JP2015133816A - Charge/discharge controller, power storage system, charge/discharge instruction device, charge/discharge control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a load of a charge/discharge controller be relatively small and make it possible to deal with large scale photovoltaic power generation and a large scale wind power generation station.SOLUTION: A charge/discharge controller for controlling charge/discharge with respect to a plurality of secondary batteries connected in parallel to an inverter, comprises: a State Of Charge (SOC) acquisition unit for acquiring the SOC of each of the secondary batteries; a SOC determination unit for determining whether or not all of the SOCs of the secondary batteries acquired by the SOC acquisition unit are within a predetermined SOC range; an instruction following control unit for controlling the inverter so that the inverter makes the secondary batteries output current shown by a charge/discharge instruction, when it is determined that all of the SOCs of the secondary batteries acquired by the SOC acquisition unit are within the predetermined SOC range; and a constant voltage control unit for controlling the inverter so that the inverter applies a predetermined voltage to a secondary battery, when it is determined that the secondary battery's SOC of all of the SOCs of the secondary batteries acquired by the SOC acquisition unit is out of the SOC range.

Description

  The present invention relates to a charge / discharge control device, a power storage system, a charge / discharge command device, a charge / discharge control method, and a program.

  When large-scale solar power generation (mega solar) or large-scale wind power plant (wind farm) operates in large quantities, output fluctuations using power storage devices such as lithium-ion batteries, taking into account the effects of fluctuations in the output on the grid It is thought that there will be a need to implement suppression. That is, it is conceivable that output fluctuations in solar power generation and wind power generation are smoothed by the power storage system.

Here, several techniques have been proposed in relation to the power storage system. For example, the storage battery control system described in Patent Literature 1 includes a plurality of storage batteries provided in an electric power system and a storage battery control device. The storage battery control device is communicably connected to the plurality of storage batteries and the power management device. The storage battery control device acquires storage battery information including charge / discharge performance and remaining battery capacity from each storage battery, acquires power supply / demand prediction information indicating prediction of power supply / demand in a predetermined range from the power management device, and stores the storage battery information and power Based on the supply and demand prediction information, an individual charge / discharge amount is determined for each storage battery, and the determined individual charge / discharge amount is transmitted to each storage battery. Each storage battery operates based on the individual charge / discharge amount received from the storage battery control device.
In patent document 1, it is supposed that the some storage battery connected to an electric power grid | system is used effectively by this storage battery control system.

JP2013-106372A

  When the scale of the power storage system is increased to accommodate large-scale solar power generation or large-scale wind power plants, the charge / discharge control device (storage battery control device) is applied to each storage battery as in the technique described in Patent Document 1. In the method of determining and transmitting the charge / discharge amount, the load on the charge / discharge control device increases.

  The present invention relates to a charge / discharge control device, a power storage system, a charge / discharge command device, a charge / discharge control method, and a load that is relatively small for the charge / discharge control device and that can be applied to large-scale solar power generation and large-scale wind power plants. Provide a program.

  The charging / discharging control apparatus by the 1st aspect of this invention is a charging / discharging control apparatus which controls charging / discharging of the some secondary battery connected in parallel with the inverter, Comprising: The charging rate of each said secondary battery is acquired. A charging rate acquisition unit, a charging rate determination unit that determines whether or not the charging rates of all the secondary batteries acquired by the charging rate acquisition unit are within a predetermined charging rate range, and the charging rate acquisition unit A command follow-up control unit that controls the inverter to output the current indicated by the charge / discharge command from the secondary battery when it is determined that the charge rates of all the acquired secondary batteries are within a predetermined charge rate range; When the charge rate of the secondary battery acquired by the charge rate acquisition unit is determined to be beyond the charge rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. And a constant voltage control unit.

  The charge / discharge control device according to the second aspect of the present invention is a charge / discharge control device for controlling charge / discharge of a secondary battery connected to an inverter, wherein a charge / discharge command for the secondary battery is changed from charge to discharge. Or, when it is determined that the charge / discharge command is switched by the charge / discharge switching determining unit and the charge / discharge switching determining unit that determines whether or not the switching from discharging to charging is performed, the change rate of the charging / discharging current is a predetermined change When the rate control unit that controls charging / discharging of the secondary battery by the inverter and the charging / discharging switching determination unit determine that the charging / discharging command has not been switched so as to be within the rate range, the secondary A command follow-up control unit that controls the inverter to output a current indicated by the charge / discharge command from a battery.

  A power storage system according to a third aspect of the present invention includes an inverter, a plurality of secondary batteries connected in parallel to the inverter, and a charge / discharge control device that controls charging / discharging of the plurality of secondary batteries. The charging / discharging control device includes a charging rate acquisition unit that acquires a charging rate of each of the secondary batteries, and charging rates of all the secondary batteries acquired by the charging rate acquisition unit are within a predetermined charging rate range. If it is determined that the charging rate of all the secondary batteries acquired by the charging rate determination unit and the charging rate acquisition unit are within a predetermined charging rate range, the current indicated by the charge / discharge command is determined. The command follow-up control unit that controls the inverter to output from the secondary battery and the charge rate of the secondary battery acquired by the charge rate acquisition unit are determined to include those exceeding the charge rate range. A predetermined voltage on the secondary battery A constant voltage control unit for controlling the inverter as applied, comprises a.

  A power storage system according to a fourth aspect of the present invention includes an inverter, a secondary battery connected to the inverter, and a charge / discharge control device that controls charge / discharge of the secondary battery, and the charge / discharge control device. Is determined that the charge / discharge command has been switched by the charge / discharge switching determination unit for determining whether the charge / discharge command for the secondary battery has been switched from charge to discharge, or from discharge to charge, and the charge / discharge switch determination unit. The rate control unit for controlling the charging / discharging of the secondary battery by the inverter and the charge / discharge switching determination unit so that the rate of change of the charge / discharge current falls within a predetermined range of the rate of change. A command follow-up control unit that controls the inverter to output the current indicated by the charge / discharge command from the secondary battery when it is determined that the charge / discharge command has not been switched; That.

  A charge / discharge command device according to a fifth aspect of the present invention is a charge / discharge command device that commands charge / discharge to a plurality of the power storage systems, and is a charge / discharge command device that acquires each charge / discharge measurement value of the power storage system. A discharge measurement value acquisition unit, a difference calculation unit that calculates a difference between the charge / discharge measurement value and the charge / discharge command value, and a difference between the charge / discharge measurement value and the charge / discharge command value is equal to or less than a predetermined threshold value And a correction unit that performs correction to reduce a difference between the charge / discharge measured value of the entire power storage system and the charge / discharge command value with respect to the charge / discharge command value of the power storage system.

  A charge / discharge control method according to a sixth aspect of the present invention is a charge / discharge control method for controlling charge / discharge of a plurality of secondary batteries connected in parallel to an inverter, and obtains a charge rate of each of the secondary batteries. A charging rate acquisition step, a charging rate determination step for determining whether or not the charging rates of all secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range, and the charging rate acquisition step Command follow-up control that controls the inverter to output the current indicated by the charge / discharge command from the secondary battery when it is determined that the charge rates of all the secondary batteries acquired in step S are within a predetermined charge rate range. And when the charge rate of the secondary battery acquired in the charge rate acquisition step is determined to be beyond the charge rate range, the input voltage is applied to the secondary battery. And a constant voltage control step of controlling over data.

  A charge / discharge control method according to a seventh aspect of the present invention is a charge / discharge control method for controlling charge / discharge of a secondary battery connected to an inverter, wherein a charge / discharge command for the secondary battery is changed from charge to discharge, Or, when it is determined that the charge / discharge switching command is switched in the charge / discharge switching determination step and the charge / discharge switching determination step for determining whether or not switching from discharging to charging is performed, the rate of change of the charging / discharging current is determined in advance. When it is determined that the charge / discharge command is not switched in the rate control step for controlling charge / discharge of the secondary battery by the inverter and the charge / discharge switching determination step so as to be within the range of the change rate, A command follow-up control step for controlling the inverter to output a current indicated by the charge / discharge command from a secondary battery.

  A program according to an eighth aspect of the present invention is a computer that controls charging / discharging of a plurality of secondary batteries connected in parallel to an inverter, a charge rate acquisition step of acquiring a charge rate of each of the secondary batteries, A charging rate determination step for determining whether or not the charging rates of all the secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range; and all the secondary batteries acquired in the charging rate acquisition step Command follow-up control step for controlling the inverter to output the current indicated by the charge / discharge command from the secondary battery when it is determined that the charge rate of the battery is within a predetermined charge rate range; and the charge rate acquisition step When it is determined that there is a charge rate of the secondary battery acquired in step 4 that exceeds the charge rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. Is a program for executing the constant voltage control step that.

  According to a ninth aspect of the present invention, there is provided a program for controlling a charge / discharge of a secondary battery connected to an inverter to determine whether a charge / discharge command for the secondary battery is switched from charge to discharge or from discharge to charge. When it is determined that the charge / discharge command is switched in the charge / discharge switching determination step and the charge / discharge switching determination step, the change rate of the charge / discharge current is within a predetermined change rate range. And when the charge / discharge command is determined not to be switched in the rate control step for controlling charge / discharge of the secondary battery by the inverter and the charge / discharge switching determination step, the charge / discharge command is transmitted from the secondary battery. Is a program for executing a command follow-up control step for controlling the inverter so as to output the current indicated by.

  According to the above-described charge / discharge control device, power storage system, charge / discharge command device, charge / discharge control method and program, the load on the charge / discharge control device is relatively small and can be applied to large-scale solar power generation or large-scale wind power plants. Can respond.

It is explanatory drawing which shows the example of the electric power grid | system in which the electrical storage apparatus in one Embodiment of this invention is used. It is a schematic block diagram which shows the apparatus structure of the electrical storage system in the embodiment. It is a schematic block diagram which shows the function structure of the charging / discharging control apparatus in the same embodiment. It is a schematic block diagram which shows the function structure of the charging / discharging instruction | command apparatus in the embodiment. It is explanatory drawing which shows the equivalent circuit of the electromotive force and internal resistance of the secondary battery in the embodiment. In the same embodiment, it is explanatory drawing which shows the example of the electric current which flows into a secondary battery, when charging by command follow-up mode. In the same embodiment, it is explanatory drawing which shows the example of the electric current which flows into a secondary battery, when charging by switching from command follow mode to constant voltage mode. In the same embodiment, it is explanatory drawing which shows the example of the process sequence which a charging / discharging control apparatus selects the mode of charging / discharging. In the embodiment, it is explanatory drawing which shows the example of the process sequence which a rate control part performs the necessity of a rate limiter, and the setting of a rate limiter value.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.
FIG. 1 is an explanatory diagram illustrating an example of an electric power system in which a power storage facility according to an embodiment of the present invention is used. In the figure, in addition to the power storage facility 1, a power plant 911, a large-scale natural energy power generation facility 912, and a load 921 are connected to the power system 9.

The power plant 911 is a power generation facility that generates power using fuel energy, such as coal power generation, petroleum power generation, or LNG power generation.
The large-scale natural energy power generation facility 912 is a power generation facility that generates power using natural energy, such as solar power generation, solar thermal power generation, or wind power generation. The amount of power generated by the large-scale natural energy power generation facility 912 fluctuates due to the influence of solar radiation and wind power.
The load 921 is a facility that consumes electric power, such as a factory facility, a commercial facility, or a house.

  The power storage facility 1 smoothes the output fluctuation of the large-scale natural energy power generation facility 912. Here, in order to cope with the output fluctuation of the large-scale natural energy power generation facility 912, it is conceivable to adjust the output of the power plant 911. However, in general, it takes time to change the power generation amount of a thermal power generation facility or the like, and there is a possibility that it cannot cope with the output fluctuation of the large-scale natural energy power generation facility 912. Therefore, the power storage facility 1 stores the surplus power of the power plant 911 and discharges when the power is insufficient, thereby smoothing the power.

  The power storage facility 1 includes a plurality of power storage systems 10 and a charge / discharge command device 20. Each of the power storage systems 10 performs charge / discharge according to a charge / discharge command from the charge / discharge command device 20, thereby smoothing the power. The charge / discharge command apparatus 20 is realized by, for example, a computer executing a program.

  Note that the number of large-scale natural energy power generation facilities 912 and loads 921 connected to the power system 9 may be one or more. Moreover, the number of the power plants 911 connected to the power system 9 may be 0 or more. That is, a configuration in which the power plant 911 is not connected to the power system 9 may be used. The number of power storage systems included in the power storage facility 1 may be plural.

FIG. 2 is a schematic configuration diagram illustrating a device configuration of the power storage system 10. The power storage system 10 includes a secondary battery 11, an inverter 12, and a charge / discharge control device 13.
The number of inverters 12 included in the power storage system 10 may be plural. As for the number of secondary batteries 11, a plurality of secondary batteries 11 connected in parallel may be connected to each of the inverters 12. As shown in FIG. 2, the secondary batteries 11 connected in series may be connected in parallel and connected to the inverter 12.

The secondary battery 11 is connected in parallel to the inverter 12 (the secondary batteries 11 are connected in parallel and connected to the inverter 12), and is charged and discharged according to the control of the inverter 12.
The inverter 12 is provided between the power system 9 and the secondary battery 11, and AC / DC conversion (AC (Alternating Current) / DC (AC) between the AC current on the power system 9 side and the DC current on the secondary battery 11 side is provided. Direct Current) conversion). Further, the inverter 12 causes the secondary battery 11 to charge / discharge according to the control of the charge / discharge control device 13. The charging / discharging the inverter 12 performs on the secondary battery 11 includes a command following mode in accordance with a command from the charging / discharging control device 13 and a constant voltage (CV) mode in which charging or discharging is performed with a constant voltage.

The charge / discharge control device 13 outputs a charge / discharge command for the secondary battery 11 to each of the inverters 12 based on a command from the charge / discharge command device 20 (FIG. 1). The charge / discharge control device 13 is realized by, for example, a computer executing a program.
FIG. 3 is a schematic block diagram showing a functional configuration of the charge / discharge control device 13. In the figure, the charge / discharge control device 13 includes a communication unit 131, a charge / discharge switching determination unit 132, a charge rate determination unit 133, a command follow-up control unit 134, a constant voltage control unit 135, and a rate control unit 136. And a rate limiter storage unit 137.

  The communication unit 131 communicates with other devices. In particular, communication unit 131 receives a charge / discharge command (for example, a command for output power of power storage system 10 or a command for output current of power storage system 10) from charge / discharge command device 20 (FIG. 1). The communication unit 131 receives battery state information such as SOC (state of charge) from each of the secondary batteries 11. The communication unit 131 corresponds to an example of a charging rate acquisition unit. In addition, the communication unit 131 transmits a charge / discharge command for the secondary battery 11 to the inverter 12.

The charge / discharge switching determination unit 132 determines whether the charge / discharge command for the secondary battery 11 is switched from charge to discharge or from discharge to charge.
Specifically, the charge / discharge switching determination unit 132 first acquires the charge / discharge command received by the communication unit 131 from the charge / discharge command device 20, and determines whether the charge / discharge command is a charge command or a discharge command. The charge / discharge switching determination unit 132 outputs information indicating the determination result of the charge command or discharge command and the command value to the charge rate determination unit 133.

  Further, the charge / discharge switching determination unit 132 stores the determination result of the charge command or the discharge command, and compares the previous determination result with the current determination result, so that the charge / discharge command for the secondary battery 11 is charged. It is determined whether or not switching from discharging to charging or from discharging to charging is performed. The charge / discharge switching determining unit 132 outputs a determination result to the rate control unit 136 as to whether or not the charge / discharge command for the secondary battery 11 has been switched from charging to discharging or from discharging to charging.

The charging rate determination unit 133 determines whether the charging rates of all the secondary batteries 11 acquired (received) by the communication unit 131 are within a predetermined charging rate range. Specifically, the charging rate determination unit 133 stores the following threshold values in advance, and compares each charging rate of the secondary battery 11 acquired by the communication unit 131 with the threshold value.
A: Charging rate upper limit value B: Charging mode switching threshold value C: Discharging mode switching threshold value D: Charging rate lower limit value The charging rate determination unit 133 uses information indicating the distinction between a charging command or a discharging command and a command value as a determination result. Based on the command follow-up control unit 134 or the constant voltage control unit 135 based on this.

  When the charge rate determination unit 133 determines that the charge rates of all the secondary batteries 11 acquired (received) by the communication unit 131 are within the predetermined charge rate range, the command follow-up control unit 134 is the charge / discharge command device 20. The inverter 12 is controlled to output the current indicated by the charge / discharge command from the secondary battery 11.

  More specifically, when it is determined that the charging rates of all the secondary batteries 11 are less than the charging mode switching threshold B during charging, the charging rate determination unit 133 provides information indicating a charging command and a command value. Output to the follow-up control unit 134. In addition, when it is determined that the charging rate of all the secondary batteries 11 is larger than the discharge mode switching threshold C during discharging, the charging rate determination unit 133 sends information indicating the discharge command and a command value to the command tracking control unit 134. Output.

  When the command follow-up control unit 134 acquires information indicating the distinction between the charge command or the discharge command and the command value from the charge rate determination unit 133, the command follow-up control unit 134 obtains the obtained command value (the charge / discharge command from the charge / discharge command device 20). Value), a charge / discharge command for each of the inverters 12 (for example, a command of output power from the inverter 12) is generated. Then, the command tracking control unit 134 controls the inverter 12 by transmitting the generated charge / discharge command to each inverter 12 via the communication unit 131.

When the charging rate determination unit 133 determines that the charging rate of the secondary battery 11 acquired by the communication unit 131 exceeds the predetermined charging rate range, the constant voltage control unit 135 determines that the secondary battery 11 The inverter 12 is controlled to apply a predetermined voltage.
More specifically, when the charging rate determination unit 133 determines that there is a secondary battery 11 having a charging rate equal to or higher than the charging mode switching threshold B at the time of charging, in principle, information indicating a charging command, a command value, Is output to the constant voltage control unit 135. In addition, when the charging rate determination unit 133 determines that there is a secondary battery 11 having a charging rate equal to or lower than the charging mode switching threshold C at the time of discharging, in principle, constant voltage control is performed on information indicating a discharge command and a command value. To the unit 135.

  Then, when the constant voltage control unit 135 acquires the information indicating the charging command from the charging rate determination unit 133, the constant voltage control unit 135 issues a command for causing the secondary battery 11 to perform constant voltage charging at a preset charging voltage value. It transmits to each of the inverters 12 via 131. In addition, when the constant voltage control unit 135 acquires information indicating the discharge command from the charging rate determination unit 133, the constant voltage control unit 135 issues a command for causing the secondary battery 11 to perform constant voltage discharge with a preset discharge voltage value. It transmits to each of the inverters 12 via 131.

When the charge / discharge switching determination unit 132 determines that the charge / discharge command has been switched from charge to discharge or from discharge to charge, the rate control unit 136 has a change rate of the charge / discharge current within a predetermined change rate range. The charging / discharging of the secondary battery 11 by the inverter 12 is controlled so as to be inside.
Specifically, the rate control unit 136 stores the charge / discharge command value output from the command tracking control unit 134 or the constant voltage control unit 135. Then, the rate control unit 136 subtracts the previous charge / discharge command value (for example, power command value) from the current charge / discharge command value output from the command follow-up control unit 134 or the constant voltage control unit 135, and thereby the charge / discharge command value. The amount of change is calculated. Then, the rate control unit 136 compares the calculated change amount with a preset allowable range of the change amount, and when it is determined that the change amount is larger than the upper limit of the allowable value, the rate control unit 136 limits the upper limit of the allowable value. . Similarly, when it is determined that the change amount is smaller than the allowable lower limit (allowable lower limit <0), the rate control unit 136 limits the allowable value lower limit.

On the other hand, when the charge / discharge switching determination unit 132 determines that the charge / discharge command is not switched from charge to discharge or from discharge to charge, the rate control unit 136 determines whether the command follow-up control unit 134 or the constant voltage control unit 135 The command value is output to the communication unit 131 as it is.
Accordingly, the command follow-up control unit 134 controls the inverter 12 to output the current indicated by the charge / discharge command from the secondary battery 11 when the charge / discharge switching determination unit 132 determines that the charge / discharge command has not been switched.

  The rate control unit 136 prevents the inverter 12 from stopping by limiting the rate of change of the charge / discharge current. Here, the inverter 12 is provided with a system abnormality detection system. When a system abnormality is detected, the output of the inverter 12 is temporarily stopped (for example, for 5 seconds). Further, since the scale of the power storage system 10 is large, the influence of the output fluctuation of the power storage system 10 on the voltage of the power system 9 is large. Therefore, when the charge / discharge command transmitted from the charge / discharge control device 13 to the inverter 12 is switched from charge to discharge or from discharge to charge due to the sudden change in output of the large-scale natural energy power generation facility 912 (FIG. 1) Anomaly detection system may operate. When the system abnormality detection system operates and the output from the inverter 12 is stopped, the response (smoothing) to the power fluctuation of the power system 9 is delayed.

Therefore, the rate control unit 136 applies a rate limiter to the command from the charge / discharge command device 20 to suppress a sudden change in the output power of the power storage system 10. Thereby, a sudden change in the system voltage can be avoided, and the output stop of the inverter 12 due to the operation of the system abnormality detection system can be avoided. The unit of the rate limiter is watt / second.
Further, the rate control unit 136 does not limit the command value except when switching between charge and discharge, and transmits the command value as it is to the inverter 12 via the communication unit 131. Thereby, the electrical storage system 10 can respond quickly to fluctuations in power supply and demand in the power system 9 such as fluctuations in the output of the large-scale natural energy power generation facility 912.

The rate limiter storage unit 137 stores in advance the state of each device connected to the power system 9, the necessity / unnecessity of the rate limiter, and the rate limiter value if necessary.
The data stored in the rate limiter storage unit 137 is calculated by simulation, for example. Specifically, a system condition for operating the system abnormality detection system of the inverter 12 and a rate limiter set value for avoiding the operation of the system abnormality detection system are calculated by power flow calculation (simulation).

  The system conditions here are, for example, the power generation amount of the power plant 911, the power consumption of the factory as the load 921, and the like. The power flow calculation here is a calculation for obtaining the amplitude and phase of the voltage and current, the active power, and the reactive power in the generator bus, the power transmission line, and the load bus. The power flow calculation is performed for the purpose of, for example, a power system operation plan.

FIG. 4 is a schematic block diagram showing a functional configuration of the charge / discharge command apparatus 20. In the figure, the charge / discharge command apparatus 20 includes a communication unit 201, a charge / discharge command generation unit 202, a difference calculation unit 203, a difference determination unit 204, and a correction unit 205.
The charge / discharge command device 20 commands each of the power storage systems 10 to charge / discharge.
The communication unit 201 communicates with other devices. In particular, the communication unit 201 acquires (receives) charge / discharge measurement values of the power storage system 10 from each of the power storage systems 10. The communication unit 201 corresponds to an example of a charge / discharge measurement value acquisition unit.

The charge / discharge command generation unit 202 generates a charge / discharge command (for example, a power command or a current command) for each of the power storage systems 10. For example, the charge / discharge command generation unit 202 calculates a charge / discharge command for each of the power storage systems 10 based on an automatically generated operation plan or an operation plan received by an operator.
The difference calculation unit 203 calculates, for each power storage system 10, the difference between the charge / discharge measurement value received by the communication unit 201 and the charge / discharge command value generated by the charge / discharge command generation unit 202.
For each power storage system 10, the difference determination unit 204 compares the difference calculated by the difference calculation unit 203 with a predetermined threshold value, and detects the power storage system 10 whose magnitude is less than or equal to the threshold value. The power storage system 10 detected by the difference determination unit 204 is considered to be a power storage system 10 that has good tracking to the command value.

The correction unit 205 measures the charge / discharge measurement value and the charge / discharge command value of the entire power storage system with respect to the charge / discharge command value of the power storage system 10 whose magnitude of the difference between the charge / discharge measurement value and the charge / discharge command value is equal to or less than a predetermined threshold The correction which reduces the difference with is performed.
Specifically, the correction unit 205 adds the differences for each power storage system 10 calculated by the difference calculation unit 203 to obtain a correction target value. Then, the correction unit 205 distributes the obtained correction target value to the power storage system 10 detected by the difference determination unit 204.

Various methods can be used as a method for the correction unit 205 to distribute the correction target value to the power storage system 10. For example, the power storage system 10 may be prioritized, and the correction unit 205 may distribute the correction target values in order from the power storage system 10 with the highest priority. Alternatively, the correction unit 205 may acquire the chargeable / dischargeable remaining amount for each power storage system 10 and distribute the correction target value according to the ratio of the chargeable / dischargeable remaining amount.
In order to avoid overshoot due to correction, the correction unit 205 may set the correction target value to a smaller value, for example, by multiplying 0.9 by the total difference for each power storage system 10.

Next, with reference to FIGS. 5 to 8, switching of the charge / discharge mode performed by the charge / discharge control device 13 will be described.
FIG. 5 is an explanatory diagram showing an equivalent circuit of the electromotive force and the internal resistance of the secondary battery 11. In the figure, E11 indicates a cell voltage, and E21 indicates a cell open voltage. R11 indicates an internal resistance, and E22 indicates a voltage drop due to the internal resistance. I11 indicates a cell current.

  The cell voltage E11 is a superposition of the cell open voltage E21 and the voltage drop E22 (total during charging, difference during discharging). For example, when the storage system 10 is stopped, the cell open voltage = cell voltage = 3.5 volts (V), and at the time of charging, the cell open voltage = 3.5 volts and the cell voltage = 4 volts, the voltage drop Is 0.5 volts.

Here, when the power storage system 10 includes a plurality of secondary batteries 11 as shown in FIG. 5 and the plurality of secondary batteries 11 are charged, the charging state of each of the two secondary batteries 11 out of the plurality will be described. . In order to make the explanation easy to understand, in the following explanation, it is assumed that the cell voltages of the two secondary batteries 11 are the same. In the following description, it is assumed that the charging rates (battery open voltage) of the two secondary batteries 11 are the same in the initial state and the deterioration states (internal resistance) of the battery cells are different.
As described above, when the cell voltages E11 of the two secondary batteries are the same and the cell open voltage E21 is the same (therefore, the voltage drop is the same), the two secondary batteries 11 are connected in parallel as described above. If the cell voltages are the same, a large amount of current flows through the secondary battery 11 having a battery cell with a small internal resistance R11.
For example, when the cell voltage E11 of one of the two secondary batteries 11 is 4.0 volts and the cell open voltage E21 is 3.5 volts, the voltage drop E22 is 0.5 volts. When the internal resistance of the one secondary battery 11 is 10 milliohms (mΩ), the cell current I11 is 50 amperes (A). On the other hand, when the voltage drop E22 of the other secondary battery 11 out of the two is 0.5 volts as described above and the internal resistance is 5 milliohms, the cell current I11 of the other secondary battery 11 is 100. Become an ampere.

In the command following mode, due to the difference in the cell current as described above, a large amount of current flows through the battery having a small internal resistance, and charging proceeds.
On the other hand, as described later, in the constant voltage mode, a large amount of current flows through a battery having a large internal resistance, and charging proceeds. Therefore, when the power storage system 10 including the secondary batteries 11 connected in parallel switches from the command following mode to the constant voltage mode, the charging of the secondary battery 11 having a battery cell with a small internal resistance proceeds from the state where the internal resistance is increased. Can be switched to a state in which charging of a secondary battery having a large battery cell proceeds. By performing such switching processing, the power storage system 10 reduces variation in the charging rate between the secondary battery 11 having a battery cell with a low internal resistance and the secondary battery 11 having a battery cell with a high internal resistance. be able to.

Next, assuming that the degradation state (internal resistance) of the two secondary battery 11 internal battery cells is the same, and the cell open-circuit voltages are different due to different charging rates of these battery cells, The charging status of the secondary battery 11 will be described below.
In such a situation, since the cell voltage E11 and the internal resistance R11 are the same and the cell open voltage E21 is different, a large amount of current flows through the battery having a low cell open voltage.
For example, when the cell voltage E11 of one of the two secondary batteries 11 is 4.0 volts and the cell open voltage E21 is 3.5 volts, the voltage drop E22 is 0.5 volts. When the internal resistance R11 of the one secondary battery 11 is 10 milliohms, the cell current I11 is 50 amperes.
On the other hand, when the cell voltage E11 of the other secondary battery 11 out of the two is 4.0 volts and the cell open voltage E21 is 3.9 volts, the voltage drop E22 is 0.1 volts. When the internal resistance R11 of the other secondary battery 11 is 10 milliohms, the cell current I11 is 10 amperes.
Thus, when the internal resistance of the secondary battery 11 is the same, the secondary battery 11 having a battery cell with a small charging rate (a battery cell with a small cell open voltage) is charged by charging in the constant voltage mode. More current flows than the secondary battery 11 having a battery cell with a large rate (battery cell with a large cell open-circuit voltage), and the difference in charge rate is reduced. Therefore, when the power storage system 10 performs charging in the constant voltage mode, variation in the charging rate between the batteries can be reduced.

FIG. 6 is an explanatory diagram illustrating an example of a current flowing through the secondary battery 11 when charging is performed in a command follow-up mode (a mode in accordance with a charge / discharge command from the charge / discharge command device 20). In the example of the figure, a secondary battery 11a having a large internal resistance and a secondary battery 11b having a small internal resistance are shown.
In general, the smaller the resistance, the easier the current flows, and even in the command follow-up mode, the current in the column with the low resistance (the column including the secondary battery 11b) increases. If the command follow-up mode is continued until full charge, the row with the smaller resistance is fully charged first, and the other rows are charged without reaching full charge. In the example of FIG. 6, the charging rate of the column including the secondary battery 11b has reached the upper limit of 90% (%), whereas the charging rate of the column including only the secondary battery 11a remains at 85%.
As described above, as a result of the variation in the charging rate, charging and discharging cannot be performed sufficiently, and there is a possibility that the power fluctuation of the power system 9 cannot be sufficiently handled.

FIG. 7 is an explanatory diagram illustrating an example of a current flowing through the secondary battery 11 when charging is performed by switching from the command following mode to the constant voltage mode (a mode in which the DC voltage of the inverter 12 is constant). As in the case of FIG. 6, in the example of FIG. 7, a secondary battery 11a having a large internal resistance and a secondary battery 11b having a low internal resistance are shown.
In general, the larger the charging rate (SOC), the higher the cell open voltage. When the command tracking mode is switched to the constant voltage mode, the column with a small resistance (the column including the secondary battery 11b) has a large current and a high charging rate in the command tracking mode (88% in the example of FIG. 7). The cell open voltage is high. As a result, the current flowing through the low resistance column is reduced, and the progress of charging is delayed.
On the other hand, a column with a small resistance (a column including the secondary battery 11b) has a small current and a low charging rate in the command following mode (86% in the example of FIG. 7) and a low cell open voltage. As a result, the current flowing through the column having a large resistance increases, and the progress of charging becomes faster.

  In this way, by switching from the command following mode to the constant voltage mode, the current flowing through the secondary battery 11 having a low charging rate increases, and the variation in charging rate is reduced. In particular, it is possible to reduce the current flowing through a cell having a low internal resistance (secondary battery 11b in the example of FIG. 7) and delay the charge rate of the cell from reaching the upper limit. Thereby, when the charging rate of the cell having a small internal resistance reaches the upper limit, the charging rate of the cell having a large internal resistance (secondary battery 11a in the example of FIG. 7) can also approach the upper limit.

FIG. 8 is an explanatory diagram illustrating an example of a processing procedure in which the charge / discharge control device 13 selects a charge / discharge mode.
In step S <b> 111, the charge / discharge switching determination unit 132 determines whether an operation command is received from the charge / discharge command device 20. When it determines with having received the driving | operation command (step S111: Yes), it progresses to step S112. On the other hand, when it determines with not having received the driving | operation command (step S111: No), the stop of an electrical storage system is selected as an operation mode (step S151). When the stop of the power storage system is selected, the charge / discharge control device 13 stops the inverter 12. Thereby, the electrical storage system 10 stops charging / discharging, and stops inputting / outputting electric power.

  In step S <b> 112, the charge / discharge switching determination unit 132 determines whether a charge command is received from the charge / discharge command device 20. When it determines with having received charge instruction (step S112: Yes), it progresses to step S113. On the other hand, when it determines with having not received the charge command (it has received the discharge command) (step S112: No), it progresses to step S131.

  In step S113, the charging rate determination unit 133 determines whether the charging rates of all the secondary batteries 11 are less than the charging rate upper limit value A. When it is determined that the charging rates of all the secondary batteries 11 are less than the charging rate upper limit value A (step S113: Yes), the process proceeds to step S114. On the other hand, when it is determined that there is a secondary battery 11 having a charging rate equal to or higher than the charging rate upper limit value A (step S113: No), stop of the power storage system is selected as the operation mode (step S151).

  In step S114, the charging rate determination unit 133 determines whether or not the charging rates of all the secondary batteries 11 are less than the charging mode switching threshold B. When it is determined that the charging rates of all the secondary batteries 11 are less than the charging mode switching threshold B (step S114: Yes), the command follow-up mode is selected as the operation mode (step S115). On the other hand, when it is determined that there is a secondary battery 11 having a charging rate equal to or higher than the charging mode switching threshold B (step S114: No), the process proceeds to step S121.

  In step S121, the charging rate determination unit 133 determines whether or not the charging power in the constant voltage mode is larger than the charging command value. When it is determined that the charging power in the constant voltage mode is larger than the charging command value (step S121: Yes), the command follow-up mode is selected as the operation mode (step S115). In this case, if the constant voltage mode is set, the charging power exceeds the charging command value. On the other hand, when it is determined that the charging power in the constant voltage mode is equal to or less than the charging command value (step S121: No), the constant voltage mode is selected as the operation mode.

  In step S131, the charging rate determination unit 133 determines whether the charging rates of all the secondary batteries 11 are greater than the charging rate lower limit value D. When it is determined that the charging rates of all the secondary batteries 11 are greater than the charging rate lower limit D (step S131: Yes), the process proceeds to step S132. On the other hand, when it is determined that there is the secondary battery 11 having a charging rate equal to or lower than the charging rate lower limit value D (step S131: No), stop of the power storage system is selected as the operation mode (step S151).

  In step S132, the charging rate determination unit 133 determines whether or not the charging rates of all the secondary batteries 11 are greater than the discharge mode switching threshold C. When it determines with the charge rate of all the secondary batteries 11 being larger than the discharge mode switching threshold C (step S132: Yes), command follow-up mode is selected as an operation mode (step S133). On the other hand, when it is determined that there is a secondary battery 11 having a charging rate equal to or less than the discharge mode switching threshold C (step S132: No), the process proceeds to step S141.

  In step S141, the charging rate determination unit 133 determines whether or not the discharge power in the constant voltage mode is greater than the discharge command value. When it is determined that the discharge power in the constant voltage mode is larger than the discharge command value (step S141: Yes), the command follow-up mode is selected as the operation mode (step S133). In this case, the discharge power exceeds the discharge command value when the constant voltage mode is set. On the other hand, when it is determined that the discharge power in the constant voltage mode is equal to or less than the discharge command value (step S141: No), the constant voltage mode is selected as the operation mode.

Next, with reference to FIG. 9, the rate limiter setting to the charging / discharging which the charging / discharging control apparatus 13 performs is demonstrated.
FIG. 9 is an explanatory diagram illustrating an example of a processing procedure in which the rate control unit 136 sets the necessity of the rate limiter and the rate limiter value. When the charge / discharge switching determination unit 132 detects switching of charge / discharge, the rate control unit 136 performs the process of FIG.

  In step S <b> 211, the communication unit 131 acquires state information of the power system 9. For example, the rate control unit 136 acquires the state information of the power system 9 by inquiring the EMS (Energy Management System) that manages the power system 9 via the communication unit 131 about the state of the power system 9. To do. After step S211, the process proceeds to step S212.

  In step S212, the rate control unit 136 reads information corresponding to the state information obtained in step S211 from the rate limiter storage unit 137, and determines whether the rate limiter is necessary. If it is determined that the rate limiter is necessary (step S212: Yes), the process proceeds to step S213. On the other hand, if it is determined that the rate limiter is not required, the rate limiter is set not to be used (step S215). In this case, the rate control unit 136 outputs the charge / discharge command output from the command tracking control unit 134 or the constant voltage control unit 135 to the communication unit 131 as it is.

  In step S213, the rate control unit 136 sets a limiter rate (set value of the rate limiter) based on the data read from the rate limiter storage unit 137 in step S212, and sets to use the rate limiter (step S214). . In this case, the rate control unit 136 limits the amount of change with respect to the charge / discharge command output from the command follow-up control unit 134 or the constant voltage control unit 135 for a predetermined time (for example, 5 seconds).

  As described above, when it is determined that the charging rates of all the secondary batteries 11 acquired by the communication unit 131 are within the predetermined charging rate range, the command tracking control unit 134 sets the current indicated by the charge / discharge command to the second level. The inverter 12 is controlled to output from the secondary battery 11. On the other hand, when it is determined that the charging rate of the secondary battery acquired by the communication unit 131 exceeds the predetermined charging rate range, the constant voltage control unit 135 applies the predetermined voltage to the secondary battery 11. The inverter 12 is controlled to apply.

Thereby, as demonstrated with reference to FIGS. 5-7, in the electrical storage system 10, the dispersion | variation in the charging rate between the secondary batteries 11 can be reduced, and charge / discharge amount can be enlarged. In particular, even when the number of secondary batteries 11 is large according to large-scale solar power generation or large-scale wind power plant, the power storage system 10 reduces the charge rate variation between the secondary batteries 11 to reduce the charge / discharge amount. Can be bigger. In this respect, the power storage system 10 is compatible with large-scale solar power generation and large-scale wind power plants.
Moreover, the charge / discharge control apparatus 13 should just instruct | command charge / discharge with respect to the inverter 12, and does not need to control charging / discharging of each secondary battery 11. FIG. In this respect, the load on the charge / discharge control device 13 is small.
Thus, according to the electrical storage system 10, the load of the charge / discharge control device 13 is relatively small, and can be applied to large-scale solar power generation and large-scale wind power plants.

Further, the charge / discharge switching determination unit 132 determines whether or not the charge / discharge command for the secondary battery 11 is switched from charge to discharge or from discharge to charge. When it is determined that the charge / discharge command from the charge / discharge command apparatus 20 has been switched, the rate controller 136 causes the inverter 12 to change the rate of change of the charge / discharge current within a predetermined rate of change. The charging / discharging of the secondary battery 11 is controlled.
On the other hand, when it is determined that the charge / discharge command has not been switched, the command follow-up control unit 134 controls the inverter 12 to output the current indicated by the charge / discharge command from the secondary battery 11.

Thereby, it is possible to prevent the system abnormality detection system of the inverter 12 from operating and stopping the output due to the influence of the fluctuation of the charge / discharge of the power storage system 10 on the system voltage.
Here, when the scale of the power storage system 10 is large, a change in power input or output by the power storage system 10 has a great influence on the system voltage (voltage of the power system 9 (FIG. 1)). In particular, when charging / discharging of the power storage system 10 is switched, since the input and output of power are switched, the fluctuation range becomes large. For example, when the charge / discharge command transmitted from the charge / discharge control device 13 to the inverter 12 is switched from charge to discharge or from discharge to charge due to the sudden change in output of the large-scale natural energy power generation facility 912 (FIG. 1), Anomaly detection system may operate. When the system abnormality detection system operates and the output from the inverter 12 is stopped, the response (smoothing) to the power fluctuation of the power system 9 is delayed.

On the other hand, the charge / discharge control device 13 limits the current fluctuation at the time of charge / discharge switching, thereby preventing the operation of the system abnormality detection system and thereby responding to the power fluctuation of the power system 9 (smoothing). Can be prevented.
Moreover, the charge / discharge control apparatus 13 should just instruct | command charge / discharge with respect to the inverter 12, and does not need to control charging / discharging of each secondary battery 11. FIG. In this respect, the load on the charge / discharge control device 13 is small.
Thus, according to the electrical storage system 10, the load of the charge / discharge control device 13 is relatively small, and can be applied to large-scale solar power generation and large-scale wind power plants.

Moreover, in the charge / discharge command apparatus 20 (FIG. 1), the difference calculation part 203 calculates the difference of each charge / discharge measured value of the electrical storage system 10, and a charge / discharge command value. Then, the correction unit 205 performs the charge / discharge measurement value and charge / discharge of the entire power storage system with respect to the charge / discharge command value of the power storage system 10 in which the magnitude of the difference between the charge / discharge measurement value and the charge / discharge command value is a predetermined threshold value or less. Correction is performed to reduce the difference from the command value.
Thereby, the charging / discharging instruction | command apparatus 20 can correct | amend the difference of a discharge measured value and charging / discharging instruction | command value using the electrical storage system 10 considered that tracking to an instruction | command value is favorable, and correct | amends accurately. be able to.

A program for realizing all or part of the functions of the charge / discharge control device 13 and the charge / discharge command device 20 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is stored in a computer system. The processing of each unit may be performed by reading and executing. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Power storage equipment 10 Power storage system 11 Secondary battery 12 Inverter 13 Charge / discharge control apparatus 131 Communication part 132 Charge / discharge switching determination part 133 Charge rate determination part 134 Command follow-up control part 135 Constant voltage control part 136 Rate control part 137 Rate limiter memory | storage part 20 Charge / Discharge Command Device 201 Communication Unit 202 Charge / Discharge Command Generating Unit 203 Difference Calculation Unit 204 Difference Determination Unit 205 Correction Unit

Claims (9)

A charge / discharge control device for controlling charge / discharge of a plurality of secondary batteries connected in parallel to an inverter,
A charge rate acquisition unit for acquiring a charge rate of each of the secondary batteries;
A charging rate determination unit that determines whether or not the charging rates of all the secondary batteries acquired by the charging rate acquisition unit are within a predetermined charging rate range; and
When the charging rate of all the secondary batteries acquired by the charging rate acquisition unit is determined to be within a predetermined charging rate range, the inverter is controlled to output the current indicated by the charge / discharge command from the secondary battery. A command follow-up control unit,
When it is determined that some of the charging rates of the secondary battery acquired by the charging rate acquisition unit exceed the charging rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. A charge / discharge control apparatus comprising: a voltage control unit. A charge / discharge control device for controlling charge / discharge of a secondary battery connected to an inverter,
A charge / discharge switching determination unit for determining whether a charge / discharge command for the secondary battery is switched from charge to discharge or from discharge to charge;
When it is determined by the charge / discharge switching determination unit that the charge / discharge command has been switched, the charge / discharge of the secondary battery by the inverter is performed such that the change rate of the charge / discharge current is within a predetermined change rate range. A rate control unit for controlling
And a command follow-up control unit that controls the inverter to output the current indicated by the charge / discharge command from the secondary battery when the charge / discharge switching determination unit determines that the charge / discharge command has not been switched. Discharge control device. An inverter; a plurality of secondary batteries connected in parallel to the inverter; and a charge / discharge control device for controlling charge / discharge of the plurality of secondary batteries,
The charge / discharge control device comprises:
A charge rate acquisition unit for acquiring a charge rate of each of the secondary batteries;
A charging rate determination unit that determines whether or not the charging rates of all the secondary batteries acquired by the charging rate acquisition unit are within a predetermined charging rate range; and
When the charging rate of all the secondary batteries acquired by the charging rate acquisition unit is determined to be within a predetermined charging rate range, the inverter is controlled to output the current indicated by the charge / discharge command from the secondary battery. A command follow-up control unit,
When it is determined that some of the charging rates of the secondary battery acquired by the charging rate acquisition unit exceed the charging rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. A voltage controller;
A power storage system comprising: An inverter, a secondary battery connected to the inverter, and a charge / discharge control device for controlling charge / discharge of the secondary battery,
The charge / discharge control device comprises:
A charge / discharge switching determination unit for determining whether a charge / discharge command for the secondary battery is switched from charge to discharge or from discharge to charge;
When it is determined by the charge / discharge switching determination unit that the charge / discharge command has been switched, the charge / discharge of the secondary battery by the inverter is performed such that the change rate of the charge / discharge current is within a predetermined change rate range. A rate control unit for controlling
When it is determined that the charge / discharge command is not switched by the charge / discharge switching determination unit, a command tracking control unit that controls the inverter to output the current indicated by the charge / discharge command from the secondary battery;
A power storage system comprising: A charge / discharge command apparatus that commands charge / discharge to a plurality of the power storage systems according to claim 3 or claim 4,
A charge / discharge measurement value acquisition unit for acquiring each charge / discharge measurement value of the power storage system;
A difference calculation unit for calculating a difference between the charge / discharge measurement value and the charge / discharge command value;
The difference between the charge / discharge measured value and the charge / discharge command value of the entire power storage system is reduced with respect to the charge / discharge command value of the power storage system in which the difference between the charge / discharge measured value and the charge / discharge command value is a predetermined threshold value or less. A correction unit for performing correction, and
A charge / discharge command apparatus comprising: A charge / discharge control method for controlling charge / discharge of a plurality of secondary batteries connected in parallel to an inverter,
A charge rate acquisition step of acquiring a charge rate of each of the secondary batteries;
A charging rate determination step for determining whether or not the charging rates of all the secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range; and
When it is determined that the charging rates of all the secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range, the inverter is configured to output the current indicated by the charge / discharge command from the secondary battery. Command follow control step to control;
When it is determined that there is a charge rate of the secondary battery acquired in the charge rate acquisition step that exceeds the charge rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. A charge / discharge control method comprising: a constant voltage control step. A charge / discharge control method for controlling charge / discharge of a secondary battery connected to an inverter,
Charge / discharge switching determination step for determining whether or not the charge / discharge command for the secondary battery has been switched from charge to discharge or from discharge to charge;
When it is determined that the charge / discharge command has been switched in the charge / discharge switching determination step, the charging / discharging of the secondary battery by the inverter is performed so that the change rate of the charge / discharge current is within a predetermined change rate range. A rate control step for controlling the discharge;
A command follow-up control step for controlling the inverter to output the current indicated by the charge / discharge command from the secondary battery when it is determined in the charge / discharge switching determination step that the charge / discharge command is not switched. Discharge control method. To a computer that controls charging / discharging of a plurality of secondary batteries connected in parallel to an inverter,
A charge rate acquisition step of acquiring a charge rate of each of the secondary batteries;
A charging rate determination step for determining whether or not the charging rates of all the secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range; and
When it is determined that the charging rates of all the secondary batteries acquired in the charging rate acquisition step are within a predetermined charging rate range, the inverter is configured to output the current indicated by the charge / discharge command from the secondary battery. Command follow control step to control;
When it is determined that there is a charge rate of the secondary battery acquired in the charge rate acquisition step that exceeds the charge rate range, the inverter is controlled to apply a predetermined voltage to the secondary battery. A program for executing the constant voltage control step. To the computer that controls the charge and discharge of the secondary battery connected to the inverter,
Charge / discharge switching determination step for determining whether or not the charge / discharge command for the secondary battery has been switched from charge to discharge or from discharge to charge;
When it is determined that the charge / discharge command has been switched in the charge / discharge switching determination step, the charging / discharging of the secondary battery by the inverter is performed so that the change rate of the charge / discharge current is within a predetermined change rate range. A rate control step for controlling the discharge;
When it is determined that the charge / discharge command is not switched in the charge / discharge switching determination step, a command follow-up control step for controlling the inverter to output the current indicated by the charge / discharge command from the secondary battery is executed. Program for.

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