JP2015149868A - Voltage sag/power failure compensation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage sag/power failure compensation device that can be made compact and lightweight even when applied to a three-phase 4-wire load.SOLUTION: A voltage sag/power failure compensation device includes a switching unit 4, a conversion unit 5 for converting AC power into DC power, a power storage unit 6, and a control unit 7 for controlling the switching unit 4 and conversion unit 5. The voltage sag/power failure compensation device is configured so that the control unit 7 controls so that the switching unit 4 is cut off and the power stored in the power storage unit 6 is converted, by the conversion unit 5, into AC power and outputted to the load 3 side, when the voltage of AC power supplied from a power supply 2 to the switching unit 4 lowers or the power supply is interrupted. Furthermore, a transformer 8 is provided between the switching unit 4 and conversion unit 5, a primary winding 8a of the transformer 8 is connected with the AC power output side of the conversion unit 5, a secondary winding 8b of the transformer 8 is connected with the load 3, and the common connection on the secondary of the transformer 8 is connected with a ground line connecting the power supply 2 and 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, a voltage sag compensator has been introduced in important load facilities such as production facilities in order to prevent the operation of the facilities from being obstructed when the power supply voltage drops momentarily due to a lightning strike, etc. (For example, refer to Patent Document 1).

  In the steady state, the voltage sag compensator disclosed in Patent Document 1 alternately turns on (turns on) an AC switch (anti-parallel connected thyristor) to supply AC power from a system power source to a load. When a voltage drop or power failure occurs instantaneously in the AC power from the system power supply due to a lightning strike, etc., the AC switch is cut off (OFF), the storage voltage (DC voltage) of the storage unit is boosted with a chopper, and the inverter In this way, the power supply is compensated for power supply at the time of a power failure or power failure by converting the voltage into AC voltage and supplying AC power to the load.

JP 2002-010528 A

  By the way, when applying the voltage sag compensator as disclosed in Patent Document 1 to a three-phase four-wire load, as shown in FIGS. In addition to the power storage unit 16 and the control unit 17, the transformer 18 is provided. The AC switch 14 is provided between the AC power supply 12 and the load 13, and the transformer 18 is provided between the AC switch 14 and the load 13. The primary side (delta connection) of the transformer 18 is connected to the output side of the AC switch 14, the secondary side (star connection) is connected to the load 13, and the secondary side common connection (neutral point) Is generally connected to a ground line connecting the AC power supply 12 and the load 13 to obtain a three-phase four-wire output.

  However, when such a configuration is adopted, since the steady-state power supply current to the load 13 continues to flow in the transformer 18 in addition to the compensation current from the power storage unit 16, as the transformer 18, In addition, a capacity that is equal to or higher than the rated capacity of the load 13 is required for continuous rating. Therefore, the size, mass, and cost of the device 11 are considerably increased as compared with the compensation device for the three-phase three-wire load. Moreover, in order to remove the switching noise contained in the alternating current power output of the conversion part 15, it is necessary to provide the alternating current reactor (ACL) 19 grade | etc., And the dimension, mass, and cost increased further.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a voltage sag / power failure compensation device that can be reduced in size and weight even when applied to a three-phase four-wire load. And

In order to solve the above-described problem, the voltage sag / power failure compensation device 1 of the present invention includes a switching unit 4 that is supplied with AC power from a power source 2 and outputs AC power to the load 3 side, and an AC output from the switching unit 4 A conversion unit 5 that converts electric power into DC power, a power storage unit 6 that is charged by DC power output from the conversion unit 5, and a control unit 7 that controls the switching unit 4 and the conversion unit 5 are provided. When the voltage of the AC power supplied from the power source 2 to the switching unit 4 is reduced or a power failure occurs, the control unit 7 shuts off the switching unit 4 and converts the stored power of the power storage unit 6 to the conversion unit. 5, the AC power is converted to AC power and output to the load 3 side. The voltage sag / blackout compensation device 1 further includes a transformer 8 between the switching unit 4 and the conversion unit 5. Preparation The primary winding 8a of the transformer 8 is connected to the AC power output side of the converter 5, the secondary winding 8b of the transformer 8 is connected to the load 3, and 2 of the transformer 8 A common connection portion on the next side is connected to a ground line connecting the power source 2 and the load 3.

  The voltage sag / blackout compensator of the present invention includes a transformer between the switching unit and the conversion unit, the primary winding of the transformer is connected to the AC power output side of the conversion unit, and the secondary winding of the transformer. Since the wire is connected to the load and the common connection on the secondary side of the transformer is connected to the ground line connecting the power source and the load, the transformer has a steady-state feeding current to the load. Does not flow continuously, and a large current (current equivalent to the steady-state power supply current to the load) flows only during the compensation time to compensate for instantaneous voltage drop or power failure. As a result, the apparatus can be reduced in size and weight. In addition, the current flows even when storing the power storage unit, but it is small compared to the steady-state power supply current to the load, and much smaller and lighter than the one that the steady-state power supply current to the load acts. Can be achieved. In addition, it is possible to omit an ACL (AC reactor) by using the leakage impedance of the transformer, and in this case, the device can be further reduced in size and weight.

1 is a single line diagram illustrating a voltage sag / power failure compensation device according to an embodiment of the present invention. It is a double track diagram similarly showing the connection state around the transformer. It is a single line figure which shows the conventional sag / power failure compensation apparatus. It is a double track diagram which shows the connection state around the transformer of the conventional sag / compensation device.

  Next, an embodiment of the voltage sag / power failure compensation device of 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 (hereinafter referred to as AC power source) 2 and outputs AC power to the load 3 side (reverse parallel). Connected thyristor (hereinafter referred to as AC switch) 4, a conversion unit (inverter and chopper) 5 that converts AC power output from the AC switch 4 into DC power, and DC power output from the conversion unit 5 Power storage unit (electric double layer capacitor) 6 charged by the control unit 7, a control unit 7 for controlling the AC switch 4 and the conversion unit 5, and a transformer 8.

  The AC switch 4, the conversion unit 5, the power storage unit 6, the control unit 7, and the transformer 8 are connected to each other to configure the voltage sag / power failure compensation device 1. Specifically, as shown in FIG. 1, an AC switch 4 is connected between the AC power supply 2 and the load 3, and a conversion unit 5 is connected to a power line branched from between the AC switch 4 and the load 3, Further, a power storage unit 6 is connected to the exchange unit 5. A transformer 8 is connected between the AC switch 4 and the converter 5. The control unit 7 is connected to the AC switch 4 and the conversion unit 5 in order to send a control signal.

  More specifically, the connection of the transformer 8 will be described. The transformer 8 has a primary winding (star connection) 8a connected to the AC power output side of the converter 5 as shown in FIG. (Star connection) 8b is connected to the load 3, and the secondary common connection (neutral point) is connected to the AC power supply 2 and the load 3 and connected to the grounded ground wire to connect the three-phase 4 Line output is obtained. The transformer 8 is provided with a delta connection as the tertiary winding 8c.

  The instantaneous voltage drop / blackout compensation device 1 configured in this way supplies alternating current power from the alternating current power source 2 to the load 3 by alternately conducting the alternating current switches 4 in a steady state. At the same time, AC power from the AC switch 4 is sent to the converter 5 via the transformer 8, and the power storage unit 6 is stored with DC power obtained by operating the converter 5 in a converter.

  When the AC power from the AC power source 2 is reduced in voltage or caused by a lightning strike or the like, the AC switch 4 is shut off and the storage voltage (DC voltage) of the storage unit 6 is changed to the chopper (DC) of the conversion unit 5 under the control of the control unit 7. -DC converter) boosts the voltage, and further converts it into an AC voltage by the inverter of the converter 5 and supplies it to the load 3 via the transformer 8, thereby compensating for power supply at the time of an instantaneous drop or power failure.

  Therefore, in the steady state, only the current necessary for storing the power storage unit 6 flows in the steady state, and the steady-state power supply current to the load 3 does not flow continuously. Since a large current (current equivalent to the steady-state power supply current to the load 3) flows only during the compensation time to compensate for low or power failure, the transformer 8 can be handled with a short-time rating, and as a result, the device 1 is small. And weight reduction can be achieved.

  In addition, since the delta connection is provided as the tertiary winding 8c, it is possible to suppress distortion that occurs when both the primary winding 8a and the secondary winding 8b are star-connected. Furthermore, by using the leakage impedance of the transformer 8, the AC reactor (ACL) can be omitted, and the device can be further reduced in size and weight.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited to the said embodiment, It can be implemented in various changes within the scope of this invention.

  For example, in the above embodiment, an electric double layer capacitor is used as the power storage unit 6, but various other types of capacitors and batteries such as an electrolytic capacitor and a lithium ion capacitor can be used.

  1 ・ ・ Instantaneous voltage drop ・ Power failure compensation device 2 ・ ・ AC power supply (system power supply) 3 ・ ・ Load 4 ・ ・ AC switch (switching unit) 5 ・ ・ Conversion unit 6 ・ ・ Power storage unit 7 ・ ・Control unit, 8 ... Transformer, 8a ... Primary winding, 8b ... Secondary winding

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 converter (5) that converts AC power output from the switching unit (4) into DC power. ), A power storage unit (6) charged by DC power output from the conversion unit (5), and a control unit (7) for controlling the switching unit (4) and the conversion unit (5). When the voltage of the AC power supplied from the power source (2) to the switching unit (4) is reduced or a power failure occurs, the control unit (7) shuts off the switching unit (4) and A voltage sag / blackout compensator configured to convert the stored power of the unit (6) into AC power by the conversion unit (5) and output it to the load (3) side. In addition, the switching unit (4) and the change A transformer (8) is provided between the converter (5) and the primary winding (8a) of the transformer (8) is connected to the AC power output side of the converter (5). The secondary winding (8b) of (8) is connected to the load (3), and the secondary common connection of the transformer (8) is connected to the power source (2) and the load (3). It is connected to the grounding line that connects the two.