JP2008259294A - Instantaneous voltage drop compensator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that technical difficulty increases when circuit voltage becomes high and economical manufacture becomes difficult in a high speed switch used for an instantaneous voltage drop compensator. <P>SOLUTION: A first series transformer is connected between an AC power supply and a load. The high speed switch and a second series transformer are connected in parallel to a primary side of the series transformer. An output side of an inverter is connected to a primary side of the second series transformer. When instantaneous voltage drops, voltage generated from the inverter is superimposed on power voltage through the second series transformer and the first series transformer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an instantaneous voltage drop compensation device.

  As an instantaneous voltage drop compensation device, a device as disclosed in Patent Document 1 is known. The series type compensation device disclosed in Patent Document 1 is configured as shown in FIG. In the figure, 1 is a three-phase AC power source, 2 is a load, and a high-speed switch 3 is connected between the load 2 and the AC power source 1. 4 is a series transformer, the secondary winding of which is connected in parallel with the high-speed switch 3, and the primary winding is connected to the output side of the inverter 5. Reference numeral 6 denotes an energy storage element, and reference numeral 7 denotes a charger for charging the energy storage element 6.

In the instantaneous voltage drop compensator configured as shown in FIG. 4, when the power supply is normal, the power supply to the load 2 is supplied via the high-speed switch 3 as indicated by the solid line arrow, and when the instantaneous voltage drop occurs on the power supply side The load voltage is kept constant by turning off the high-speed switch 3 and generating a voltage commensurate with the amount of voltage drop on the power supply side from the energy storage element 6 via the inverter 5 as indicated by the dotted line arrow.
JP 2006-197792 A

  The high-speed switch 3 used in the instantaneous voltage drop compensation device is adapted to the circuit voltage by connecting a plurality of semiconductor elements connected in series corresponding to the voltage in antiparallel. Therefore, the higher the circuit voltage, the greater the number of semiconductor elements connected in series, making it technically difficult to share the voltage when the switch is cut off. The number of elements is increased in order to provide a margin for voltage sharing. In addition, it is necessary to improve the insulation performance by increasing the circuit voltage, and technical difficulties such as insulation of cooling fins for cooling semiconductor elements, insulation of drive circuits of semiconductor elements, insulation of circuit charging parts increase. However, economical production is difficult.

That is, when an IGBT, GTO, and thyristor are used as semiconductor elements to configure a high-speed switch, the applied circuit voltage that is technically easy to manufacture is a low-voltage or high-voltage circuit. When applied to a circuit exceeding 7000 V, the number of elements in series increases, which is technically difficult to realize and cannot be economically manufactured.
Conversely, if the configuration of the instantaneous voltage drop compensator of FIG. 4 is applied to a large current system at a low voltage, the number of semiconductor elements to be used increases and the current sharing of the elements becomes technically difficult. Can't produce economical equipment.

  In consideration of the system voltage of the power source, as shown in FIG. 5, a step-down transformer 8 is connected between the power source 1 and the instantaneous voltage drop compensator, and between the instantaneous voltage drop compensator and the load 2. It has also been proposed to connect the step-up transformer 9 to. In this compensation device, the power supply voltage is once stepped down by the step-down transformer 8, and then passed through the step-up transformer 9 to supply high power to the load 2. In the case of this device, two transformers equivalent to the system capacity are required, and no load loss occurs, making it impossible to manufacture an economical device.

  Accordingly, an object of the present invention is to provide an instantaneous voltage drop compensator capable of appropriately selecting a circuit voltage of a high-speed switch.

The present invention provides an instantaneous voltage drop compensator that superimposes energy stored in an energy storage element on a system voltage via an inverter when an instantaneous voltage drop of an AC power supply is performed.
A first series transformer is connected between the AC power source and the load, a high-speed switch and a second series transformer are connected in parallel to the primary side of the series transformer, and the primary side of the second series transformer is connected. The output side of the inverter is connected.

  Further, according to the present invention, the inverter according to claim 1 is a single-phase inverter, and the single-phase inverter of each phase includes the first series transformer, the high-speed switch, and the second series transformer, respectively. A compensator is configured, and this single-phase inverter compensator is installed in each phase between the AC power supply and the load.

  Further, the present invention is characterized in that the first series transformer has three windings, and a high-speed switch is connected between each phase of the three-winding DC transformer.

  As described above, according to the present invention, the high-speed switch circuit voltage of the high-speed switch is connected to the primary side of the series transformer because the high-speed switch that is on when the power supply voltage is normal and the second series transformer are connected. Can be selected to an appropriate value, and can be installed in a high-voltage system where it is difficult to directly install a high-speed switch.

  FIG. 1 is a configuration diagram of a single connection display showing a first embodiment of the present invention, wherein 10 is a three-phase AC power source, 11 is a load, and a first series between the load 11 and the AC power source 10 is shown. The secondary winding 12s of the transformer 12 is connected. The primary winding 12p of the series transformer 12 is Δ-connected, and high-speed switches 13 (13R, 13S, 13T) are connected between the respective phases. The high-speed switch 13 has a configuration in which elements such as GTO are connected in antiparallel, and is controlled to be turned on / off via a control circuit (not shown). The primary winding 12p of the first series transformer 12 is connected to the secondary winding 14s of the second series transformer 14, and the primary winding 14p of the series transformer 14 is connected to the three-phase inverter 15. The output side is connected. Reference numeral 16 denotes an energy storage element, and reference numeral 17 denotes a charger for charging the energy storage element 16.

The circuit of FIG. 1 operates as follows.
When the three-phase AC power supply 10 is normal, power is supplied from the power supply 1 to the load 11 via the series transformer 12 as indicated by an arrow A. At this time, the high-speed switches 13R to 13T connected to the primary winding 12p of the series transformer 12 are in a short-circuit state, and current flows between the phases as indicated by a solid arrow B. In addition, the energy storage element 16 is charged in advance via the battery 17.

In the above state, when an instantaneous voltage drop occurs in the power supply 1 for some reason, the control circuit immediately detects this and turns off the high-speed switch 13 and generates a voltage corresponding to the instantaneous voltage drop to the inverter 15. Control as much as possible. As a result, the inverter 15 generates a voltage corresponding to the voltage drop, superimposes the generated voltage on the system voltage via the series transformer 12 along the route indicated by the dotted arrow C, and makes the load voltage constant.
The circuit at this time includes a current from the power source 1 to the load 12 when a voltage drop occurs as indicated by an arrow D indicated by a one-dot chain line, a primary winding 12p of the series transformer 12, and a secondary of the series transformer 14. A current indicated by an arrow D flowing between the windings 14s flows.
When the voltage drop phenomenon is canceled, the high speed switch 13 is turned on again, and the voltage generation from the inverter 15 is stopped.

  According to this embodiment, it is possible to select an appropriate value for the circuit voltage of the high-speed switch, and it is possible to economically manufacture a circuit exceeding 7000V. Although a series transformer 12 is added, no voltage is generated in the series transformer when the voltage is normal, so no-load loss can be ignored.

FIG. 2 shows a second embodiment, and the circuit of FIG. 1 shows a case where a three-phase inverter is used. In the embodiment shown in FIG. The element and the charger are separately configured for each single-phase inverter, display only the R phase, and the other S phase and T phase are configured in the same manner. That is, the single-phase inverter of each phase is connected to the first series transformer, the high-speed switch, and the second series transformer to form a single-phase inverter compensator, and this single-phase inverter compensator is used as an AC power source. An instantaneous voltage drop compensator is configured for each phase between the loads.
In addition, when providing a single phase inverter compensation apparatus in each phase, as a matter of course, the energy storage element and the charger may have a common configuration for each phase, and they are appropriately selected.
Since the operation and effect of this embodiment are the same as those in FIG.

  FIG. 3 shows a third embodiment. In this embodiment, the first series transformer 12 ′ is a three-winding transformer, and high-speed switches 13R to 13T are connected between the respective phases. Is the same as that of the embodiment of FIG. 1, and the operation and effect are the same as those of FIG.

The block diagram which shows embodiment of this invention. The block diagram which shows other embodiment of this invention. The block diagram which shows other embodiment of this invention. The block diagram of the conventional instantaneous voltage drop compensation apparatus. The block diagram of the other conventional instantaneous voltage drop compensation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... AC power supply 11 ... Load 12 ... 1st series transformer 13 ... High speed switch 14 ... 2nd series transformer 15 ... Inverter 16 ... Energy storage element 17 ... Charger

Claims (3)

In the instantaneous voltage drop compensation device that superimposes the energy stored in the energy storage element on the system voltage via the inverter when the instantaneous voltage drop of the AC power supply,
A first series transformer is connected between the AC power source and the load, a high-speed switch and a second series transformer are connected in parallel to the primary side of the series transformer, and the primary side of the second series transformer is connected. An instantaneous voltage drop compensator characterized by connecting the output side of the inverter. The inverter is a single-phase inverter, and a single-phase inverter compensator including the first series transformer, the high-speed switch, and the second series transformer is configured for each phase of the single-phase inverter. 2. The instantaneous voltage drop compensator according to claim 1, wherein an inverter compensator is installed in each phase between the AC power supply and the load. 2. The instantaneous voltage drop compensator according to claim 1, wherein the first series transformer has three windings, and a high-speed switch is connected between each phase of the three-winding DC transformer.

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