JP2015077012A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of efficiently operating a power storage medium by avoiding an increase in internal resistance of the power storage medium due to a temperature decrease and a decrease in the capacity of the power storage medium without using an air conditioner and a heater, and the like.SOLUTION: A power storage device comprises: an inverter INV connected to a system; a smoothing capacitor C1 connected to a DC side of the inverter INV; a power storage medium 2 having an internal resistance; a DC/DC chopper 1 connected between the smoothing capacitor C1 and the power storage medium 2; and a control device 4 which controls operation of the DC/DC chopper 1. The inverter INV performs smoothing capacitor voltage constant control. When a temperature of the power storage medium 2 becomes lower than or equal to a predetermined setting value, the control device 4 repeats charge and discharge between the smoothing capacitor C1 and the power storage medium 2 by increasing and decreasing the output voltage of the DC/DC chopper 1.

Description

  The present invention relates to a temperature compensation technique for a power storage medium installed in a voltage compensation device for a system, a device for adjusting a power amount of the system by charging and discharging, and stabilizing the system.

  Patent Document 1 discloses a voltage sag compensator using an electric double layer capacitor as a power storage medium. As shown in FIG. 13, Patent Document 1 charges a capacitor with a voltage setting value that satisfies the compensation time of the short-time rated specification according to the temperature detection value of the electric double layer capacitor.

JP 2008-29064 A

   It is known that the internal resistance of a power storage medium (for example, an electric double layer capacitor) increases as the temperature decreases. For this reason, in order to efficiently extract the energy stored in the power storage medium, it is necessary to reduce the internal resistance as much as possible. For this reason, the ambient temperature of the power storage medium is often adjusted using an air conditioner, a heater, or the like.

  However, when the temperature of the power storage medium is increased by an air conditioner, a heater, or the like, the power storage medium is heated by increasing the ambient temperature, and thus there is a loss due to the fact that the power storage medium is not directly warmed. There is also a problem that the amount of heater needs to be adjusted depending on the installation environment. In addition, the installation of air conditioners, heaters, and the like has also caused problems such as increased device costs and increased installation space.

  As described above, in a power storage device using a power storage medium, without using an air conditioner, a heater, or the like, an increase in internal resistance and a decrease in capacity of the power storage medium due to a temperature drop can be avoided, and the power storage medium can be efficiently It becomes a problem to operate.

  The present invention has been devised in view of the conventional problems, and one aspect thereof is an inverter connected to the system, a smoothing capacitor connected to the DC side of the inverter, and a storage medium having an internal resistance. A power storage device comprising: a DC / DC chopper connected between the smoothing capacitor and the power storage medium; and a control device for controlling the operation of the DC / DC chopper. The control device repeats charging and discharging between the smoothing capacitor and the power storage medium by raising and lowering the output voltage of the DC / DC chopper when the temperature of the power storage medium falls below a preset set value. It is characterized by making it.

  In another aspect, the power storage device includes an inverter connected to a system, a power storage medium connected to a DC side of the inverter, and a control device that controls the operation of the inverter, the control device Is the amount of discharge when the system voltage is high when the temperature of the power storage medium falls below a preset value, and the output voltage of the inverter is increased and decreased to repeatedly charge and discharge between the system and the power storage medium. Is characterized in that the discharged energy is the amount consumed by the switching loss of the inverter.

  According to the present invention, in a power storage device using a power storage medium, without using an air conditioner or a heater, the increase in the internal resistance and capacity of the power storage medium due to a temperature drop is avoided, and the power storage medium is operated efficiently. It becomes possible to do.

1 is a block diagram illustrating a power storage device in Embodiment 1. FIG. 3 is a flowchart illustrating a charge / discharge operation of the power storage device according to the first embodiment. 3 is a time chart illustrating a charge / discharge operation of the power storage device according to the first embodiment. The block diagram which shows the state of the electrical storage apparatus in the normal time. The block diagram which shows the state of the electrical storage apparatus at the time of low temperature. FIG. 6 is a block diagram illustrating a power storage device in Embodiment 2. The block diagram which shows the state of the electrical storage apparatus in the normal time. The block diagram which shows the state of the electrical storage apparatus at the time of voltage compensation and an electric power shortage. The block diagram which shows the state of the electrical storage apparatus after voltage compensation and at the time of system | strain surplus electric power. 9 is a flowchart showing a charge / discharge operation of the power storage device according to the second embodiment. The block diagram which shows the state of the electrical storage apparatus at the time of low temperature. The block diagram which shows the state of the electrical storage apparatus at the time of low temperature (when the discharge to a system | strain is impossible). Schematic which shows an example of the conventional sag compensation apparatus.

   Hereinafter, Embodiments 1 and 2 of a power storage device according to the present invention will be described in detail with reference to FIGS.

[Embodiment 1]
FIG. 1 is a block diagram illustrating the power storage device according to the first embodiment. As shown in FIG. 1, the power storage device includes an inverter INV, a smoothing capacitor C1, a DC / DC chopper 1, a power storage medium 2, a temperature sensor 3 that detects the temperature of the power storage medium 2, a control device 4, It has.

  The inverter INV is connected to the system and performs constant smoothing capacitor voltage control. When the voltage of the smoothing capacitor C1 is low, the AC voltage of the system is converted into a DC voltage and supplied to the smoothing capacitor C1, and the smoothing capacitor C1 is charged. On the other hand, when the smoothing capacitor voltage is high, the DC voltage of the smoothing capacitor C1 is converted into an AC voltage and supplied to the system.

  The smoothing capacitor C1 smoothes the DC voltage converted from the AC voltage of the system.

  The DC / DC chopper 1 is configured using a coil, a transistor, and a capacitor (not shown). The DC / DC chopper 1 has a function of stepping up and down DC voltage using a coil or the like. For example, the current that flows in accordance with the switching operation of the transistor is stored as electromagnetic energy in the coil, and further, the electromagnetic energy is stored in a capacitor to increase the voltage. Since the DC / DC chopper 1 is well known, a detailed description thereof will be omitted.

  The power storage medium 2 is, for example, an electric double layer capacitor, and is a large capacity capacitor that can charge and discharge a large capacity instantaneously.

  The control device 4 includes a voltage monitoring unit 4a that monitors the system voltage, a temperature sensing unit 4c that compares the temperature of the power storage medium 2 detected by the temperature sensor 3 with a preset temperature, and a temperature sensing unit 4c. And a charge / discharge signal output unit 4b for outputting a charge / discharge signal to the DC / DC chopper 1 based on the comparison result.

  The said electrical storage apparatus adjusts the electric energy of a system | strain by charging / discharging, and stabilizes a system | strain. Next, the operation of the charge / discharge operation will be described in detail based on the flowchart of FIG. 2, the time chart of FIG. 3, and the block diagrams of FIGS.

  First, in S1, the temperature sensing unit 4c determines whether or not the temperature of the power storage medium 2 is lower than a set temperature. When the temperature of the electric storage medium 2 is equal to or higher than the set temperature, as shown in FIG. 4, the operation of the DC / DC chopper 1 is stopped, charging / discharging is not performed between the smoothing capacitor C1 and the electric storage medium 2, and the standby state And

  When the temperature of the power storage medium 2 is lower than the set temperature, a charge / discharge signal is output from the charge / discharge signal output unit 4b to the DC / DC chopper 1 in S2, and the DC / DC chopper 1 is operated. As shown in FIGS. 3 and 5, charging / discharging is repeatedly performed between the smoothing capacitor C <b> 1 and the power storage medium 2 by the switching operation of the DC / DC chopper 1, and the temperature of the power storage medium 2 is increased by the internal resistance of the power storage medium 2. Let

  In S3, the temperature sensing unit 4c determines whether or not the temperature of the power storage medium 2 is higher than the set temperature. When the temperature of the power storage medium 2 is equal to or lower than the set temperature, the process returns to S2, and charging / discharging is performed again between the smoothing capacitor C1 and the power storage medium 2.

  When it is determined in S3 that the temperature of the power storage medium 2 is higher than the set temperature, the DC / DC chopper 1 is stopped. Thus, the state where the power storage medium 2 is equal to or lower than the set temperature can be avoided by the processes of S1 to S4.

  Here, the average voltage of the smoothing capacitor C1 and the power storage medium 2 is made constant. When the current i is passed through the smoothing capacitor C1, the voltage change is expressed by the following equation (1). In order to make the average voltage constant, it is necessary to make the following equation (2), which is the current increase due to the charging current, and the following equation (3), which is the voltage decrease due to the discharge current.

  For example, if the charge time and the discharge time are the same value, the charge / discharge current command value having the same current value may be used.

   In the first embodiment, the electric storage medium 2 such as an electric double layer capacitor uses a characteristic that the deterioration due to charging / discharging is small, and the DC / DC chopper 1 performs minute charging / discharging between the smoothing capacitor C1 and the electric storage medium 2. By repeating, the temperature of the power storage medium 2 body is increased by the internal resistance of the power storage medium 2.

   According to the power storage device in the first embodiment, an increase in internal resistance of the power storage medium 2 due to a temperature decrease is avoided, and a decrease in the capacity of the power storage medium 2 is avoided, so that the power storage medium 2 can be operated efficiently. .

  Further, there is no need to change the conventional circuit system. Furthermore, since it is not necessary to install an air conditioner, a heater, or the like, it is possible to suppress an increase in cost of the apparatus and an increase in installation space.

   Further, loss (switching loss, loss due to internal resistance) is generated by operating the DC / DC chopper 1 and flowing an average current of zero through the smoothing capacitor C1 and the power storage medium 2. If the inverter INV is stopped, the DC voltage of the smoothing capacitor C1 and the power storage medium 2 is lowered by repeating charging and discharging for a long time. However, since the inverter INV performs constant capacitor voltage control, the loss is replenished and no voltage drop occurs in the smoothing capacitor C1. This operation is an operation that is always performed in the voltage sag compensator.

   Further, in the above operation, the smoothing capacitor voltage increases or decreases when the current increase ΔV due to the charging current of the equation (2) or the current decrease ΔV due to the discharge current of the equation (3) is large. Even in such a case, since the inverter INV performs constant control of the smoothing capacitor voltage, the current flows into the system when the current increase ΔV due to the charging current is large, and the system when the current decrease ΔV due to the discharge current is large. Current will flow out of the.

[Embodiment 2]
Next, the power storage device in Embodiment 2 will be described. Hereinafter, description of the same parts as those in the first embodiment will be omitted, and only differences from the first embodiment will be described. As illustrated in FIG. 6, the power storage device according to the second embodiment includes an inverter INV, a power storage medium 2, a temperature sensor 3, and a control device 4. When an instantaneous voltage drop or instantaneous power failure occurs in the system, instantaneous voltage drop compensation is performed by supplying electric energy stored in the storage medium 2 to the system via the inverter INV.

  During normal operation, as shown in FIG. 7, the inverter INV is stopped and the power storage medium 2 is not charged / discharged, and is set in a standby state.

  When voltage compensation is performed on the system, or when power is insufficient in the system, the inverter INV is operated to discharge the power storage medium 2 as shown in FIG.

  After voltage compensation or at the time of system surplus power, as shown in FIG. 9, the inverter INV is operated to charge the power storage medium 2.

  Next, the charge / discharge operation will be described with reference to FIGS. 10, 11, and 12.

  First, in S11, the temperature sensing unit 4c determines whether or not the temperature of the power storage medium 2 is lower than the set temperature. When the temperature of the power storage medium 2 is equal to or higher than the set temperature, the inverter INV is stopped and the power storage medium 2 is not charged / discharged, as shown in FIG.

  When the temperature of the power storage medium 2 is lower than the set temperature, in S12, a charge / discharge signal is output from the charge / discharge signal output unit 4b to the inverter INV to operate the inverter INV. As shown in FIG. 11, charging and discharging are repeatedly performed between the system and the power storage medium 2 by the operation of the inverter INV, and the temperature is increased by the internal resistance of the power storage medium 2.

  Next, in S13, the voltage monitoring unit 4a determines whether or not the system voltage is rising. If the system voltage is higher than a preset threshold value, the process proceeds to S14, and if the system voltage is equal to or less than the threshold value, the process proceeds to S15.

  In S14, as shown in FIG. 12, the charge / discharge signal from the charge / discharge signal output unit 4b is switched to reduce the discharge capacity. At this time, the amount of discharge from the power storage medium 2 is set such that the discharged energy is consumed only by the switching loss of the inverter INV and is not discharged to the system.

  In S15, the temperature sensing unit 4c determines whether or not the temperature of the power storage medium 2 is higher than the set temperature. When the temperature of the power storage medium 2 is equal to or lower than the set temperature, the process returns to S12, and charging / discharging is performed again between the system and the power storage medium 2.

  If it is determined in S15 that the temperature of the power storage medium 2 is higher than the set value, the inverter INV is stopped. In this way, it is possible to avoid a state where the power storage medium 2 is lower than the set temperature.

  As described above, according to the second embodiment, the same operational effects as those of the first embodiment can be obtained.

  Further, when the system voltage is high, it is possible to suppress the system voltage from rising by setting the discharge amount to the amount of only the switching loss.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

  For example, in the embodiment, the electric double layer capacitor is exemplified as the power storage medium 2, but a secondary battery or the like may be used.

INV ... Inverter C1 ... Smoothing capacitor 1 ... DC / DC chopper 2 ... Power storage medium 4 ... Control device

Claims (2)

An inverter connected to the grid;
A smoothing capacitor connected to the DC side of the inverter;
A power storage medium having internal resistance;
A DC / DC chopper connected between the smoothing capacitor and the storage medium;
A power storage device comprising a control device for controlling the operation of the DC / DC chopper,
The inverter performs smoothing capacitor voltage constant control,
When the temperature of the power storage medium is equal to or lower than a preset value, the control device increases or decreases the output voltage of the DC / DC chopper and repeats charging / discharging between the smoothing capacitor and the power storage medium. A power storage device. An inverter connected to the grid;
A storage medium connected to the DC side of the inverter;
A control device for controlling the operation of the inverter, and a power storage device comprising:
When the temperature of the power storage medium falls below a preset value, the control device increases and decreases the output voltage of the inverter, repeats charging and discharging between the system and the power storage medium, and when the system voltage is high The amount of discharge of is an amount that the discharged energy is consumed by the switching loss of the inverter.

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