JPH05338480A - Power feeding method for ac electric railway - Google Patents

Abstract

PURPOSE:To restrain unbalanced voltage fluctuation of an upstream three-phase power supply due to the unbalance of the secondary side load of a transformer simply and at a low price in a power feeding method for an AC electric railway using a Scott connection transformer. CONSTITUTION:Voltages of single-phase power supplies of M-seat and T-seat of a Scott connection transformer 2 are monitored, and when a voltage unbalance occurs, an undercompensation power supply formed from a high voltage side power supply is connected in a series between the low voltage side power supply out of single-phase power supplies of both seats and a train load 3m or 3t so as to restrain unbalanced voltage fluctuation of a three-phase power supply 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power feeding method for an AC railway which converts a three-phase power source into a single-phase power source by a Scott connection transformer and feeds the train load of the railway.

[0002]

2. Description of the Related Art Conventionally, in an AC railway such as the Tokaido Shinkansen, since the train load is a single-phase load, a three-phase power source is converted into a single-phase power source by a Scott connection transformer, and the secondary side of this transformer is converted. The M- and T-seat single-phase power supplies go up, and power is supplied to train loads such as down trains (hereinafter, M-seat and T-seat train loads).

The Scott connection transformer has the advantage that when the train loads on both seats are equal, it becomes a three-phase balanced load for the three-phase power source on the primary side of the transformer and does not adversely affect the power source voltage.

[0004]

In the case of the conventional power feeding method using the Scott connection transformer, the power feeding equipment is used to prevent the unbalanced voltage fluctuation of the three-phase power source due to the unbalanced train load on both seats. There is a problem that a separate large-scale and expensive compensator is required.

That is, each train on both seats is a fluctuating load that requires the maximum electric power at the time of acceleration from stop to travel, and in normal operating conditions, the number of trains on both seats is not equal and the condition of each train is also Individually different.

Therefore, in this type of AC electric railway, a situation in which the train loads on both seats of the Scott connection transformer are not equal to each other easily occurs, and the unbalance of the loads causes an unbalanced voltage fluctuation of the three-phase power supply. It should be noted that changes in the train load of the M seat cause the U and W phase currents of the three-phase power supply to increase and decrease, and changes in the train load of the T seat cause the V phase current of the three-phase power supply to increase and decrease.
The voltage of the phase power supply becomes unbalanced.

In order to prevent this voltage imbalance,
Conventionally, it is necessary to provide a compensating device such as a large-scale and expensive capacitor facility that suppresses load fluctuation of both seats on the secondary side of the Scott connection transformer separately from the power feeding facility. It is an object of the present invention to prevent unbalanced voltage fluctuations of a three-phase power supply due to unbalanced train loads on both seats by a power supply facility without providing a conventional compensator.

[0008]

In order to achieve the above-mentioned object, in the AC electric power feeding method of the present invention, the voltage of the single-phase power source of the M-seat and the T-seat of the Scott connection transformer is monitored and the voltage unbalanced. When equilibrium occurs, the shortage compensating power supply formed from the power supply on the high voltage side is injected in series between the power supply on the low voltage side and the train load of the single-phase power supply on both sides, and the voltage of the single-phase power supply on both sides is injected. Prevents unbalance and suppresses unbalanced voltage fluctuations in the three-phase power supply.

[0009]

In the case of the AC electric power feeding method of the present invention having the above-described structure, the M seat, T on the secondary side of the Scott connection transformer is used.
When the train load in the seat becomes unbalanced and voltage imbalance occurs, based on the monitoring and detection of this voltage imbalance, the high voltage side, that is, the high voltage side, A shortage compensating power supply formed from a single-phase power supply on the light load side is injected in series. This compensating power supply compensates for the insufficient power supply of the single-phase power supply on the heavy load side, and prevents voltage imbalance between the two seats.

When the voltage imbalance between the two seats is prevented, the imbalance of the three-phase voltage on the primary side of the Scott connection transformer due to the imbalance of the train load is prevented, and the imbalance of the upstream three-phase power supply is prevented. Balanced voltage fluctuations are suppressed. Therefore, a Scott connection transformer can be easily and inexpensively provided by a power feeding method that exchanges the energy of the single-phase power source of both seats according to the excess and deficiency without providing a large-scale and expensive condenser equipment such as the conventional one. The unbalanced voltage fluctuation of the upstream three-phase power supply due to the unbalanced train load on the secondary side of the equipment is suppressed.

[0011]

EXAMPLE One example will be described with reference to FIGS. In FIG. 1, 1 is an upstream three-phase power supply (system power supply), 2 is a Scott connection transformer, and a primary winding 2i is connected to each phase of U, V, W of the three-phase power supply 1 M on the side
A single-phase power source with a voltage phase difference of 90 ° is generated in the two windings 2m and 2t of the Z and T seats.

3m and 3t are train loads of M seat and T seat, 4
m and 4t are normally closed bypass switches for opening and closing the power supply line provided between the two windings 2m and 2t and the overhead lines 5m and 5t of both seats, and 6m and 6t are output voltages of the two windings 2m and 2t ( Transformer secondary side voltage) Transformer for detecting V1, V2, 7m, 7t
Is the train load voltage V3 on the load side of the switches 4m and 4t.
It is a transformer that detects V4.

Reference numerals 8m and 8t denote inverters, and the winding 2
m, 2t single-phase power source is charging transformers 9m, 9t and rectifying / smoothing diodes 10m, 10t, capacitor 1
It is supplied via 1m and 11t. 12m and 12t are injection transformers for injecting the outputs of the inverters 8m and 8t in series to the overhead lines 5m and 5t, and the secondary side is a switch 4m and 4t.
Are installed in parallel.

Reference numeral 13 is a control device for controlling the opening / closing of the switches 4m, 4t and the operation of the inverters 8m, 8t, and is supplied with signals of the detection voltages of the transformers 6m, 6t and 7m, 7t. Further, the control device 13 is configured as shown in FIG. 2, and in the figure, 14m, 14t and 15m, 15t.
Is a smoothing circuit, 16 and 17 are subtractors, 18 is an opening / closing and start / stop command circuit, 19m and 19t are opening / closing control circuits of switches 4m and 4t, 20 is a drive amount calculation circuit, and 21m and 21t are inverters 8m and 8t. It is a drive circuit.

When the train loads 3m and 3t are equally balanced, V1 = V2, the command circuit 18 of the control device 13 outputs a stop command for the inverters 8m and 8t, and this command is used to open / close the control circuit. 19m and 19t are supplied as a close command, and the switches 4m and 4t are both closed and held. At this time, as in the conventional case, the M seat and T of the windings 2m and 2t are
The single-phase power source of the seat is fed to the respective train loads 3m and 3t via the overhead lines 5m and 5t.

Further, in the controller 13, the transformer 6
The detection signals of the output voltages V1 and V2 of m and 6t are smoothed by the smoothing circuit 1.
The signals are averaged by 4m and 14t and supplied to the subtractor 16, which calculates V1-V2. The V1-V2 output signal of the subtractor 16 is supplied to the command circuit 18, and the circuit 18 monitors the voltages of the M-phase and T-phase single-phase power supplies from the output signal of the subtracter 16.

Further, the detection signals of the train load voltages V3 and V4 of the transformers 7m and 7t are averaged by the smoothing circuits 15m and 15t and supplied to the subtractor 17, and the subtractor 17 calculates V3-V4. .. V3-of this subtracter 17
The output signal of V4 is supplied to the driving arithmetic circuit 20, and the arithmetic circuit 20 causes the inverter 8m or 8
The driving amount (output power amount) of t is obtained.

Then, for example, a train load of 3 m is a train load 3
When an unbalance occurs in which the load becomes heavier than t, the voltage fluctuation of V1 <V2 occurs, and the polarity of the output signal of the subtractor 16 becomes negative, the command circuit 18 outputs a start command to the inverter 8t on the light load side. At the same time that the inverter 8t is activated, this command is supplied to the switching control circuit 19m as an open command,
The switch 4m is opened to open the space between the winding 2m and the overhead wire 5m.

Further, based on the output signal of the subtractor 17, the arithmetic circuit 20 obtains the shortage amount of the single-phase power source of the M-slot as the driving amount of the inverter 8t, and the driving circuit 21t controls this driving amount.
And the drive circuit 21t drives the inverter 8t based on this notification.

The single-phase power source for the winding 2t is the transformer 4t.
Also, the diode 10t and the capacitor 11t convert it into a direct current power source and supply it to the inverter 8t. The inverter 8t forms the insufficient amount of alternating current as a shortage compensating power source, and this power source is supplied to both ends of the switch 4m via the injection transformer 12t. Injected in between.

By this injection, the single-phase power source of the winding 2m and the shortage compensating power source are combined in series and fed to the train load 3m,
The shortage of the single-phase power supply for the winding 2m with respect to the train load 3m is compensated by the shortage compensating power supply, and the train load voltage V3 rises and the output voltage V1 rises. By the calculation of the arithmetic circuit 20,
The shortage compensation power source is variably formed so that V3 = V4.

When the train load 3 m returns to a light load and the shortage compensating power source becomes zero, the command circuit 18 outputs a stop command and the inverter 8 based on the notification from the arithmetic circuit 20.
The output of t is stopped and the switch 4m is closed.
At this time, the single-phase power source of the windings 2m and 2t is connected to the train load 3m,
While returning to the original state in which power is supplied to each 3t, V
1 = V2 and V3 = V4.

Next, when an unbalance occurs in which the train load 3t becomes a heavier load than the train load 3m, a voltage fluctuation of V1> V2 occurs, and the polarity of the output signal of the subtractor 16 becomes positive,
The inverter 8m on the light load side is activated and the switch 4t on the heavy load side is opened, and the single-phase power supply of the winding 2t and the shortage compensating power supply formed by the inverter 8m are combined in series to supply power to the train load 3t. The shortage of the single-phase power supply of the winding 2t with respect to the train load 3t is compensated by the shortage compensation power supply. Also in this case, the shortage compensating power supply is variably formed so that V3 = V4, and when the shortage compensating power supply becomes zero, the output of the inverter 8m is stopped and the switch 4t is opened to return to the original state.

Therefore, when the train loads 3m and 3t are unbalanced, the energy of the single-phase power source of the winding 2m or 2t on the light load side is exchanged to the heavy load side via the inverter 8m or 8t and equivalently. Both train loads 3m and 3t are equalized, voltage imbalance between both seats is blocked, and imbalance of three-phase voltage of the primary winding 2i of the transformer 2 is prevented. The unbalanced voltage fluctuation of the three-phase power supply 1 due to the unbalanced train loads 3m and 3t on both seats is suppressed without providing unbalanced compensation equipment such as the above on the secondary side of the transformer 2.

At this time, the inverter 8m or 8t forms a shortage compensating power source corresponding to the shortage of the single-phase power source of the winding 2m or 2t, and this power source is injected in series, so that the inverter 8m, 8t or the like is relatively small. It suffices to have a capacity, and it is formed small and inexpensive. The circuit configuration and the like are not limited to those in the embodiment, and for example, an inverter may not be used for exchanging the single-phase power supply for the windings 2m and 2t.

[0026]

Since the present invention is configured as described above, it has the following effects. Train load 3m, 3t for M seat and T seat on the secondary side of Scott connection transformer 2
Becomes unbalanced and voltage imbalance occurs, based on the monitoring and detection of this voltage imbalance, the high voltage side, that is, the light load, between the single-phase power supply on the low voltage side, that is, the heavy load side, and the train load 3m or 3t. A shortage compensating power supply formed from the load-side single-phase power supply is injected in series, and this compensating power supply compensates for the power supply shortage of the heavy-load single-phase power supply and prevents voltage imbalance between the two seats. The unbalance of the three-phase voltage on the primary side of the transformer 2 due to the unbalance of the loads 3m and 3t is prevented, and the unbalanced voltage fluctuation of the upstream three-phase power supply 1 is suppressed.

Therefore, the power supply method for exchanging the energy of the single-phase power supply of both seats according to the excess or deficiency of the power supply can be easily and inexpensively provided without providing a compensating device such as a large-scale and expensive capacitor equipment as in the prior art. It is possible to suppress unbalanced voltage fluctuations in the upstream three-phase power supply 1 due to unbalanced train loads 3m and 3t on the secondary side of the transformer 2.

[Brief description of drawings]

FIG. 1 is a block connection diagram of one embodiment of a power feeding method for an AC railway according to the present invention.

2 is a detailed block connection diagram of a part of FIG. 1. FIG.

[Explanation of symbols]

 1 3 phase power supply 2 Scott connection transformer 2m, 2t M seat, T seat winding 3m, 3t Train load

Claims (1)

[Claims] 1. A three-phase power supply is connected by a Scott connection transformer to an M
In the AC electric railway power feeding method of converting the single-phase power sources of the Z-seat and the T-seat, and feeding the single-phase power sources of the two-seats to the train loads of the two-seats, the voltage of the single-phase power source of the two-seats is monitored to obtain a voltage. When an imbalance occurs, a shortage compensating power supply formed from a power supply on the high voltage side is injected in series between the power supply on the low voltage side and the train load of the single-phase power supplies on the two seats, and the single-phase power supply on both the seats An AC power feeding method, characterized in that the voltage imbalance of the power supply is prevented to suppress the unbalanced voltage fluctuation of the three-phase power supply.