JPS62238133A - Power supply method for electric railroad - Google Patents

Abstract

PURPOSE:To make it unnecessary to control the phase, prevent the drop of power factor and a higher harmonics, and realize a low cost, by supplying the power, through a power rectifier without output voltage control function when the operation is less than a specific load rate, and through a power rectifier not to be controlled the phase when the operation is at the specific load or more. CONSTITUTION:In the operational area between the no load and a specific load rate, the AC power of a commercial frequency power source is supplied to an electric rolling stock through A/D converting by the first power rectifier, a diode rectifier 11, for example, which has no output voltage control function. On the other hand, in the operational area at a specific load rate or above, as well as the AC power of a commercial frequency power source is A/D converted, the second power rectifier, a thyristor rectifier 14, for example, which cannot control the phase, is operated, whose output power and the output power of the first rectifier 11 are added to feed to the electric rolling stock. In such a composition,the phase control of the power rectifiers is unnecessary, and a low cost is realized as well as the drop of power factor and a higher harmonics are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a power supply method for a DC electric railway that compensates for the voltage drop in a DC overhead contact line.

B1 Summary of the Invention The present invention provides a power supply method for a DC electric railway that converts AC power derived from a commercial frequency power supply into DC and supplies it to electric cars existing under a DC overhead contact line, in which operation from no load to a predetermined load factor is performed. Within the range, power is supplied by the first forward power converter without an output voltage control function, and in the operating range above a predetermined load factor, the second forward power converter, which is not phase-controlled, is operated to adjust the output of the converter. By supplying the electric power and the output power of the first type horn converter to the overhead contact line, phase control during forward power conversion operation is not required, and a decrease in the power factor and generation of harmonics are prevented. This makes it possible to obtain a voltage waveform with less distortion, and also to reliably compensate for the voltage drop in the overhead contact line.

C1 Conventional technology In general, a DC substation equipped with a forward power converter without an output voltage control function is used as a power converter for DC electric railways.
In order to control the output voltage of the substation, a forward power converter having an output voltage control function is provided, as shown in FIG. 3, for example. In FIG. 3, l is a forward power converter which converts AC power led from a commercial frequency power source (not shown) through a diode rectifier transformer 2 to DC, and is composed of, for example, a diode rectifier. The positive output terminal of this diode rectifier 1 is connected to the DC 1?J line 3 to which an overhead contact line (not shown) is connected.The negative output terminal of the diode rectifier 1 is connected to a forward power converter having an output voltage control function. , for example, is connected to the positive side output terminal of a thyristor rectifier 4.The AC input side of this thyristor rectifier 4 is connected to the primary side of a diode rectifier transformer 2 via a thyristor rectifier transformer 5, The negative output terminal is connected to the rail 6. A freewheeling diode 7 with the polarity shown is connected between the positive and negative output terminals of the silice rectifier 4. In the device configured as described above, the output of the diode rectifier 1 When the voltage is ED and the output voltage of the thyristor rectifier 4 is ed, the output voltage Eo' of the DC substation is Eo' = E
o + e (1 (variable). This output voltage E D/
is applied to the DC bus 3, so that DC power is supplied to an electric car (not shown) located under the overhead contact line connected to the DC bus 3. Here, the output voltage ed of the silice rectifier 4 is controlled as shown in the characteristic diagram of FIG. 4 according to the load factor of the electric vehicle. In Fig. 4, when no load is applied, ed=
0, the DC bus voltage (EDB) becomes equal to the output voltage IEoo of the diode rectifier 1. The output voltage of the diode rectifier 1 decreases as shown by a straight line a as the load factor of the electric vehicle increases, and the phase of the silice rectifier 4 is controlled as shown in the hatched area ed' according to the load factor.

This makes it possible to control and shift the DC bus voltage (EDB) to Ed until 100% load IR, as shown by straight line q. This compensates for the voltage drop in the overhead contact line connected to the DC bus 3.

D1 Problems to be Solved by the Invention The above-described power supply method has the disadvantage that the power factor decreases and harmonic currents are generated because the phase of the thyristor rectifier 4 is controlled. Further, there is a problem in that DC side voltage waveform distortion increases and a smoothing circuit is required. Furthermore, the Sirisk rectifier transformer 5 connected to the same power supply must be installed separately from the diode rectifier transformer 2 (on the primary side of the transformer 2) to avoid the influence of voltage waveform distortion caused by the diode rectifier 1. be. Therefore, the equipment of the transformer 5 and the silice rectifier 4 becomes large-sized, and the cost of the equipment becomes extremely high.

The present invention has been made in view of the above points, and provides a power supply method for a DC electric railway that eliminates the need for phase control of a forward power converter, prevents a drop in power factor and harmonics, and reduces the cost of the device. is intended to provide.

Means and operation for solving the E1 problem The present invention has the following features:
In the power supply method of DC electric railways, which converts AC power derived from a commercial frequency power supply into DC and supplies it to electric cars existing under the DC overhead contact line, within the operating range from no load to a predetermined load factor, the power of the commercial frequency power supply is AC power is converted to DC by a first forward power converter without an output voltage control function and is supplied to an electric car under the DC overhead contact line, and within an operating range where the load factor is higher than the predetermined load factor, the AC power of the commercial frequency power source is A second forward power converter which has DC conversion and is not phase-controlled is operated, and the output power of the second forward power converter and the output power of the forward power converter 1 subordinate to the 13th are added to obtain the above-mentioned result. It is characterized by supplying electric cars under the DC power line.

F. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the same parts as in FIG. 3 are shown with the same reference numerals, and their explanation will be omitted. FIG. 1 shows a power supply device for carrying out the power supply method of the present invention, and reference numeral 11 denotes a first forward power for converting AC power led from a commercial frequency power source (not shown) through a transformer 12 into DC. A converter, for example, composed of a diode rectifier without output voltage control function.

The negative output end of this diode rectifier ill is connected to the rail 6. The positive output terminal of the diode rectifier H is the second
It is connected to the negative side output terminal of a forward power converter, for example, a sirisk adjuster 14. The positive output end of the silice rectifier 14 is connected to the DC bus 3 to which an unillustrated overhead contact line is connected. The AC input side of the thyristor rectifier 14 is connected to the secondary side of the transformer 12 via a transformer a l 5. A diode 17 having the polarity shown is connected between the positive and negative output terminals of the silice rectifier 14. It is assumed that the thyristor rectifier 14 is controlled to turn on and off, but not to control the phase.

Next, the operation of the device made +1'It as described above is
This will be explained along with the voltage characteristic diagram shown in the figure. First, while the load factor of an electric car (not shown) existing under the overhead contact line connected to the DC bus 3 is from no load to a predetermined load factor, for example, 50%, each of the thyristor rectifiers [4] thyristor
Leave H in the off state. As a result, the AC power led through the transformer 'a12 is converted into DC by the diode rectifier 11, and the DC power is supplied via the diode 17 to an electric car (not shown) on the DC bus 3. , at this time, the voltage (Eon) of the DC bus 3 is the diode rectifier 1
It is equal to the output voltage Eo of 1, and decreases as the load factor of the electric vehicle increases. Next, in a region where the load factor is 50% or more, each thyristor TH of the thyrisk rectifier 14 is controlled to be turned on. Then, the DC bus 3 is connected to the transformer I2
The output power of the thyristor rectifier 14 and the output power of the diode rectifier 11 obtained by converting the AC power led through the thyristor rectifier 5 into DC are supplied. Therefore, the DC bus voltage (Eon) changes from the output voltage e of the thyristor rectifier 14 to the voltage Eo at the time of 50% load factor (when the thyristor is turned on).
The voltage is the sum of tl. After that, the DC bus voltage (E
DR) changes along a straight line as the load factor increases, not shown in Eo + ed. Therefore the diode rectifier 11
Output voltage Eo of thyristor rectifier 14 and output voltage 6d of thyristor rectifier 14
By selecting an appropriate value, it is possible to lower the power supply voltage when no load is applied, and also to reliably compensate for the voltage drop when the load factor increases beyond a predetermined value.

The conventional method of controlling the phase of a thyristor rectifier is
When the AC input waveform is distorted, voltage waveform distortion increases due to unbalanced control angles of the thyristors that make up the thyristor rectifier. However, in the embodiment described above, since phase control is not performed, the voltage waveform distortion does not increase. Further, the transformer 15 for the thyristor rectifier 14 can be connected to the secondary side of the transformer 12, so that the structure of the transformer can be miniaturized.

G4 Effects of the Invention The following effects can be obtained by the present invention as described above. 4-Nawashi, (+) It is possible to reliably compensate for the voltage drop in the power line and supply stable DC power.

(2) Eliminates the need for phase control during forward power conversion operation, so
A drop in power factor and generation of harmonics can be prevented, and a voltage waveform with less distortion can be obtained.

(3) Since a phase control device is not required, the entire power supply device is simplified and its reliability is improved.

(4) Since the phase is not controlled, the second forward power converter can be made smaller, and the transformer for the second forward power converter is connected to the secondary side of the transformer for the first forward power converter. This allows the structure of the transformer to be miniaturized. This allows the power supply device to be constructed at low cost.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment in which the power feeding method of the present invention is applied to a power feeding device, Fig. 2 is a voltage characteristic diagram for explaining the power feeding method of the present invention, and Fig. 3 is a diagram of a conventional power feeding device. FIG. 4 is a circuit diagram showing an example, and a voltage-current characteristic diagram showing an example of a conventional power supply method. 3... DC bus, 6... Rail, 11... Diode rectifier, 12.15... Transformer, 14... Thyristor rectifier, 17... Diode. Figure 1 Voltage characteristic factors

Claims (1)

[Scope of Claims] In a power supply method for a DC electric railway that converts AC power derived from a commercial frequency power source into DC and supplies it to electric cars existing under a DC overhead contact line, within an operating range from no load to a predetermined load factor. In this case, the AC power of the commercial frequency power supply is converted to DC by a first forward power converter without an output voltage control function and is supplied to the electric car under the DC overhead contact line. Converting the alternating current power of the frequency power supply to direct current, operating a second forward power converter whose phase is not controlled, and adding the output power of the second forward power converter and the output power of the first forward power converter. A method for supplying power to a DC electric railway, characterized in that the electric current is supplied to electric cars under the DC overhead contact line.