by exchanging power between the one low-temperature storage battery 50x and the other storage batteries 50, it is possible to raise the temperature of the low-temperature storage battery 50x and maintain good output characteristics of each storage battery 50. The processing of step S240 is continuously executed until the battery temperature Tb of the one low-temperature storage battery 50x reaches the temperature rise stop threshold, and the routine shown in Figure 3 etc. ends when the battery temperature Tb of the one low-temperature storage battery 50x reaches the temperature rise stop threshold.

[0033] Furthermore, when the SOC of the one low-temperature storage battery 50x is above the second threshold value S2 (step S205: NO), the system control device 10 determines whether to discharge or charge the one low-temperature storage battery 50x according to a predetermined procedure, and then, when discharging the one low-temperature storage battery 50x, executes the same processing as steps S210-S220 to end the routine shown in Figure 2 etc., and when charging the one low-temperature storage battery 50x, executes the same processing as steps S230-S240 to end the routine shown in Figure 3 etc. (steps S250, S260). In these cases, too, by exchanging power between the one low-temperature storage battery 50x and the other storage batteries 50, it is possible to raise the temperature of the one low-temperature storage battery 50x and maintain good output characteristics of each storage battery 50.

[0034] As described above, when there are a plurality of low-temperature storage batteries 50x whose battery temperature Tb is equal to or lower than the low-temperature threshold value Tref (step S120: YES), the system control device 10 of the power storage system 1 discharges or charges one of the plurality of low-temperature storage batteries 50x and charges or discharges the remaining low-temperature storage batteries 50x (steps S130-S190). This allows power to be exchanged only between the plurality of low-temperature storage batteries 50x whose temperatures should be increased, thereby making it possible to increase the temperatures of the plurality of low-temperature storage batteries 50x while suppressing an increase in loss.

[0035] Furthermore, when there is only one low-temperature storage battery 50x (step S120: NO), the system control device 10 determines a storage battery 50 other than the low-temperature storage battery 50x that exchanges power with the low-temperature storage battery 50x so as to minimize loss (steps S210, S230, S250). Then, the system control device 10 discharges or charges the one low-temperature storage battery 50x and charges or discharges the determined storage battery 50 (steps S220, S240, S260). This makes it possible to appropriately determine the number of other storage batteries 50 that exchange power with the one low-temperature storage battery 50x and suppress an increase in loss, while raising the temperature of the one low-temperature storage battery 50x.

[0036] Furthermore, in the power storage system 1 including the system control device 10, it is possible to omit a battery heating device such as a heater for heating the multiple storage batteries 50. As a result, it is possible to appropriately heat the multiple storage batteries 50 of the power storage system 1 while suppressing increases in costs and losses of the power storage system 1. The system control device 10 may be applied to a power storage device other than a stationary power storage system 1, for example, a power storage device mounted on an electric vehicle.

[0037] Furthermore, the invention of the present disclosure is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely one specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0038] The invention of the present disclosure can be used in the energy storage system manufacturing industry and the like. [Explanation of symbols]

[0039] 1 Energy storage system, 2 Power conditioner (PCS), 3 Power conditioner control unit (PCSECU), 4 Energy management unit (EMS), 5 Energy storage unit, 50 Storage battery, 50x Low temperature storage battery, 51 DC / DC converter (voltage converter), 52 Relay, 53, 54 Capacitor, 55 Converter control unit (CNVECU), 57 Battery control unit (BATECU), 10 System control unit, PS Power system, T Input / output terminal.

Claims

[Claim 1] A control device for a power storage system including a plurality of storage batteries connected in parallel, determining whether the battery temperatures of the plurality of storage batteries are equal to or lower than a predetermined low temperature threshold; When there are a plurality of low-temperature storage batteries whose battery temperature is equal to or lower than the low-temperature threshold, discharging or charging any one of the low-temperature storage batteries and charging or discharging the remaining low-temperature storage batteries; A control device for a power storage system that, when there is only one low-temperature storage battery, determines a storage battery other than the low-temperature storage battery that will exchange power with the low-temperature storage battery so as to minimize loss, discharges or charges the low-temperature storage battery, and charges or discharges the determined storage battery.

Images