JP2011239543A - Instantaneous voltage drop compensation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instantaneous voltage drop compensation device that can surely determine the quality of the operation of a converter.SOLUTION: An instantaneous voltage drop compensation device includes: a switching part 3 that outputs AC power that is provided from a power supply 1 to a load 2; a converter 4 that converts AC power supplied from the power supply 1 or from the switching part 3 to DC power; a power storage part 7 that is subjected to power storage by DC power of this converter 4; and a control part 8 that controls the converter 4 so that, when AC voltage supplied from the power supply 1 to the switching part 3 dropped or shut off, the switching part 3 is blocked and, at the same time, DC power from the power storage part 7 is converted to AC power to be output to the load 2. There is provided a determination part 12 that determines the quality of the operation of the converter 4 by at least either one of a charging current or a charging voltage of the converter 4 when a storage voltage of the power storage part 7 is equal to or lower than a setting value.

Description

  The present invention relates to an instantaneous voltage drop (instantaneous voltage drop) compensation device that compensates for a voltage when a power supply voltage drops instantaneously or causes a power failure so that power supply to a load is not affected.

  In recent years, in an important load facility such as a production facility, a voltage sag compensator has been introduced in order to prevent a power supply voltage from being instantaneously reduced or a power failure due to a lightning strike or the like, resulting in a failure in the operation of the facility.

  An example of the voltage sag compensator is shown in FIG. As shown in FIG. 3, this voltage sag compensator includes an AC switch (a thyristor connected in reverse parallel) 3 connected between an input (system power supply) 1 and an output (load) 2, an inverter and a chopper (DC -DC converter) each having a first converter 5 and a second converter 6 and a power storage unit 7 (for example, an electric double layer capacitor). A control unit 8 including a control power supply 9 and a control circuit 10 is connected between the first converter 5 and the second converter 6.

  In a steady state, the AC switch 3 is alternately turned on (on) to supply AC power from the system power supply 1 to the load 2. Further, when a voltage drop or a power failure (hereinafter referred to as a momentary voltage drop) occurs instantaneously in the AC power from the system power supply 1 due to a lightning strike or the like, the AC switch 3 is shut off (turned off) by the control of the control circuit 10. Electric power at the time of a sag is obtained by boosting the storage voltage (DC voltage) of the storage unit 7 with a chopper (DC-DC converter) of the conversion unit 4 and further converting it into an AC voltage with an inverter and supplying AC power to the load 2. The supply is compensated (see, for example, Patent Document 1).

JP 2002-10528 A

  By the way, in the above sag compensation device, the AC power from the system power supply 1 is supplied to the load 2 via the AC switch 3, and at the same time, the chopper and the inverter of the conversion unit 4 are always operated as a converter, and the first converter The voltage (intermediate voltage) between 5 and the second converter 6 and the stored voltage of the power storage unit 7 are maintained at a constant voltage. In such a voltage sag compensator, a semiconductor element is normally used for the chopper or inverter of the converter 4, and in order to ensure the operation of the device at the time of voltage sag, the chopper or inverter of the converter 4 It is desirable to monitor whether the operation is normal (whether the semiconductor element is normal).

  Conventionally, whether the operation of the chopper or inverter of the conversion unit 4 is good or bad is determined whether the difference between the preset set value and the charging current or charging voltage flowing through the chopper or inverter of the conversion unit 4 is within an allowable range. This has been done by the chopper of the converter 4 and the inverter itself judging. However, in the steady state, as shown above, the intermediate voltage and the storage voltage of the power storage unit 7 are maintained at a substantially constant voltage, so that the charging current or the charging voltage flowing through the chopper or inverter of the conversion unit 4 is small. Thus, it is difficult to determine whether there is a difference between a preset setting value and a charging current or a charging voltage, and whether the difference is within an allowable range.

  Accordingly, an object of the present invention is to provide a voltage sag compensator that can solve the above-described difficulties and reliably determine whether the operation of the converter is good or bad.

  In order to solve the above problems, the voltage sag compensator of the present invention includes a switching unit 3 that is supplied with AC power from the power source 1 and outputs AC power to the load 2 side, and AC power supplied from the power source 1 or the switching. The conversion unit 4 that converts the AC power from the unit 3 into DC power, the power storage unit 7 that is stored with the DC power of the conversion unit 4, and the AC power that is supplied from the power source 1 to the switching unit 3 is reduced in voltage. Or, in the event of a power failure, the controller 8 controls the converter 4 so as to shut off the switching unit 3 and convert the DC power from the power storage unit 7 into AC power and output it to the load 2 side. A determination unit 12 is provided that determines whether the operation of the conversion unit 4 is good or not at least one of the charging current and the charging voltage of the conversion unit 4 when the storage voltage of the power storage unit 7 is equal to or lower than a set value.

  According to the voltage sag compensator of the present invention, when the storage voltage of the power storage unit is lower than the set value, that is, when a relatively large charging current or charging voltage is applied to the power storage unit, Since at least one of the charging voltages is provided with a determination unit that determines whether the operation of the conversion unit is good, the charging current or the charging voltage flowing through the conversion unit is relatively large, and is set in advance to determine whether the conversion unit is good or bad The difference between the set value and the charging current or the charging voltage can be easily detected, and the quality of the operation of the conversion unit can be determined with certainty.

It is a circuit diagram showing an embodiment of a voltage sag compensator according to the present invention. It is a circuit diagram which shows different embodiment. It is a circuit diagram which shows the conventional sag compensation apparatus.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a voltage sag compensator according to the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected about the part similar or equivalent to FIG. As shown in FIG. 1, the voltage sag compensator according to the present invention is provided between an input 1 for supplying AC power (hereinafter referred to as a system power supply) and an output 2 for digesting AC power (hereinafter referred to as a load). Connected switching unit 3 (anti-parallel connected thyristor, hereinafter referred to as AC switch), conversion unit 4 connected between AC switch 3 and load 2, and power storage unit 7 connected to this conversion unit 4 (For example, an electric double layer capacitor). The conversion unit 4 includes a first converter 5 and a second converter 6 each having an inverter and a chopper (DC-DC converter).

  A control unit 8 is connected between the first converter 5 and the second converter 6. The connection unit 8 is connected to the control power source 9 connected between the first converter 5 and the second converter 6, and connected to the control power source 9 to switch the AC switch 3 and charge the power storage unit 7. The control circuit 10 is configured to be controlled.

  Furthermore, a voltage detection unit 11 is connected between the power storage unit 7 and the conversion unit 4, and at least one set value of the charging current and the charging voltage set in advance and an actual current value or A determination unit 12 that determines whether the difference from the voltage value is within an allowable range, that is, whether the operation of the conversion unit 4 is good or bad is connected. The voltage detection unit 11 and the determination unit 12 are also connected to the control circuit 10.

  The AC switch 3, the conversion unit 4, the power storage unit 7, the control unit 8, the voltage detection unit 11, and the determination unit 12 constitute a voltage sag compensation device.

  In the steady state, the voltage sag compensator alternately turns on (turns on) the AC switch 3 to supply the AC power from the system power supply 1 to the load 2. The AC switch 3 is shut off (off), and the stored power (DC power) of the power storage unit 7 is converted into AC power via the first converter 5 and the second converter 6 and boosted as necessary. 2 is compensated for by supplying power to 2.

  On the other hand, in charging the power storage unit 7, the voltage detection unit 11 detects the power storage voltage of the power storage unit 7, and the second conversion is performed under the control of the control circuit 10 when the power storage voltage falls below a preset set value. The battery 6 is operated as a converter to convert the AC power from the AC switch 3 into DC power and charge the power storage unit 7. Note that charging of the power storage unit 7 may be performed when the voltage (intermediate voltage) between the first converter 5 and the second converter 6 is equal to or lower than a preset value. You may make it charge the electrical storage part 7, when both an electrical storage voltage and an intermediate voltage are below the preset setting value.

  The power storage unit 7 is charged during a period in which the intermediate voltage and the power storage voltage of the power storage unit 7 have fallen below a preset value due to discharge or spontaneous discharge by voltage compensation operation. It is preferable to control so that there is no.

  Thus, according to the voltage sag compensator of the present invention, since charging is performed in a state where the stored voltage of the power storage unit 7 is reduced below a set value, the charging current flowing through the first converter 5 and the second converter 6 The charging voltage is also relatively large, and it is possible to easily determine a difference from a set value set in advance in the determination unit 12 in order to determine whether the operation of the first converter 5 or the second converter 6 is good. The determination of pass / fail is performed by, for example, determining whether the difference between the set value of at least one of the charging current and the charging voltage and the actual current value or voltage value is within an allowable range by the determination unit 12.

  As shown in FIG. 2, the first converter 5 is connected between the system power supply 1 and the AC switch 3, and AC power supplied to the AC switch 3 (AC power from the system power supply 1) is Control may be performed so that the single converter 5 converts the DC power into DC power and charges the power storage unit 7. In this case, it is possible to determine whether the operation of the first converter 5 is good or bad.

  Further, the charging operation may be performed during a period other than the period in which the intermediate voltage and the storage voltage of the power storage unit 7 are reduced to a preset value or less. In this case, it is possible to periodically reduce the storage voltage to a set value or less (for example, once a month) and determine whether the operation of the first converter 5 or the second converter 6 is good or bad by the method described above. preferable.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, the determination unit 12 may be connected to a display unit, a notification unit, or the like that indicates the quality determination result of the conversion unit 4.

  1 .... System power supply, 2 .... Load, 3 .... AC switch, 4 .... Conversion unit, 7 .... Power storage unit, 8 .... Control unit, 12 .... Determination unit

Claims (1)

  A switching unit 3 that is supplied with AC power from the power source 1 and outputs AC power to the load 2; a converter unit 4 that converts AC power supplied from the power source 1 or AC power from the switching unit 3 into DC power; When the AC power supplied from the power source 1 to the switching unit 3 is reduced or the power is cut off, the switching unit 3 is shut off and the power storage unit is stored. And a control unit 8 that controls the conversion unit 4 so as to convert the DC power from 7 into AC power and output it to the load 2 side, and the conversion is performed when the storage voltage of the storage unit 7 is equal to or lower than a set value. A voltage sag compensator characterized by comprising a determination unit 12 for determining whether or not the operation of the conversion unit 4 is good at least by either the charging current or charging voltage of the unit 4.