JP2549194B2 - Voltage fluctuation compensator for feeder circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a voltage fluctuation compensating device for a feeder circuit.

(Prior art) To supply power to AC electric vehicles such as the Tokaido Shinkansen, install a three-winding transformer for feeders at a substation for electric railways, and an autotransformer (AT) on feeder lines. It is carried out by AT feeding system.

FIG. 4 shows the structure of a conventional feeder circuit, 1 is a three-phase power source, 2 is a power source impedance (Zo), 3 is a Scott transformer for three-winding feeder, 3A and 3B are the transformers 3 described above. Got from T
In the single-phase circuit of Zodiac and M seat, for example, in case of Tokaido Shinkansen
Power is supplied from Tokyo to the single-phase circuit 3A and to Osaka from the single-phase circuit 3B.

4 is the leakage impedance of the transformer 3 (ZT, ZN, ZF),
5 is the autotransformer AT, 6 is the leakage impedance (ZAT) of the autotransformer AT, 7 is the train, Z is the load impedance of the train (Z), T, R and F are the trolley wire, rail and feeder, respectively. Show.

FIG. 5 shows the equivalent circuit of one seat extracted from FIG.

In the figure, 1'is a single-phase equivalent power supply, 2'is a power impedance converted into a single phase, and 3'is a single-phase equivalent three-winding transformer.

Here, the voltage of the power supply 1'is Vo, the voltage of the transformer 3'is V1,
If the voltage of the autotransformer AT is VAT, the currents flowing in the T-phase, F-phase, and the neutral point of the transformer are IT, IF, IN, and the load current flowing in the electric train 7 is I, then Each formula holds.

I = IT + IF (1) Vo-V1 = Zo (IT + IF) (2) V1-VAT = ZT ・ IT-2ZAT ・ IF + ZN (IT-IF)
(3) V1-VAT-ZN (IT-IF) + 2ZAT / IF + ZF / IF
(4) VAT = Z · I + 2ZAT · IF (5) IN = IT−IF (6) From the equations (1), (3), (4) and (6),
Then, the following equation is obtained.

IT = (4ZAT + 2ZN + ZF) / Δ · I (7) IF = (2ZN + ZT) / Δ · I (8) IN = (4ZAT + ZF−ZT) / Δ · I (9) However, Δ = 4 (ZAT + ZN) + ZT + ZF Therefore, ZAT = 0 and ZF = ZT, IT
= IF, and the utilization factor of the three-winding transformer 3 becomes 100%.

(Problems to be solved by the invention) However, in such a configuration, ZN = 0, ZF = ZT
However, since it is possible to manufacture ZAT = 0, it follows that IT ≠ IF and the utilization factor of the three-winding transformer 3 decreases.

The voltage drop (V1-ZI) to the load point voltage is
From Eqs. (3) and (5), V1−ZI = ZT · IT + ZN (IT−IF), and the impedance drop (ZT · IT) becomes IT, IF
The component {ZN (IT-IF)} resulting from the unbalance of is added, resulting in a large voltage drop.

It is an object of the present invention to balance the current on the trolley wire side and the current on the feeder line side to increase the utilization factor of the three-winding transformer and to compensate the voltage drop at the load point due to the train load current. .

(Means for Solving the Problem) The present invention connects a trolley wire side compensating power source and a feeder line compensating power source in series with each of the feeding side windings of a Scott transformer for three winding feeding. However, the magnitudes of the voltages of the compensation power supplies are controlled so that the neutral point current flowing through the rail becomes zero.

(Operation) FIG. 2 shows a configuration in which a trolley wire side compensating power source and a feeder line compensating power source are connected to the configuration shown in FIG.

In the figure, 8 is a trolley wire side compensating power supply, and 9 is a feeder line compensating power supply. When the voltage of the trolley wire side compensating power supply 8 is Vt and the voltage of the feeder side compensating power supply 9 is Vf, the following equation is established in the circuit of FIG.

I = IT + IF (10) Vo-V1 = Zo '(IT + IF) (11) V1 + Vt-VAT = ZT.IT-2ZAT.IF + ZN (IT-IF)
(12) V1 + Vf−VAT = −ZN (IT−IF) + 2ZAT ・ IF + ZF ・
IF (13) VAT = Z · I + 2ZAT · IF (14) IN = IT−IF (15) From equations (10), (12), (13) and (15), IT, IF, IN
Then, the following equation is obtained.

IT = {(2ZN + ZT) · I− (Vt−Vf)} / Δ (16) IF = {(4ZAT + 2ZN + ZF) · I + (Vt−Vf)} / Δ (1
7) IN = {(4ZAT + ZF−ZT) · I + 2 (Vt−Vf)} / Δ
(18) However, Δ = 4 (ZAT + ZN) + (ZF + ZT) where IN = 0, Vt−Vf = (4ZAT + ZF−ZT) / 2 · I (19) is set as 0. ) On the other hand, by adding the equations (12) and (13), the following equation is obtained.

Vt + Vf = ZT • IT + ZF • IF-2 (V1−VAT) (20) When the expressions (10), (11) and (14) are substituted into the expression (20) and rearranged, Vt + Vf = ZT • IT + ZF • IF-2 (Vo-I / Zo'-Z /
I−2VAT · IF) (21) If the load point voltage Z · I is made equal to the power supply voltage Vo, there will be no voltage drop. Therefore, if Z · I = Vo, (2
Equation 1) is as follows.

Vt + Vf = (4ZAT + 4Zo ′ + ZF + ZT) / 2 · I (22) When Vt and Vf are calculated from the equations (19) and (20), the following equation is obtained.

∴Vt / Vf = (ZT + Zo ′) / (4ZAT + ZF + Zo ′) (24) In the equation (24), since ZT, Zo ′, ZAT, and ZF are known values, Vt / Vf is a constant value. Therefore, the voltage at the feeding point of the feeder circuit is detected, Vt and Vf are generated so that this becomes equal to the target voltage value, and at the same time, Vt / Vf becomes a constant value determined by equation (24). If the control is performed, the neutral point current IN becomes zero, the load current is balanced, and at the same time, the voltage drop at the load point can be compensated.

In a normal system, the resistance component of the impedance is sufficiently smaller than the reactance component, so that the load current I may be advanced by 90 ° or delayed by 90 ° as Vt and Vf. Therefore, since it is not necessary to compensate active power, the capacity of the compensator can be small.

(Embodiment) An embodiment of the present invention will be described with reference to FIG. In addition, the same reference numerals as those in FIG. 4 indicate the same or corresponding portions. The compensating series power supplies 7 and 8 in the equivalent circuit shown in FIG. 2 are connected to the neutral point side of the transformer 3.

FIG. 3 shows a specific example configuration of one seat of the transformer 3. Here, voltage-type inverters are used as the series compensation power supplies 8 and 9, and the outputs thereof are sent out by the transformers 10 and 11.

The voltage at the feeding point of the feeder circuit is detected by the voltage transformer 12 and given to the comparator 13. The reference voltage Vref is given to the comparator 13 as a voltage target value, and is compared with the output of the voltage transformer 12 here.

Then, via the control circuit 14 according to the deviation between the two values, the voltage at the feeding point becomes the reference voltage Vref and, at the same time, the neutral point current IN detected by the current transformer 15 becomes 0. , 9 control.

The series compensating power supplies 8 and 9 are connected to the neutral point side of the three-winding transformer 3 in the example of the figure, but even if they are installed on the trolley wire (T) side and feeder line (F) side, The same effect can be obtained.

Further, as an additional function of this device, it is possible to provide an effect as an active filter for shaping the load side voltage waveform distortion.

Although the voltage of the feeder circuit is distorted due to the harmonic current generated by the train and the constant of the feeder circuit, it is desirable that the distortion be small from the viewpoint of reducing inductive interference and affecting the control of the train. On the other hand, the compensation voltage generated by this device is generated by PWM control so that the output voltage matches the reference sine wave voltage so that the output voltage becomes the control target. Therefore, the output voltage can be a sine wave.

That is, although the input side voltage and the circuit current of this device cannot be improved, it is possible to bring the effect of bringing the feeding side train voltage close to a sine wave to stabilize the train control.

In this case, there is a problem that the harmonic current generated by the train passes through the compensating power supply and the output side voltage distortion occurs due to its internal impedance, but the compensating voltage is not generated in open loop with respect to the reference sine wave. By feeding back the output voltage distortion to the PWM control of the compensation voltage, the intended purpose can be achieved.

(Effect of the Invention) As described in detail above, according to the present invention, it is possible to improve the utilization factor of the Scott transformer for three-winding feeding by balancing the power supply on the trolley wire side and the current on the wire side. It is possible to compensate for the voltage drop at the load point due to the train load current.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is an equivalent circuit diagram of a concrete configuration example, FIG. 4 is a circuit diagram of a conventional example, and FIG. It is the equivalent circuit diagram. 3 ... Scott transformer for three-winding feeder, 5 ... Autotransformer, 6 ... Leakage impedance of autotransformer, 7 ... Load (train), 8, 9 ... Series for compensation Power supply, T ... trolley wire, R ... rail, F ... feeding wire,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Miyata 47 Umezu Takaunemachi, Ukyo-ku, Kyoto City, Kyoto Prefecture Nissin Electric Co., Ltd. (72) Inventor Shigeru 47 Umezu Takaunecho, Ukyo-ku, Kyoto Prefecture Electric Machinery Co., Ltd. (56) Reference JP-A-60-163739 (JP, A) JP-B-50-1524 (JP, B1)

Claims (1)

(57) [Claims] 1. A three-winding feeder transformer connected to a three-phase power source, a single-winding transformer provided in a feeder line of the three-winding feeder transformer, and the three-winding transformer. Difference between the series power supply for compensating the trolley wire side and the series power supply for compensating the feeder wire connected to the feeder side of the feeder for the feeder and the voltage at the feeding point of the feeder circuit compared to the reference voltage Comparing means for outputting
Based on the output from the comparison means, the voltages of the both series power supplies are generated so that the voltage at the feeding circuit sending point becomes equal to the reference voltage, and the voltage ratio of the both series power supplies is three turns. A feeder comprising a transformer for wire feeding and each leakage impedance of the autotransformer, and control means for controlling the three-phase power source to a constant value determined by the impedance of the power source converted into a single phase. Voltage fluctuation compensator for circuits.