JPH0320891B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a single-phase autotransformer with a tertiary winding. In response to the remarkable growth in electricity demand, Japan's first 500KV power transmission began in 1972, and 1000KV class power transmission is planned in the near future. The transformers used for direct connection between ground systems, such as these 500KV power transmission systems, are single-phase autotransformers in order to be economical and to comply with Japan's strict railway transportation restrictions. Figure 1 shows a wiring diagram of a typical conventional single-phase single-winding transformer, in which a series winding 1, a shunt winding 2, and a tap winding 4 are connected in series, with one end serving as a high-voltage line terminal U. The other end is the neutral point terminal v, and the tertiary winding 3
are provided, and the terminals are used as tertiary terminals a and b, and this tertiary winding 3 and an excitation winding 5 that excites the tap winding 4 are connected.
The tap winding 4 is connected in series to the neutral point side of the shunt winding 2, and the voltage at the low voltage line terminal u drawn out from between the series winding 1 and the shunt winding 2. is kept constant, and the voltage at the high voltage line terminal U is varied. An example of a specific winding arrangement of this type of single-phase autotransformer is shown in FIG. 2. Series 11 and 1 are connected to the two main legs 71 and 72 of the single-phase four-leg iron core, respectively.
2. The shunt windings 21, 22 and the tertiary windings 31, 32 are wound and connected in parallel, and the tap winding 4 is connected to the side leg 70, and the excitation winding is connected in parallel to the tertiary windings 31, 32. 5 is wrapped. According to this connection, the voltage of the excitation winding 5 is low;
Although there is an advantage that the winding configuration is relatively simple, since the voltage at the high-voltage line terminal U is varied by tap switching on the neutral point side, the excitation of the iron core changes depending on the tap position, and therefore the tertiary The disadvantage is that the voltage fluctuates. For example, 500KV/√3− actually used
In the case of a single-phase single-turn transformer with a tertiary winding of 275KV/√3-63KV, the core excitation voltage ratio at each of the highest tap, rated tap, and lowest tap is 252.7KV (=
527.7−275): 225KV (=500−275): 202.7KV (=
477.7−275). Therefore, the tertiary voltage varies greatly from 70.8KV to 63KV to 56.8KV at each tap. Generally, a capacitor or reactor is connected to the tertiary terminal to adjust reactive power, so if the terminal voltage changes significantly depending on the tap position as described above, the utilization rate of the capacitor etc. will decrease and reactive power control will become complicated. The problem arises. In order to keep the tertiary terminal voltage constant, a series transformer 6 was installed in the middle of the tertiary circuit as shown in Figure 3.
A method has been proposed in which this is excited from the tap winding 4 and the voltage change in the tertiary winding 3 is compensated for by the voltage change in the series transformer 6. However, in reality, this method has not been adopted until now because it requires a separate series transformer 6 as mentioned above, which increases the installation space and complicates the wiring, which is unfavorable for the reliability of the equipment. Not yet. As mentioned above, conventional autotransformers with tap switching on the neutral point side have the disadvantage that the tertiary voltage varies depending on the tap position, making operation complicated. The present invention eliminates the drawbacks of conventional autotransformers as described above, and provides an improved single-phase autotransformer with a tertiary winding that does not change the tertiary voltage due to taps and does not require a large installation space. The purpose is to provide the following. An embodiment of the present invention will be described below with reference to FIGS. 4 and 5. FIG. 4 is a wiring diagram of a single-phase single-winding transformer with a tertiary winding according to the present invention, in which a series winding 1, a shunt winding 2 and a tap winding 4 are connected in series, with one end connected to a high-voltage line terminal U. and the other end is the neutral point terminal v. A low voltage winding 8 is provided which is connected between a low voltage line terminal u drawn out from between the series winding 1 and the shunt winding 2 and a neutral point terminal v, and the tertiary winding is performed by this low voltage winding 8. The wire 3 is energized. The tertiary winding 3 is connected in parallel with an excitation winding 5 that excites the tap winding 4. FIG. 5 shows an embodiment of the winding arrangement of a single-phase single-turn transformer with a tertiary winding according to the connection shown in FIG. Series winding 1 on the first main leg 71 of the single-phase four-leg iron core
A shunt winding 2 is wound around the second main leg 72, and a low voltage winding 8 and a tertiary winding 3 are wound around the second main leg 72. A tap winding 4 connected to the neutral point side of the shunt winding 2 and an excitation winding 5 connected in parallel to the tertiary winding 3 are wound around one side leg 70. However, in the single-phase single-turn transformer with a tertiary winding according to the present invention, the tertiary winding 3 is excited by the low-voltage winding 8 that keeps the voltage constant, so the voltage varies depending on the position of the tap. It never changes. Furthermore, since the voltage of the tertiary winding 3 is kept constant, the induced voltage of the tap winding 4 excited by this tertiary winding 3 also becomes constant, but the induced voltage of each winding due to this is as described above. In the case of an autotransformer with a voltage rating as shown in Table 1, the voltage at each tap of the high voltage line terminal U is the maximum tap 525KV/√3,
Rated tap 500KV/√3, minimum tap 475KV/
√3 has the advantage that the voltage change width is constant on the positive side and negative side, making it easier to operate the transformer.

[Table] The conventional third method for making the tertiary voltage constant
Compared to the configuration shown in the figure, a series transformer is not required, so the wiring and configuration are simplified. In addition, since the windings wound around the main landing gear 71 are only the series winding 1 and the shunt winding 2, as shown in FIG. 5, the two sets of series windings shown in FIG. Even if the wires 11, 12 and the shunt windings 21, 22 are made into one set and concentrated on the main landing gear 71, the diameter of the winding does not become extremely large, and manufacturing can be done within the transport limit. Become. In addition, if the transformer capacity increases and the winding diameter becomes too large if series and shunt windings are concentrated around the main leg 71, a single-phase five-leg iron core with an increased number of main legs may be used. 5, and the series and shunt windings may be divided and wound around two of the main legs in the same configuration as the main leg 71 of FIG. 5. Although the windings shown in FIG. 5 are arranged on each leg of the same single-phase four-leg iron core, the present invention is not limited to this. For example, tap windings 4
The excitation winding 5 and excitation winding 5 may be wound around another core to form a so-called on-load voltage regulator, or in this case, the core of the main transformer may be a single-phase three-legged core connected in series to the main leg. The winding 1 and the shunt winding 2 may be wound, and the low voltage winding 8 and the tertiary winding 3 may be wound around the side legs. In particular, when winding the tertiary winding 3 on the side landing gear, the number of turns is approximately twice that of winding it on the main landing gear, but as a result, the tertiary winding 3 and the low voltage winding 8
This also has the effect of increasing the impedance by approximately four times, which is advantageous in keeping the tertiary shunt capacitance small. Furthermore, if weight restrictions are strict due to transportation to mountainous areas, it is also possible to wind the tertiary winding and low voltage winding on separate iron cores. In the above explanation, all single-phase converters were used, but for example, if the tap part is used as the above-mentioned separate load voltage regulator, it is also possible to use this as a three-phase converter. It is clear that the 8 portions of the winding wire can be constructed as another three-phase transformer, and that either method has exactly the same effect as the present invention. As explained above, according to the present invention, the tertiary voltage can be kept constant regardless of the tap position, and a small and economical single-phase single-turn transformer with a tertiary winding can be obtained. .

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a conventional single-phase single-winding transformer with a tertiary winding, Figure 2 is a configuration diagram showing an example of the winding arrangement, and Figure 3 keeps the tertiary voltage constant regardless of the tap position. Figure 4 is a wiring diagram of the single-phase autotransformer with tertiary winding of the present invention, and Figure 5 is its winding arrangement. It is a block diagram showing an example. Explanation of symbols, 1, 11, 12...Series winding,
2, 21, 22...Shunt winding, 3, 31, 32...
...Tertiary winding, 4...Tap winding, 5...Excitation winding, 6...Series transformer, 71, 72...Iron core main leg, 70...Iron core side leg, 8...Low voltage winding, U ……
High voltage line terminal, u...low voltage line terminal, v...neutral point terminal, a, b...tertiary terminal.

Claims (1)

[Claims] 1. A series winding and a shunt winding are wound around the first main leg of a single-phase four-leg iron core, and a low voltage winding and a tertiary winding are wound around the second main leg, One side leg is wound with a tap winding connected in series to the neutral point side of the shunt winding and an excitation winding connected in parallel to the tertiary winding, and the low voltage winding is connected at both ends thereof. are connected in parallel to terminals on both sides of the shunt winding and the tap winding. 2. A single-phase single-turn transformer with a tertiary winding according to claim 1, characterized in that the tap winding and the excitation winding are wound on separate core legs. 3 A series winding and a shunt winding are wound around the main legs of a single-phase three-legged iron core, a low voltage winding and a tertiary winding are wound around one side leg, and the shunt winding is wound around the other iron core leg. A tap winding connected in series to the neutral point side and an excitation winding connected in parallel to the tertiary winding are wound, and both ends of the low voltage winding are connected to the shunt winding and the tap winding. A single-phase autotransformer with a tertiary winding characterized by parallel connection to terminals on both sides. 4 In what is stated in claim 3,
A single-phase autotransformer with a tertiary winding, characterized in that the low voltage winding and the tertiary winding are wound on separate iron core legs. 5 A series winding and a shunt winding are wound around the main legs of a single-phase three-leg iron core, and one side leg has a tap winding connected in series to the neutral point side of the shunt winding, and an excitation winding. The wire is wound, and the low voltage winding and tertiary winding are wound around another core leg.
The low voltage winding has both ends connected in parallel to both terminals of the shunt winding and the tap winding, and the tertiary winding is connected in parallel to the excitation winding. winding transformer.