JPS59123214A - Auto-transformer - Google Patents

Abstract

PURPOSE:To obtain a large capacity auto-transformer whose tertiary terminal voltage does not change regardless of the tap position and is easy to use by a method wherein two series windings and two shunt windings in the 1st tank are respectively connected in parallel and moreover, the tertiary winding and an exciting winding in the 2nd tank, and a series winding of a series transformer and a series winding of a main transformer are respectively connected by leads. CONSTITUTION:The voltage applied to the terminals (u), (v) of shunt windings 2a, 2b is the voltage of medium voltage side and constant, so excitation of a core does not change regardless to the tap position. Thus, the terminal voltage of the tertiary winding 3 is also constant regardless to the tap position accordingly. Then the voltage of high voltage side is a summation of the induced voltage of series windings 1a, 1b and shunt windings 2a, 2b, which induce a constant voltage, and the induced voltage of series winding 11 of a series transformer 63, which induces variable voltage in accordance with the tap position, and can be adjusted to a required value by selecting a voltage of a tap winding 4 and the turns ratio of two windings 51 and 11 of the series transformer 63. The construction of the main transformer is simple because the tap winding 4 and the series transformer 63 are not housed in the same tank.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in autotransformers.

[Technical background of the invention and its problems]

In response to the recent remarkable growth in electricity demand, 500kV power transmission began in Japan about 10 years ago, and 1000kV class power transmission is also planned in the near future. By the way, autotransformers are used as transformers for linking these directly grounded systems for economical reasons, but these For this reason, it is generally manufactured and transported as a single-phase unit and operated locally as a three-phase unit.

FIG. 1 is a wiring diagram showing a typical conventional single-phase autotransformer with two parallel main winding legs. In the figure, Iaylb is a series winding, 2a and 2b are shunt windings, 3 is a tertiary winding, 4 is a tap winding, 5 is an excitation winding, and tap winding 4 is a shunt winding 2a.

2b is connected in series to the neutral point side to keep the voltage at the medium voltage line terminal U constant and to vary the voltage at the high voltage line terminal U.

Incidentally, although the autotransformer with such a wiring configuration has the advantage that the voltage of the excitation winding 5 is low and the winding configuration is relatively simple, the high-voltage line terminal U is connected by flage switching on the neutral point side. There is a drawback that the excitation of the iron core for varying the voltage varies depending on the position of the tap, and therefore the voltage between terminals a and b of the tertiary winding 3 also varies. for example,
Actually used 500/v”J kV 27
5/v"3; Taking a single-phase autotransformer with a kV tertiary winding as an example, the voltage ratio for the highest tap, rated tap, and lowest tap is 527.5/V'T kV -275 Mu α
kV, 500/J'J kV -275/V'T
kV, 477.77-y”i kV 275/J
It is named rkV. Therefore, the rated voltage is 63
If it is kV, the voltage between tertiary terminals a and b is high.

The rated and lowest taps are each 70.8kV.

63 kV and 56.8 kV, which vary considerably.

Generally, a capacitor or an accelerator is connected to the tertiary terminals a+b to adjust the reactive power, so if the tertiary voltage fluctuates significantly depending on the tap position as described above, the utilization rate of the capacitor etc. will decrease, and the reactive power will decrease. Problems such as complicated control arise.

Therefore, in order to keep the tertiary terminal atb voltage constant, a series transformer 61 is provided in the middle of the tertiary circuit as shown in FIG. A method of compensating by changing the voltage of the device 61 has been proposed so far. However, with this method, if you want to increase the voltage adjustment range of the high-voltage line terminals for operational reasons, the excitation rate of the iron core will change drastically, and the transformer will become larger and its weight will also increase. Therefore, there are restrictions on its application.

For example, 500 m/T kV -275/-1"g k
The voltage adjustment range of the high-voltage line terminal U is 10 with an autotransformer of V.
07v'TkV, the terminal voltage is 560.6/v/'(2
75/-1'JkV, 500/J7 kV 2te5
△('l, 460.67-J"; kV-275/
JXkV Tonashi 1. The tertiary terminal voltage is also 80.0k each.
V, 63kV, and 52kV. Therefore, IP is when the excitation rate of the iron core is at its highest tap.

Assuming U, the rated tap is 0.89P, and from U to 0
．． 79P, U, which is small, requires the use of a lower core excitation, lowering the utilization rate and requiring the use of a thicker core. That is, if the main transformer itself is heavy, it is possible that the transport limit may be exceeded.

In addition, as a well-known method for preventing excitation fluctuations in the iron core, as shown in Figure 3, a tap winding 4 is wound around one main leg of the iron core, and a series transformer 62 is energized from this to indirectly There is a method of varying the high or medium voltage. However, this method is used for low-voltage, small-capacity vessels with relatively few transportation restrictions, but transportation restrictions are severe for ultra-high-voltage class large-capacity vessels, and in order to ensure reliability, this method is used for loads with moving parts as much as possible. There are few practical examples in Japan due to the strong desire of users not to incorporate a time tap changer into the main body.

As mentioned above, conventional high-voltage autotransformers have the drawbacks of fluctuations in tertiary terminal voltage, and indirect tag switching type transformers have severe transportation restrictions and insufficient reliability of the main unit. be.

[Object of the Invention] The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a highly reliable device that does not change the tertiary terminal voltage depending on the tap position and is easy to use and transport. The purpose of the present invention is to provide a large-capacity autotransformer.

[Embodiments of the invention]

An embodiment of the present invention shown in the drawings will be described below.

FIG. 4 is a wiring diagram showing an example of the configuration of a single-phase autotransformer according to the present invention, and is shown in conjunction with FIGS. 1 to 3. In the figure, one main leg series winding 1 of an iron core with two main legs
The main transformer body, which consists of winding a1 shunt winding 2a, winding series winding 1b, shunt winding 2b', and secondary windings a and 3 around the other main leg, is housed in one tank A, A voltage regulator in which an excitation winding 5 connected in parallel with the tertiary winding 3 and a tap winding 4 are wound around the iron core leg, and a series winding wound around the iron core leg in pairs with a winding 51 excited from the tag winding 4. The series transformer 63 with wire 11 is housed in another tank B, and the series windings 1a and 1 in tank A are
b and the branch series windings 2a and 2b are respectively connected in parallel,
Furthermore, the leads of the tertiary winding 3, the excitation winding 5, the series winding 11 of the series transformer 63, and the series windings 1a and 1b of the main transformer are connected through an oil-submerged duct or the like. Note that U is a high voltage line terminal, U is a medium voltage line terminal, and a and b are tertiary terminals.

Next, the functions and effects of the autotransformer having such a configuration will be explained. In FIG. 4, since the voltage applied between both terminals u and v of the shunt windings 2a and 2b is constant on the medium voltage side, the excitation of the iron core does not change depending on the tap position. Therefore, the terminal voltage of the tertiary winding 3 is also constant regardless of the tag position. Next, the voltage on the high voltage side is the series windings 1a and Ib and the shunt winding 2a, which induce a constant voltage.

2b and the induced voltage of the series winding 11 of the series transformer 63 whose induced voltage changes depending on the tap position. By selecting the turns ratio, it is possible to adjust the voltage to the required value. In addition, since the main transformer does not house the tap winding 4 and the series transformer 63 in the same tank, the configuration is simple and reliability is improved. Can be made larger. On the other hand, since the tap changer and tap winding 4 are housed in a tank separate from the main transformer, even in the unlikely event of an accident with the tap changer, the spread of the accident to the main transformer can be reduced. can. In addition, in the configuration shown in Fig. 4, the medium voltage line U is drawn out from the tank A on the main transformer side, so in the event of the above accident, the medium voltage leads of the series windings 1a and 1b and the lead from the medium voltage line terminal U If connected in tank A, tank B can be easily disconnected and operated using only the main transformer.

Next, FIG. 5 is a wiring diagram when the present invention is applied to a three-phase autotransformer, showing the three phases of FIG. 4. In the figure, the tertiary winding 3 is connected in a triangular (△) manner, but the connections for each phase are similar to those in FIG. 4. Note that the terminal symbols are for three-phase equipment, so U, V, and W are high-voltage line terminals for each phase, u,
v and W are medium voltage line terminals for each phase, and a, b, and c are tertiary terminals for each phase. It is clear that even in the configuration shown in FIG. 5, the same effects as in the above embodiment can be obtained, with only the difference between single phase and three phase.

In the case of the one in Figure 5, depending on transportation restrictions, the main transformer side may be housed in a separate tank as a unit single-phase transformer having a series winding, a shunt winding, and a tertiary winding, and the voltage adjustment It is clear that similar effects can be obtained even if the transformer and the transformer of tank B housing the series transformer are combined.

In addition, 1 In each of the above embodiments, the tank A is formed by an oil submerged duct.
The lead connection between and 2728 may be made in the air,
Needless to say, it is also possible to use a structure in which the oil between the two tanks is partitioned through an oil-immersed wall bushing or the like.

〔Effect of the invention〕

As explained above, according to the present invention, the tertiary terminal voltage can be kept constant regardless of changes in the tap position, and a highly reliable large-scale battery that is easy to use and transport, and can be easily handled in the event of an accident. Capacity autotransformers can be provided.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram showing a conventional single-phase auto-transformer, Fig. 2 is a wiring diagram showing a single-phase auto-transformer with a series transformer inserted in the tertiary circuit, and Fig. 3 is a wiring diagram showing a series transformer in the tertiary circuit. A wiring diagram showing a single-phase single-winding transformer inserted into a voltage circuit and having a tag winding wound around the iron core leg of the main transformer. Figure 4 is a wiring diagram showing an embodiment of the present invention. Figure 5 is a wiring diagram of the main transformer. FIG. 3 is a wiring diagram showing another embodiment of the invention. la, Ib...Series winding of main transformer, 2a. 2b...Shunt winding, 3...Tertiary winding) 4...Tap winding, 5,51...Excitation winding, 11...Series winding of series transformer, 6 Z , 62, 63-... Series transformer, U. V, W... High-voltage line terminal, u, v/W... Medium-voltage line terminal, v'... Neutral point side terminal of single-phase transformer , 0...neutral point side terminal of three-phase converter, A, B...tank, D...submerged oil duct.Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 0- Figure 4 I: Io 11

Claims (2)

[Claims] (1) A first core having two main legs, a first and a second main leg.
A main transformer main body consisting of a series winding and a shunt winding wound around the main leg and a series winding, a shunt winding and a tertiary winding wound around the second main leg is housed in the first tank, A voltage regulator body in which a first excitation winding and a tap winding are wound around an iron core leg, and a series firing in which a second excitation winding excited from the tap winding and a second series winding are wound around an iron core leg. The pressure vessel is housed in a second tank, and the pressure vessel is housed in the first tank. The series windings and shunt windings wound around the second main leg are connected in parallel, the tertiary winding and the first excitation winding are connected in parallel, and the second series winding is One terminal is connected to each of the shunt windings connected in parallel as a medium-voltage line terminal, and the other terminal is connected to the shunt winding connected in parallel in the first tank as a medium-voltage line terminal opposite to the high-voltage line terminal of each of the series windings. An autotransformer characterized by being connected in series to voltage line terminals. (2) The autotransformer according to claim (1), wherein the main body accommodated in the first tank and the second tank has a three-phase configuration.