JPH08207626A - Reactive power compensator - Google Patents

Abstract

PURPOSE: To lower direct current magnetic deflection in a transformer so as to prevent a stop of a device due to output overcurrent from an inverter by connecting the transformer on the output side of the inverter using a self arc- extinguishing type semiconductor element and connecting a series capacitor and a series reactor in series on the output side of the transformer. CONSTITUTION: A transformer 27 is connected to the output side of an inverter 28 using a self arc-extinguishing type semiconductor element, while a series capacitor 31 is arranged on the output side of the transformer 27, and direct current distribution voltage generated in the feeder side is cut off. In this process, as an inductance between the inverter 28, which reduces higher harmonics flowing out to a feeder system from a self-excited type reactive power compensator, and the feeder system is canceled by means of the series capacitor 31, a series reactor 32 is additionally connected in series with the series capacitor 31. In this way, a stop of a device because of output overcurrent of the inverter 28 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for compensating reactive power generated by a vehicle in a rail AC feeding circuit, and is a self-excited type reactive device using a self-extinguishing type semiconductor device such as a gate turn-off thyristor. The present invention relates to a power compensator.

[0002]

2. Description of the Related Art Presently, as shown in FIG. 2, a reactive power compensator for an AC feeding circuit has (1) a self-excited reactive power compensator 1 provided on the side of a three-phase power system, and (2). Two types of systems are adopted: a separately excited type reactive power compensator 2 provided at a feeder bus of a substation or a feeder section SP. In FIG. 2, 3 is a Scott connection transformer, and 4 is a feeder.

[0003]

As shown in FIG. 3, the separately-excited reactive power compensator has a parallel capacitor 11 fixed to reduce the harmonics generated by the high impedance transformer 12, the thyristor switch 13, and the thyristor switch 13. However, a self-excited reactive power compensator is more advantageous in terms of size and performance due to recent element development and improvement of power conversion technology. .

Therefore, the self-excited reactive power compensator 21 as shown in FIG. 4 is used for stabilizing the voltage of the substation feeding bus and the feeding section SP where the separately excited reactive power compensator has been used until now. Is considered to apply. However, as shown in FIG. 4, in the case where the electric bus 22 of the substation includes a series capacitor 23 for compensating for the voltage drop due to the inductance of the Scott connection transformer 3 of the substation and the inductance on the power source side, the following is performed. Problems arise.

That is, the electric car 24 is a section 25.
(When the M seat and the T seat of the Scott connection transformer 3 cannot be electrically connected, the trolley wire 26 is provided with an insulation section), the transformer installed on the electric car 24 side when passing through Inrush current flows through the vessel. Since this inrush current is a vertically asymmetrical wave, a DC voltage is added to the series capacitor 23, and the feeding bus voltage or feeding voltage becomes a voltage on which a DC component is superimposed. The voltage of this DC component may be 10% or more of the AC voltage, and when the self-excited reactive power compensator 21 is used as shown in FIG. 4, the transformer 27 of the device 21 affects the influence of this DC component. As a result, DC bias is generated, the output of the inverter 28 becomes excessive, and the device stops. In FIG. 4, 29 is a rail.

The present invention has been made in view of the above points, and an object thereof is to reduce the DC bias magnetism of a transformer included in a self-excited reactive power compensator and prevent the device from being stopped due to an output overcurrent of an inverter. It is to provide a reactive power compensator.

[0007]

SUMMARY OF THE INVENTION The present invention uses a self-extinguishing type semiconductor device in a reactive power compensator connected to a feeding circuit of an AC electric railway to perform reactive power compensation and voltage stabilization. The inverter, the transformer connected to the output side of the inverter, and the series capacitor and the series reactor connected in series to the output side of the transformer.

[0008]

The reactive power compensator of the present invention is used, for example, provided on the feeder side of an AC feeder circuit. For substation and electric bus
In a device that includes a series capacitor for compensating for the voltage drop due to the inductance of the Scott connection transformer at the substation and the inductance on the power source side, if a DC component is superimposed on the feeder voltage, the DC component is compensated for reactive power. It is cut by the series capacitor of the device. Therefore, it is possible to avoid a situation in which the transformer of the reactive power compensator causes DC bias magnetism, the inverter output becomes excessive, and the device stops.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the present invention, a series capacitor 31 is provided on the output side of the transformer 27 of the self-excited reactive power compensator 21 provided on the feeder as shown in FIG. It was configured to cut off the voltage. In this case, the series capacitor 31 offsets the inductance between the inverter and the feeder system (which conventionally used the leakage inductance of the transformer of the device) that reduces the harmonics flowing out of the self-excited var compensator into the feeder system. Therefore, the series reactor 32 is further connected.

By installing this series capacitor 31,
When the DC voltage is superimposed on the feeder circuit as shown in FIG. 4, it is possible to reduce the DC bias magnetization of the transformer 27 in the self-excited reactive power compensator as compared with the case where the series capacitor 31 is not installed. .

[0011]

As described above, according to the present invention, in the self-excited reactive power compensator installed on the feeder bus and feeder of the AC electric railway to suppress the voltage fluctuation, the self-excited reactive power compensator is provided on the output side of the device. Since the series capacitor is installed, it is possible to reduce the DC bias magnetism of the transformer included in the self-excited reactive power compensator and prevent the inverter from being stopped due to output overcurrent.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a feeder circuit of an AC electric railway.

FIG. 3 is a circuit diagram showing an example of a separately-excited reactive power compensator.

FIG. 4 is a circuit diagram showing an installation example of a self-excited reactive power compensator in a feeder circuit of an AC electric railway.

[Explanation of symbols]

 1, 21 ... Self-excited reactive power compensator 2 ... Separately excited reactive power compensator 3 ... Scott connection transformer 4 ... Feeding wire 22 ... Feeding bus 23, 31 ... Series capacitor 24 ... Electric car 25 ... Section 26 ... Trolley wire 27 ... Transformer 28 ... Inverter 29 ... Rail 32 ... Series reactor

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02M 7/515 G 9181-5H

Claims (1)

[Claims] 1. Connected to a feeder circuit of an AC electric railway,
In a reactive power compensator for compensating reactive power and stabilizing voltage, an inverter using a self-arc-extinguishing semiconductor element, a transformer connected to the output side of the inverter, and a series connected to the output side of the transformer. A var compensator, comprising: a series capacitor and a series reactor connected to each other.