JP2012016178A - Momentary voltage drop and power failure compensation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a momentary voltage drop and power failure compensation device which can reduce a capacity of a capacitor part and attempt miniaturization.SOLUTION: A momentary voltage drop and power failure compensation device is configured so that a control part 8 shuts down a switching part 4 while converting direct-current power output from a first conversion part 5 and power stored in a capacitor part 7 into AC power by a second conversion part 6 to output it to the side of a load 3, when a voltage drop of a power supply 2 is lower than a preset value. When the voltage drop of the power supply 2 is higher than the preset value, or in case of power failure, the control part 8 shuts down the switching part 4 and the first conversion part 5 while converting the power stored in the capacitor part 7 into AC power by the second conversion part 6 to output it to the side of the load 3.

Description

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

  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. 2, the voltage sag compensator includes an AC switch 12 (thyristor connected in reverse parallel) connected between an input 10 (system power supply) and an output 11 (load), an inverter and a chopper (DC). -DC converter) and the first converter 13 and the second converter 14, respectively, and a power storage unit 15 (for example, an electric double layer capacitor).

  In a steady state, the AC switch 12 is alternately turned on (turned on) to supply AC power from the system power supply 10 to the load 11. Further, when a voltage drop or a power failure occurs instantaneously in the system power supply 10 due to a lightning strike or the like, the AC switch 12 is cut off (OFF), and the storage voltage (DC voltage) of the storage unit 15 is boosted by a chopper (DC-DC converter). Further, the power supply at the time of a power failure or a power failure is compensated by converting the AC voltage into an AC voltage by an inverter and supplying AC power to the load 11 (see, for example, Patent Document 1).

JP 2002-10528 A

  However, in the voltage sag compensator, the power necessary for voltage compensation is supplied from the power storage unit 15 at the time of voltage sag, so the total power required to drive the load equipment for a certain period of time. The power storage unit 15 must be covered only, and the power storage unit 15 inevitably increases in size, making it difficult to downsize the voltage sag compensator.

  Accordingly, an object of the present invention is to provide a voltage sag / power failure compensation device that solves the above-described problems and can reduce the capacity of the power storage unit and reduce the size thereof.

  In order to solve the above problems, the voltage sag / blackout compensation device 1 of the present invention includes a switching unit 4 that is supplied with AC power from the power source 2 and outputs AC power to the load 3 side, and AC power supplied from the power source 2. The first conversion unit 5 that converts the DC power into the DC power, the second conversion unit 6 that converts the DC power output from the first conversion unit 5 into AC power and outputs the AC power to the load 3 side, and the first A power storage unit 7 that is charged with DC power from one conversion unit 5 or the second conversion unit 6, and a control unit that controls the switching unit 4, the first conversion unit 5, and the second conversion unit 6. 8, and when the voltage drop of the power source 2 is smaller than a preset set value, the control unit 8 shuts off the switching unit 4 and outputs the direct current output from the first conversion unit 5. The electric power and the electric power stored in the electric storage unit 7 are converted into the second conversion unit. When the voltage drop of the power source 2 is larger than the set value or a power failure, the control unit 8 causes the switching unit 4 and the first conversion unit to convert the AC power to the load 3 side. 5 is cut off, and the power stored in the power storage unit 7 is converted into AC power by the second conversion unit 6 and output to the load 3 side.

  According to the voltage sag / power failure compensation device of the present invention, when the voltage drop of the power source is smaller than a preset value, the control unit shuts off the switching unit and outputs the direct current from the first conversion unit. The power and the stored power of the power storage unit are converted into AC power by the second conversion unit and output to the load side, that is, when the voltage drop occurs as in the conventional case, the power supply from the power source is cut off and the power storage The power supply to the load is not performed by the unit alone, but the power supply from the power supply is not cut off if the voltage drop is smaller than a preset value even if the power supply voltage drop occurs in the power supply. Since power is supplied to the converter, and only the shortage of the DC power output from the first converter is compensated by the stored power of the power storage unit, all power necessary for voltage compensation is supplied from only the power storage unit. To supply conventional ones Base, it is possible to reduce the power storage unit to be borne. Therefore, the capacity of the power storage unit can be reduced. As a result, the power storage unit can be reduced in size, and the power supply unit can be reduced in size so that the instantaneous voltage drop / power failure compensation device can be reduced in size. .

  When the voltage drop of the power source is larger than the set value or a power failure, the control unit shuts off the switching unit and the first conversion unit, and the stored power of the power storage unit is changed to AC power by the second conversion unit. Conversion and output to the load side, that is, operation similar to that of the conventional voltage sag compensator is performed, so that the operation of the load facility is not affected.

1 is a circuit diagram showing an embodiment of a voltage sag / power failure compensation device according to the present invention. It is a circuit diagram which shows the conventional sag compensation apparatus.

  Hereinafter, an embodiment of a voltage sag / power failure compensation device 1 according to the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the voltage sag / blackout compensation device 1 of the present invention is supplied with AC power from a system power source 2 (hereinafter referred to as AC power source) and outputs AC power to the load 3 side (reverse) A thyristor connected in parallel: hereinafter referred to as an AC switch), a first converter 5 (converter) for converting AC power supplied from the AC power source 2 into DC power, and a DC output from the first converter 5 A second converter 6 (inverter) that converts electric power into AC power and outputs it to the load 3 side, and a capacitor 7 (for example, an electric double layer) that is charged with DC power from the first converter 5 or the second converter 6 And a control unit 8 that controls the AC switch 4, the first converter 5, and the second converter 6.

  The AC switch 4, the first converter 5, the second converter 6, the capacitor 7, and the control unit 8 are respectively connected as shown in FIG. Specifically, the AC switch 4 is connected between the AC power source 2 and the load 3, the first converter 5 is connected to a power line branched from between the AC power source 2 and the AC switch 4, and the second The converter 6 is connected to the first converter 5 and a power line branched from between the AC switch 4 and the load 3, and the capacitor 7 is branched from between the first converter 5 and the second converter 6. Connected to the power line. In addition, a chopper 9 that boosts the voltage between the first converter 5 and the second converter 6 and connected to the battery 7 is connected to the power line branched from the first converter 5 and the second converter 6. The control unit 8 is connected to the AC switch 4, the first converter 5, the second converter 6, and the chopper 9, respectively.

  In the steady state, the voltage sag / power failure compensation device 1 alternately turns on (turns on) the AC switch 4 to supply AC power from the AC power source 2 to the load 3.

  At this time, the second converter 6 is operated as a converter to convert the AC power supplied from the AC switch 4 into DC power, and this DC power is supplied to the capacitor 7 to store electricity. Note that the first converter 5 may convert the AC power supplied from the AC power supply 2 into DC power, and supply the DC power to the capacitor 7 for storage.

  When a voltage drop or a power failure occurs in the AC power supply 2 due to a lightning strike or the like, both the AC switch 4 and the first converter 5 are shut off once by the control of the control unit 8, and the stored power of the capacitor 7 is supplied to the second converter. 6 is shifted to a power failure mode in which it is converted into AC power and output to the load 3 side, and the voltage drop of the AC power supply 2 is detected in about two cycles immediately after the occurrence of abnormality.

  When the voltage drop is smaller than a preset value, that is, when a corresponding voltage remains in the AC power supply 2, the AC switch 4 is shut off and the first conversion is performed under the control of the control unit 8. The converter 5 is put into an operating state, and the DC power output from the first converter 5 and the stored power of the battery 7 are converted into AC power by the second converter 6 and shifted to the instantaneous voltage drop mode for output to the load 3 side. Compensates for power supply during a sag. The set value for the voltage drop is set to 80%, for example. If the voltage is 20% or more of the steady-state voltage, power is supplied to the load 3 through the first converter 5. However, the set values are merely examples, and can be changed as appropriate in accordance with the usage status of the voltage sag / power failure compensation device 1.

  In this way, immediately after the occurrence of a sag or power failure, the mode immediately shifts to the power failure mode, and power is supplied to the load 3. In the initial period until the setting, it is possible to reliably supply power without a delay in compensation. When the voltage drop is smaller than the preset value, the power energy of the AC power supply 2 whose voltage is lowered is supplied to the load 3 via the first converter 5 and only the shortage due to the voltage drop is supplied. Since it is set as the structure supplied from the electrical storage device 7, consumption of the electrical storage energy of the electrical storage device 7 at the time of a sag can be suppressed.

  On the other hand, if the voltage drop of the AC power supply 2 is larger than the set value or a power failure occurs, no corresponding voltage remains in the AC power supply 2 and the operation of the power failure mode is continued under the control of the control unit 8. . That is, both the AC switch 4 and the first converter 5 (transistors constituting the converter) are shut off, and the stored power of the capacitor 7 is converted into AC power by the second converter 6 and output to the load 3 side. , Compensate for power supply at the time of instantaneous drop or power failure. Note that the stored voltage of the battery 7 is appropriately boosted by the chopper 9 regardless of whether it is the instantaneous drop mode or the power failure mode.

  In this way, since all the energy necessary for operating the load facility is supplied from the capacitor 7 through the second converter 6, the load 3 is not affected by an instantaneous drop or a power failure.

  Note that the AC voltage of the AC power supply 2 is constantly measured regardless of whether it is in a steady state, in a sag mode, or in a power failure mode. Based on the measurement results, switching between modes and switching to steady operation is performed at any time. Is called.

  For this reason, if the storage battery 7 has the same storage capacity, the conventional instantaneous decrease except for the time when all the storage capacity of the storage battery 7 is consumed, unless the voltage drop is continuously greater than the set value or a power failure occurs. If the operation of the load facility can be compensated for longer than the compensation device, that is, if the operation of the load facility is compensated for the same time, the storage capacity can be reduced. Thereby, the capacitor | condenser 7 can be reduced in size and the voltage reduction and the power failure compensation apparatus 1 can be reduced in size and cost.

  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, in the above embodiment, an electric double layer capacitor is used as the capacitor 7, but various types such as an electrolytic capacitor, a lithium ion capacitor, and a battery can be used.

  2 .... AC power supply, 3 .... Load, 4 .... AC switch, 5 .... First converter, 6 .... Second converter, 7 .... Capacitor, 8 .... Control unit

Claims (1)

  A switching unit (4) that is supplied with AC power from the power source (2) and outputs AC power to the load (3) side, and a first conversion unit that converts AC power supplied from the power source (2) into DC power (5), a second converter (6) that converts the DC power output from the first converter (5) into AC power and outputs the AC power to the load (3), and the first converter Power storage unit (7) charged with DC power from the unit (5) or the second conversion unit (6), the switching unit (4), the first conversion unit (5), and the second conversion A control unit (8) for controlling the unit (6), and when the voltage drop of the power source (2) is smaller than a preset value, the control unit (8) causes the switching unit (4) to The DC power output from the first converter (5) and the storage of the power storage unit (7). The power is converted into AC power by the second converter (6) and output to the load (3). When the voltage drop of the power source (2) is larger than the set value or a power failure, the control is performed. The unit (8) shuts off the switching unit (4) and the first conversion unit (5), and the stored power of the power storage unit (7) is converted into AC power by the second conversion unit (6). A voltage sag / blackout compensator characterized by being converted and output to the load (3) side.