JP2017011849A - Power storage system for fixation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system for fixation capable of suppressing the self discharge amount, while maintaining high state of charge of a nickel hydrogen secondary battery.SOLUTION: A controller 130 controls a charge discharge device 120 to execute first control for lowering the state quantity by a predetermined amount from a target value by charging a nickel hydrogen secondary battery 110 until the state quantity, indicating the state of charge of the nickel hydrogen secondary battery 110, indicates charging complete, and performing discharge of the nickel hydrogen secondary battery 110 after charging the nickel hydrogen secondary battery 110. The controller 130 controls the charge discharge device 120 to execute second control of discharging to an electric load 300, on the outside of a power storage system for fixation 100, after execution of the first control.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a stationary power storage system, and more particularly to a stationary power storage system using a nickel-metal hydride secondary battery used in a vehicle.

  Patent Document 1 discloses a stationary power storage system. This stationary power storage system is used as a stationary power source in stores, factories, houses, and the like, and is connected to electrical devices such as houses. The stationary power storage system is connected to an external power source and can store power supplied from the external power source. This stationary power storage system includes a nickel metal hydride secondary battery. The nickel metal hydride secondary battery includes a used (used) secondary battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle. Thus, in this stationary power storage system, used nickel-metal hydride secondary batteries for vehicles are reused.

JP 2014-166015 A

  From the viewpoint of power saving, the movement of power peak cut is spreading. The power peak cut is to reduce the power consumption of the commercial power supply in the time zone corresponding to the peak of power demand. In order to cope with the power peak cut, the stationary power storage system charges the nickel metal hydride secondary battery in a time zone other than the time zone corresponding to the peak power demand, and uses the charged power, for example, the peak power demand time. Used for belts. Therefore, in the stationary power storage system, the interval from when the nickel metal hydride secondary battery is charged to when power consumption is started tends to increase. When this interval becomes long, the amount of self-discharge of the nickel metal hydride secondary battery becomes large, which is a problem.

  In addition, in the stationary power storage system, in order to increase the power that can be consumed in the time zone corresponding to the peak of power demand as much as possible, the current storage amount with respect to the SOC of the nickel metal hydride secondary battery (the fully charged state of the nickel metal hydride secondary battery) It is desirable to keep it as high as possible before using electricity. However, in the state where the SOC of the nickel metal hydride secondary battery is high, a self-discharge reaction is likely to occur.

  This invention was made in order to solve such a subject, The objective is the electrical storage system for stationary which can suppress a self-discharge amount, maintaining the charge condition of a nickel-hydrogen secondary battery high Is to provide.

  A stationary power storage system according to an aspect of the present invention is a stationary power storage system using a nickel-hydrogen secondary battery that has been used in a vehicle, and includes a storage battery, a charge / discharge device, and a control device. The storage battery is constituted by a nickel hydride secondary battery. The charge / discharge device charges and discharges the storage battery. The control device controls the charge / discharge device. The control device charges the storage battery until the state quantity (SOC) indicating the state of charge of the storage battery reaches a target value indicating completion of charging, and discharges the storage battery after charging the storage battery to determine the state quantity from the target value. The charging / discharging device is controlled so as to execute the first control for quantitative reduction. And a control apparatus controls a charging / discharging apparatus so that the 2nd control which discharges with respect to the electric load outside the stationary electrical storage system may be performed after execution of 1st control.

  Thus, in this stationary power storage system, after the state quantity indicating the state of charge of the nickel hydride secondary battery reaches the target value, the state quantity is reduced by a predetermined amount (for example, 1% in SOC). Thereby, the self-discharge amount of the nickel metal hydride secondary battery is suppressed as compared with the case where the state quantity is not reduced by a predetermined amount. Therefore, according to this stationary power storage system, the self-discharge amount can be suppressed even when the SOC of the nickel-hydrogen secondary battery is high.

  According to the present invention, it is possible to provide a stationary power storage system that can suppress the self-discharge amount while maintaining the state of charge of the nickel-hydrogen secondary battery high.

It is a block diagram which shows the structure of the electrical storage system for stationary. It is a flowchart for demonstrating charging / discharging control in the electrical storage system for stationary. It is a figure which shows the transition of SOC of a nickel metal hydride secondary battery. It is a figure which compares the breakdown of the discharge amount of the nickel hydride secondary battery by the presence or absence of 1st discharge control.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<Configuration of stationary storage system>
FIG. 1 is a block diagram illustrating a configuration of a stationary power storage system 100 according to this embodiment. Referring to FIG. 1, stationary power storage system 100 is used as a stationary power source used in, for example, a store, a factory, a house, and the like. The stationary power storage system 100 is connected to an electrical load 300 installed in a factory or the like. Thereby, stationary power storage system 100 can supply electric power to electric load 300. The stationary power storage system 100 is connected to an external power source 200. Thereby, stationary power storage system 100 can store power supplied from external power supply 200.

  Examples of the electrical load 300 include home appliances such as equipment and an air conditioner. Examples of the external power source 200 include a solar power generator, a private power generator, and commercial power supplied with power via a transmission line.

  The stationary power storage system 100 can communicate with the power consumption monitoring device 400. The power consumption monitoring device 400 monitors the power consumption of each electric load in the premises where the stationary power storage system 100 is installed. For example, the power consumption monitoring device 400 constantly monitors the power consumption of the electric load 300. The power consumption monitoring apparatus 400 notifies the stationary power storage system 100 of a discharge request when the total power consumption of each electric load installed on the premises exceeds a predetermined amount. The stationary power storage system 100 acquires a discharge request from the power consumption monitoring device 400 and starts supplying power to the electric load 300. Moreover, the power consumption monitoring apparatus 400 has a clock function. For example, the power consumption monitoring apparatus 400 notifies the stationary power storage system 100 of a charge request for the nickel metal hydride secondary battery 110 when a time zone in which the electricity bill is low is reached by using this clock function. The stationary power storage system 100 acquires a charge request from the power consumption monitoring device 400 and starts charging the nickel metal hydride secondary battery 110.

  The stationary power storage system 100 includes a nickel metal hydride secondary battery 110, a charge / discharge device 120, a control device 130, and a communication device 140. The nickel metal hydride secondary battery 110 is a used nickel metal hydride secondary battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle.

  The charge / discharge device 120 is a device that charges and discharges the nickel-hydrogen secondary battery 110. For example, the charging / discharging device 120 is a device that performs power conversion. The charging / discharging device 120 converts AC power supplied from the external power source 200 into DC power, and charges the nickel-hydrogen secondary battery 110 with the DC power. Further, the charging / discharging device 120 converts the DC power supplied from the nickel hydride secondary battery 110 into AC power, and supplies the AC power to the electric load 300.

  The communication device 140 is a communication module that communicates with the power consumption monitoring device 400. For example, the communication device 140 includes a communication module that can handle communication via a wired LAN or a wireless LAN.

  The control device 130 is a controller that controls the charge / discharge device 120. The control device 130 receives a power supply instruction from the power consumption monitoring device 400 to the electric load 300 when the total power consumption in the premises exceeds a predetermined amount. When control device 130 receives a power supply instruction from power consumption monitoring device 400, control device 130 controls charging / discharging device 120 to discharge the power stored in nickel-hydrogen secondary battery 110.

  The control device 130 calculates the SOC of the nickel hydride secondary battery 110 by using the detection value of a current sensor (not shown) that detects the input / output current of the nickel hydride secondary battery 110. The control device 130 controls charging / discharging of the nickel hydride secondary battery 110 according to the SOC state of the nickel hydride secondary battery 110.

  As described above, in the stationary power storage system 100, for example, the nickel metal hydride secondary battery 110 is charged in a time zone where the electricity bill is low (for example, at midnight), and the total power consumption in the premises is limited. Discharge is performed during a time period that is equal to or greater than a fixed amount (for example, a daytime period). Therefore, there is a tendency that the interval from when the nickel hydride secondary battery 110 is charged to when power consumption is started becomes longer. When this interval becomes long, the amount of self-discharge of the nickel metal hydride secondary battery 110 becomes large, which is a problem.

  In addition, in order to maximize the power that can be consumed in the time zone when the total power consumption of the premises is equal to or greater than a predetermined amount, in the stationary power storage system 100, the SOC of the nickel metal hydride secondary battery 110 is increased as much as possible before discharging. It is desirable to keep it. However, when the SOC of the nickel metal hydride secondary battery 110 is high, a self-discharge reaction is likely to occur.

  In stationary power storage system 100 according to the present embodiment, control device 130 charges nickel metal hydride secondary battery 110 until the SOC of nickel metal hydride secondary battery 110 reaches a target value indicating the completion of charging, and uses nickel hydride secondary battery. The charging / discharging device 120 is controlled to execute the first control for reducing the SOC by a predetermined amount from the target value by discharging the nickel-hydrogen secondary battery 110 after charging the secondary battery 110. Then, control device 130 controls charging / discharging device 120 so as to execute second control for discharging electric load 300 outside stationary power storage system 100 after the execution of first control.

  Thus, in this stationary power storage system 100, after the SOC of the nickel metal hydride secondary battery 110 reaches the target value, the SOC is decreased by a predetermined amount (for example, 1%). Thereby, the self-discharge amount of the nickel metal hydride secondary battery 110 is suppressed as compared with the case where the SOC is not decreased by a predetermined amount. Therefore, according to this stationary power storage system, the self-discharge amount can be suppressed even when the SOC of the nickel hydride secondary battery 110 is high.

  In this embodiment, the nickel hydride secondary battery 110 is charged and discharged based on the SOC of the nickel hydride secondary battery 110. However, it is not necessarily limited to such a configuration. For example, the nickel hydride secondary battery 110 may be charged and discharged based on the voltage value of the nickel hydride secondary battery 110. In short, the nickel hydride secondary battery 110 may be charged and discharged based on the state quantity indicating the charge state of the nickel hydride secondary battery 110.

  The mechanism of self-discharge of the nickel hydride secondary battery is as follows. The positive electrode of the nickel hydride secondary battery 110 is made of nickel hydroxide. The negative electrode of the nickel hydrogen secondary battery 110 is made of a hydrogen storage alloy. The hydrogen storage alloy is an alloy having a property of taking in hydrogen. When the nickel metal hydride secondary battery 110 is charged, nickel hydroxide reacts with hydroxide ions at the positive electrode of the nickel metal hydride secondary battery 110 to generate nickel oxyhydroxide. In the high SOC state immediately after the completion of charging, the molecular structure of nickel oxyhydroxide is unstable, so nickel oxyhydroxide tends to change to nickel hydroxide having a stable molecular structure. Immediately after the completion of charging of the nickel metal hydride secondary battery 110, the nickel oxyhydroxide changes to nickel hydroxide by reacting with water. This reaction is a self-discharge reaction.

<Charge / discharge control>
FIG. 2 is a flowchart for explaining charge / discharge control of the nickel metal hydride secondary battery 110 in the stationary power storage system 100. In stationary power storage system 100, for example, nickel metal hydride secondary battery 110 is charged in a time zone (for example, midnight time zone) when the electricity bill is low. In this case, for example, when a charge request notified from the power consumption monitoring device 400 is acquired when a time period in which the electricity rate is low has arrived, the control device 130 charges the nickel metal hydride secondary battery 110. The charging / discharging device 120 is controlled to start (step S100).

  When the charging of the nickel metal hydride secondary battery 110 is started, the control device 130 uses the detection value of a current sensor (not shown) to set the target value (90%) at which the SOC of the nickel metal hydride secondary battery 110 indicates the completion of charging. Is determined (step S110). When it is determined that the SOC has not reached the target value (NO in step S110), control device 130 controls charging / discharging device 120 so as to continue charging of nickel-hydrogen secondary battery 110. Hereinafter, the control for charging the nickel metal hydride secondary battery 110 until the SOC reaches the target value is referred to as charge control.

  On the other hand, when it is determined that the SOC has reached the target value (YES in step S110), control device 130 controls charging / discharging device 120 so as to quickly start discharging (step S120). When the discharge is started, control device 130 determines whether or not the SOC of nickel hydride secondary battery 110 has decreased by a predetermined amount (for example, 1%) (step S130). Hereinafter, the control for reducing the SOC by a predetermined amount from the target value is referred to as first discharge control. When it is determined that the SOC has not decreased by a predetermined amount (NO in step S130), control device 130 controls charging / discharging device 120 to continue discharging.

  On the other hand, when it is determined that the SOC has decreased by a predetermined amount (YES in step S130), control device 130 controls charging / discharging device 120 to stop discharging (step S140). When the discharge is stopped, the control device 130 determines whether or not a power supply start instruction is issued from the power consumption monitoring device 400 (step S150). For example, the power consumption monitoring device 400 issues a power supply instruction to the electric load 300 to the control device 130 when the total power consumption in the premises where the stationary power storage system 100 is installed exceeds a predetermined amount.

  If no power supply start instruction is issued from power consumption monitoring apparatus 400 (NO in step S150), control apparatus 130 waits until a power supply start instruction is issued from power consumption monitoring apparatus 400. In this standby state, the nickel metal hydride secondary battery 110 is self-discharged.

  On the other hand, when a power supply start instruction is issued from power consumption monitoring device 400 (YES in step S150), control device 130 controls charging / discharging device 120 to start power supply to electric load 300. (Step S160). Hereinafter, control in which electric power stored in the nickel hydride secondary battery 110 is discharged with respect to the electric load 300 is referred to as second discharge control. When the power supply to the electric load 300 is completed, the processing is completed.

  FIG. 3 is a diagram showing the transition of the SOC of the nickel metal hydride secondary battery 110. With reference to FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the SOC of the nickel metal hydride secondary battery 110. A broken line indicated by a solid line is a transition of the SOC of the nickel-metal hydride secondary battery 110 when the charging method in the stationary power storage system 100 of this embodiment is used. A broken line indicated by a broken line is a transition of the SOC of the nickel metal hydride secondary battery 110 when the second discharge control is performed without performing the first discharge control after the charge control is performed. .

  According to the charging method in stationary power storage system 100 of this embodiment, the charging control is executed until the SOC of nickel hydride secondary battery 110 is changed from 0 (%) to 90 (%). When the SOC reaches 90 (%) at time t1, the first discharge control is executed until the SOC decreases by 1 (%). That is, the first discharge control is executed until the discharge capacity B1 is discharged. When the SOC decreases by 1 (%) at time t2, the nickel metal hydride secondary battery 110 enters a standby state and the nickel metal hydride secondary battery 110 starts self-discharge. The self-discharge in this case is more gradual than in the broken line. As described above, when the SOC is increased to the target value (90%) and then the SOC is decreased by a predetermined amount (1%), compared with the case where the SOC is increased to the target value and the SOC is not decreased by the predetermined amount. The inventors of the present application have found that the self-discharge of the nickel metal hydride secondary battery 110 becomes gentle.

  When the control device 130 receives a power supply start instruction from the power consumption monitoring device 400 at time t3, second discharge control is executed. Since the self-discharge from time t2 to t3 is more gradual than in the broken line, the state of high SOC is maintained at time t3 as compared to the broken line. Therefore, after time t3, larger electric power is supplied to the electric load 300 than in the case of the broken line. That is, only the discharge capacity A1 can be discharged in the case of the broken line, whereas the discharge capacity B2 (> discharge capacity A1) can be discharged in the case of the solid line.

  Thus, in stationary power storage system 100 of this embodiment, control device 130 charges nickel hydride secondary battery 110 until the SOC of nickel hydride secondary battery 110 reaches a target value indicating completion of charging (charging). Control), and discharging the nickel metal hydride secondary battery 110 after charging the nickel metal hydride secondary battery 110 to reduce the SOC from the target value by a predetermined amount (first discharge control) so as to execute the first control. The charging / discharging device 120 is controlled. Then, after the execution of the first control, the control device 130 is charged and discharged so as to execute the second control (second discharge control) for discharging the electric load 300 outside the stationary power storage system 100. The device 120 is controlled.

  In this stationary power storage system 100, after the SOC of the nickel metal hydride secondary battery 110 reaches the target value, the SOC is decreased by a predetermined amount. Thereby, the self-discharge amount of the nickel metal hydride secondary battery 110 is suppressed as compared with the case where the SOC is not decreased by a predetermined amount. Therefore, according to this stationary power storage system, the self-discharge can be suppressed even when the SOC of the nickel metal hydride secondary battery 110 is high.

<Comparison of discharge capacity>
FIG. 4 is a diagram comparing the breakdown of the discharge capacity of the nickel hydride secondary battery 110 with and without the first discharge control. Referring to FIG. 4, the left side is a breakdown of the discharge capacity of nickel-metal hydride secondary battery 110 when the first discharge control is not executed. The right side is a breakdown of the discharge capacity of the nickel metal hydride secondary battery 110 in the stationary energy storage system 100 of this embodiment.

  When the first discharge control is not executed, the discharge capacity due to self-discharge is A2 (Wh), and the discharge capacity in the second discharge control is A1 (Wh). On the other hand, in stationary electricity storage system 100 of this embodiment, the discharge capacity due to self-discharge is B3 (Wh), the discharge capacity in the first discharge control is B1 (Wh), and in the second discharge control The discharge capacity is B2 (Wh).

  Thus, when comparing the discharge capacity by self-discharge, when the first discharge control is not executed, the discharge capacity is A2 (Wh), whereas in the stationary power storage system 100, the discharge capacity is B3. (Wh). B3 (Wh) has a discharge capacity of about 60% with respect to A2 (Wh). That is, in the stationary power storage system 100, the self-discharge amount is improved by about 40 (%). Further, the sum of the discharge capacity due to self-discharge in stationary electricity storage system 100 and the discharge capacity in the first discharge control is smaller than the self-discharge amount when the first discharge control is not executed. The stationary power storage system 100 can supply power to a commercial system. Therefore, the electric power discharged by the first discharge control is supplied to the electric load 300 and is not lost and is not wasted.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 100 Stationary electrical storage system, 110 Nickel metal hydride secondary battery, 120 Charge / discharge device, 130 Control device, 140 Communication device, 200 External power supply, 300 Electric load, 400 Power consumption monitoring device

Claims (1)

A stationary energy storage system using a nickel-metal hydride secondary battery used in a vehicle,
A storage battery composed of the nickel-hydrogen secondary battery;
A charging / discharging device for charging / discharging the storage battery;
A control device for controlling the charge / discharge device,
The controller is
The storage battery is charged until the state quantity indicating the state of charge of the storage battery reaches a target value indicating completion of charging, and the storage battery is discharged after the storage battery is charged, thereby discharging the storage battery from the target value by a predetermined amount. Controlling the charging / discharging device to perform the first control to reduce,
A stationary power storage system that controls the charging / discharging device so as to execute a second control that discharges an electric load external to the stationary power storage system after the first control is performed.

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