JPS584445B2 - Hentatsuki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a transformer with an on-load tap changer and having three windings: a series winding, a shunt winding and a tertiary winding.

Conventionally, in a three-winding transformer with an on-load tap changer, the tap winding is connected to only one winding, and it is rare that the voltage of the second or third winding must also be adjusted.

However, recently in 500KV single-phase autotransformers,
In many cases, a tap winding is provided on the neutral point side for the purpose of increasing the transport capacity of the main body while it is assembled.

FIG. 1 is a wiring diagram showing an example of this, where U is a high-voltage line terminal and U is a medium-voltage line terminal, which are drawn out from the middle of the winding of an autotransformer.

The portion of winding 1 is a series winding, and the portion of winding 2 is a shunt winding.

The winding 3 is a tertiary winding, and terminals a and b are triangularly connected externally.

4 is a tap winding installed on the middle point side of the shunt winding, that is, on the V terminal side which becomes the neutral point side terminal when connected to two other single-phase transformers in a three-way star shape. For example, the medium voltage line end voltage is kept constant and the high voltage line end voltage is adjusted.

5 is an excitation winding of the tap winding 4. In such a transformer, when the capacity of the transformer increases, the main winding section consisting of the series winding 1, shunt winding 2, and horizontal winding 3 is wound in parallel around two or three iron core legs, and the tap winding 4 is wound in parallel around two or three iron core legs. In most cases, two to three parallel circuits are connected to the other leg or a separate iron core in correspondence with the number of parallel circuits in the main winding.

This means that if you do this, the impedance of each parallel circuit will be the sum of the impedance of the main winding section and the impedance of the tap winding section, and the 4 sections of the tap winding, including the tap changer section, will cause the cut-off time of the tap changer to vary. Since the impedance of the main winding part is large, the current is divided equally without causing any unbalance in the overall impedance, and the cut-off current of the tap changer is also reduced by 1/2 to 1/2. 3, so a small tap changer can be used.

FIG. 2 is a wiring diagram in which six main windings are connected in three circuits in parallel, and a tap winding is connected to each main circuit.

In the figure, 11 to 13 are series windings, 21 to 23 are shunt windings, and 3
1 to 33 are tertiary windings, and 41 to 43 are tap windings.

In this way, in the case of an autotransformer with a neutral point tap switching system in which the tap windings 41 to 43 are provided on the neutral point side, the induced voltage per turn of the winding changes by changing the taps. The voltage of the tertiary windings 31 to 33 also fluctuates.

This is clear from the fact that if we consider the case where the voltage at the end of the high-voltage line is kept constant and the voltage at the end of the high-voltage line is varied, the voltage induced in the series winding changes.

The fluctuation range of the induced voltage per turn is determined by the voltage adjustment range of the tap, and if this is large, the fluctuation of the tertiary voltage will also be large, which is not preferable for electrical equipment to which the tertiary windings 31 to 33 are connected.

Therefore, as a method of compensating for fluctuations in the tertiary voltage, a series transformer 6 is connected between terminals b and b' in series as shown in Figure 3.
'A method of inserting a voltage adjustment transformer 7 is considered.

In the figure, 61 is a main winding, and 62 is an excitation winding.

Furthermore, the voltage regulating transformer 7 may be omitted by using the tap winding 4 instead of the voltage regulating transformer 7.

The connection diagram is as shown in Figure 4. However, if the six-tap windings 41 to 43 are structured in parallel with three circuits as shown in Figure 2, and it is necessary to divide the current equally into each parallel circuit,
As shown in the figure, the excitation winding 62 of the series transformer 6 is also all 3
The circuit must be configured in parallel.

This is because when the excitation winding 62 has one circuit configuration, the connection point pol between each shunt winding 21 to 23 and the tap winding 41 to 43
, PO21Poa are connected to each other.

Therefore, the current flowing through the circuit on the neutral point side from this connection point, that is, the tap winding part, is determined only by the impedance of the tap winding part, so if there is a resistance imbalance in each parallel circuit of the tap winding part, the current flows evenly. This is because it is not diverted.

Therefore, in such a case, although there is an advantage that the voltage regulating transformer 7 can be omitted, the structure of the excitation winding 62 of the series transformer 6 becomes complicated, and the lead 81 connecting the tap windings 41 to 43 and the excitation winding 62 becomes complicated. There are drawbacks such as the large number of ~84.

This invention was made in view of the above circumstances, and it is possible to simplify the winding of a series transformer without impeding the current shunting effect of the tap winding due to the impedance of the main winding, and to reduce the number of connecting leads. The purpose is to provide a transformer that can reduce the power consumption.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 shows an embodiment of the present invention, in which the series winding 1
1 to 13, shunt windings 21 to 23, tertiary windings 31 to 33, tap windings 41 to 43, and their excitation windings 5 are the same as in FIG. 5, but the configuration of the series transformer 6 is different. Ru.

That is, the series transformer 6 is used to compensate for voltage fluctuations in the tertiary winding, but the main winding 61 is connected in series between the terminals b and b', and the excitation winding 62 is connected to one tap winding 43 of tap windings 41 to 43 consisting of three parallel circuits.

In the transformer configured like this, shunt windings 21 to 2
3, the current flowing through each of the tap windings 41 to 43 is equal to 11, and the current flowing through the excitation winding 626 of the series transformer 6 is 12.

Then, a current of 11+12 flows through the tap winding 43 connected to the excitation winding 62.

Therefore, since the current of 11 is less than the current capacity of the tap changer, this wiring system can be adopted if the current of 11+12 is less than the current capacity of the tap changer.

Of course, if the current capacity of the tap changer is exceeded, it is only necessary to change the entire tap changer or only the tap changer to which tap windings 43 are connected. In many cases, a tap changer with a smaller interrupting current capacity is required than when the current is not shunted.

On the other hand, if the excitation winding is configured as one circuit and connected to all tap windings 41 to 43 consisting of three parallel circuits, the current 11 flowing from the shunt winding to the tap winding and the excitation winding 62 are Since the flowing current 12 may not be shunted through the three parallel circuits, and in the worst case may flow through one tap winding circuit 311+12, a tap changer with a cutoff current capacity of 311+12 must be prepared.

Also, as shown in FIG. 6, one excitation winding 62 of the series transformer 6
Since only one circuit of the tap winding 43 connected in parallel with is connected, the number of connecting leads 81 and 84, which conventionally required four, can be reduced to two. The line structure can be simplified, and the series transformer can be made smaller accordingly.

FIG. 7 shows another embodiment of the present invention, in which the excitation winding 62 of the series transformer 6 has a two-circuit parallel configuration, and each tap winding 41 to 43 has a three-circuit parallel configuration. The difference from FIG. 6 is that two of the circuits are connected correspondingly.

In the configuration shown in Figure 6, when the current of 11 + 12 exceeds the current capacity of the tap changer, 6 If such a configuration is adopted, the current flowing through the two parallel circuits of the excitation windings of the series transformer will be 12/ 2, the current flowing through the tap winding connected to the excitation winding can be reduced by i1+i2/2, making it less than the current capacity of the tap changer.

Furthermore, the currents 11 and 12 are not necessarily currents in the addition direction, and many currents are in the subtraction direction.

In such a case, the current in the tap winding will decrease, so there is no risk of exceeding the current capacity of the tap changer.

In addition, if the current in the tap windings 41 to 43 connected to the excitation winding 62 of the series transformer 6 exceeds the current capacity of the tap changer, it can be reduced by increasing or decreasing the compensation range for tertiary voltage fluctuation. is also possible.

FIG. 8 shows another embodiment of the present invention, in which a main winding and a tap winding are made up of series windings 11 and 12, shunt windings 21 and 22, and tertiary windings 31 and 32. 41.42
has a two-circuit configuration, and only one of the tap windings is electrically connected to the excitation winding 62 of the series transformer 6.

Even in the structure configured in this way, the above-mentioned inverse effect is exerted, and the structure can be deformed depending on the magnitude of the above-mentioned inverse current ix+12.

As described above, the present invention provides a method for connecting only a portion of the number of circuits of the tap winding to the excitation winding of the series transformer in a tap winding having two or more parallel circuits. Therefore, it is possible to provide a transformer in which the winding of a series transformer can be simplified and the number of connecting leads can be reduced without impairing the current shunting effect of the tap winding due to the impedance of the main winding.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a single-phase single-winding transformer with the tap winding on the neutral point side, Figure 2 is a wiring diagram when the main winding of Figure 1 is connected to three circuits in parallel, Figure 3 and Fig. 4 is a wiring diagram showing the method of compensating the tertiary voltage shown in Fig. 1, Fig. 5 is a wiring diagram when the three circuits shown in Fig. 4 are connected in parallel, and Figs. 6 to 8 are each of this invention. It is a wiring diagram of different transformers. 11-13...Series winding, 21-23...
...Shunt winding, 31-33...Tertiary winding, 41
~43...Tap winding, 6...Series transformer having main winding 61 and excitation winding 62.

Claims (1)

[Claims] 1. By exciting the excitation winding of the series transformer connected to the terminals of the secondary or tertiary winding with the voltage generated in the tap winding provided to adjust the voltage of the primary winding, the voltage of the secondary winding is adjusted. Alternatively, in a transformer that adjusts the voltage of a tertiary winding, the tap winding is composed of two or more parallel circuits, and the series connection is performed using only a part of the number of circuits of the tap winding. A transformer designed to excite the excitation winding of a transformer.