JP2000069763A - Power supply device for electric railway - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for electric railway, capable of completely removing three-phase disequilibrium on power supply side. SOLUTION: This power supply device for electric railway consists of an AC/DC converter 4 which converts AC output on the load side of a three-phase transformer 3 connected to AC high voltage power supply for an electric railway into direct current, an orthogonal converter 5 which converts DC output of the AC/DC converter 4 into alternating current, and a single-phase transformer 6 which supplies single-phase AC power to an electric railway load 2 by transforming AC output of the DC/AC inverter 5. A power storage device 7 is connected with the junction of the AC/DC converter 4 and the DC/AC inverter 5, and the power storage device 7 is charged from the power supply or load side at the time of no load or light load, thus it is possible to conduct discharging to the load side for compensation of supply power at the time of presence of load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a railway power supply device for supplying power to a railway load in a railway AC feeding circuit.

[0002]

2. Description of the Related Art In an AC feeding circuit for railways, an AC power supply has three phases and a train line has a single phase.
The three-phase AC high-voltage power supply is converted to a single-phase through a Scott transformer (1) to supply a single-phase AC to the railway load (2).
At this time, the T seat and M of the single-phase secondary side of the Scott transformer (1)
If the same railway load is simultaneously applied to the three positions, the three-phase voltages on the primary side are balanced, but in practice, the same railway load is rarely simultaneously applied to the T and M positions. The primary-side phase voltages are unbalanced across the primary side. for that reason,
A reactive power compensator is installed on the three-phase primary side to eliminate three-phase imbalance and voltage fluctuation.

[0003]

SUMMARY OF THE INVENTION Scott Transformer (1)
Even if an attempt is made to eliminate the three-phase imbalance by installing a reactive power compensator on the three-phase primary side, it is difficult to completely eliminate the imbalance due to time delays, errors, etc. When regenerative power is generated from the load to the grid side, there is a problem that three-phase imbalance is promoted. In addition, while large power is consumed only for a short time when a train passes, equipment capacity corresponding to the large power is required only for the short time,
In addition, a time imbalance in power consumption occurs. There is also a disadvantage that the harmonic current generated by the load (2) flows out to the power supply system side.

It is an object of the present invention to provide a railway power supply device capable of completely eliminating three-phase imbalance on the power supply side.

[0005]

SUMMARY OF THE INVENTION The present invention provides an AC / DC converter for converting a load-side AC output of a three-phase transformer connected to an AC high-voltage power supply for railways to DC, and an AC / DC converter for converting the DC output of the AC / DC converter to AC. And a single-phase transformer for transforming the AC output of the quadrature converter to supply single-phase AC power to the railway load, and the AC-DC converter and the quadrature converter A power storage device is connected to the connection point, and the power storage device is charged from the power supply side or the load side when there is no load or light load, and is discharged to the load side when there is a load to supplement the supplied power.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply device for electric railway according to the present invention will be described below with reference to FIG. In the figure, (2) is a railway load, (3) is a three-phase transformer, (4) is an AC / DC converter (converter), (5) is a quadrature converter (inverter), (6) is a single-phase transformer, ( 7) is a power storage device.

[0007] The three-phase transformer (3) is connected to a three-phase AC high-voltage power supply (not shown) for electric railways. The converter (4) is connected to the secondary (load) output of the three-phase transformer (3) and converts the AC output of the transformer to DC. The inverter (5) is connected to the output of the converter (4) and reconverts the converter DC output to AC. The single-phase transformer (6) is connected to the output of the inverter (5) and transforms the inverter AC output to supply single-phase AC power to the railway load (2). The power storage device (7) is a capacitor or a rechargeable battery connected to a connection point between the converter (4) and the inverter (5).

Next, the operation of the present invention based on the above configuration will be described. First, an AC high-voltage power supply is transformed (step-down) by a three-phase transformer (3), and its output is converted to DC by a converter (4), and then the DC output is converted again to AC of a predetermined frequency by an inverter (5). . The AC output of the inverter (5) is transformed by the single-phase transformer (6) to supply single-phase AC power to the railway load (2).

[0009] Then, the three-phase AC voltage on the power supply side is once converted to DC, then converted back to AC, and supplied with single-phase AC power to the railway load (2) via the single-phase transformer (6). Therefore, the direct current is interposed between the three-phase transformer (3) and the single-phase transformer (6), so that the influence on the single-phase side is equally added to the three-phase side, and each phase on the three-phase side is added. Voltage imbalance is eliminated.

The converter (4) is operated at no load or light load during which the train does not pass to charge the power storage device (7) from the power supply side or the load side. 5) is operated to discharge the power storage device (7) to the load side to supply power to the load (2).

Then, if the power supplied to the converter (4) is (Ps), the power supplied by discharging the power storage device (7) is (Pc), and the total power supplied to the load (2) is (PL), From PL = Ps + Pc, Ps = PL -Pc
Holds. Accordingly, when the power (Pc) is supplied to the load (2) every time the power storage device (7) is discharged, the power (Ps) supplied from the power source can be reduced by that much, and the peak power of the power source can be suppressed, and the power consumption can be reduced. Equilibrium of power imbalance over time can provide a sufficient capacity.

A three-phase transformer (3) and a single-phase transformer (6)
The three-phase side and the single-phase side are separated by direct current due to the direct current between them, so that the harmonic current generated from the railway load (2) is blocked by direct current and can be prevented from flowing out to the power supply system side. .

[0013]

According to the present invention, in a device for supplying electric power from a three-phase AC power supply to an electric railway load, the AC output from the AC power supply via the three-phase transformer is temporarily converted into DC by a converter, Since the inverter was reconverted to AC and single-phase AC power was supplied to the load via the single-phase transformer, direct current was interposed between the three-phase transformer and the single-phase transformer, and the influence on the single-phase side was reduced. It is added evenly to the phase side, and the imbalance of each phase voltage on the three phase side is eliminated.

Further, since the power storage device is charged at no load or light load and discharged at the time of load to supply power to the load, the power supplied from the power source is reduced by the power supplied by the discharge of the power storage device. To reduce electricity bills,
There is room for equipment capacity. Further, since the power supply side and the load side are separated by direct current, it is possible to prevent the harmonic current generated from the load from flowing out to the power supply system side.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a railway power supply device according to the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional railway power supply device.

[Explanation of symbols]

 2 Load 3 Three-phase transformer 4 AC / DC converter (converter) 5 Quadrature converter (inverter) 6 Single-phase transformer 7 Power storage device

Claims (2)

[Claims] 1. An AC / DC converter for converting a load-side AC output of a three-phase transformer connected to a railway AC high-voltage power supply into DC.
A quadrature converter for converting a DC output of the AC / DC converter into an AC, and a single-phase transformer for transforming the AC output of the quadrature converter to supply a single-phase AC power to a railway load. Power supply for railways. 2. A power storage device is connected to a connection point between the AC / DC converter and the orthogonal converter, and the power storage device is charged from the power supply side or the load side when there is no load or light load, and discharged to the load side when there is a load. The electric power supply device for railways according to claim 1, wherein the supplied electric power is supplemented.