JPS58225623A - Three-phase autotransformer - Google Patents

Abstract

PURPOSE:To decrease the size of a large capacity transformer and expand a limitation of transportation by winding series windings and shunt winding to the same core and also winding the tap winding, 3rd low voltage winding and excitation winding to the other core and by accommodating them in different tanks. CONSTITUTION:A series winding 1 and a shunt winding 21 are wound to the core legs 51-53 of three-phase single coil transformer and are housed in a tank 61. Moreover, a tap winding 4, a 3rd low voltage winding 3 and an excitation winding 22 are wound to the core legs 54-56 and are housed in the other tank 62. A coil 61 and a shunt winding 2 in this tank 61 are connected in series at the intermediate voltage line end of each phase and the terminal in the neutral point side of shunt winding 21 is connected in series to the winding 4 in the tank 62 through an oil-immersed duct 72. In addition, the one ends of windings 4, 3 and excitation winding 22 within the tank 62 are connected to the intermediate voltage line terminals U, V, W through the duct 72, while the other ends to the neutral point O. Thereby, a large capacity three-phase autotransformer can be formed in a small size and limitation on transportation can also be expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a large-capacity three-phase autotransformer, and aims to reduce the weight and size of the autotransformer, thereby increasing its transport limit capacity.

[Technical background of the invention and its problems]

In ultra-high-voltage power transmission, the capacity of each transformer is increasing, and in substations installed inland, transportation size and weight constraints on railways and roads require dividing the unit into smaller units.
It is well known that transportation restrictions are often being addressed. ) Since insulation reliability is particularly important for these ultra-high voltage transformers, it is desirable to transport the transformer as assembled while maintaining the state verified by factory tests, and then reassemble it at the installation site. If transportation conditions are poor and it is not possible to transport the product as a single unit, the most effective method is to divide it into multiple units, assemble and transport each unit, and then connect them together using oil-filled ducts, etc. on-site as a Sanwaki. It is being

FIG. 1 is a diagram showing the internal structure of a typical three-phase autotransformer. In Fig. 1, around the core legs 51, 52, 53, there are tertiary low pressure windings @31. Three windings, a shunt winding 2 and a mountain winding l, are wound and housed in a tank 61. In addition, the other tank 62 has iron core legs 54, 55.
The excitation winding a32 and the tap winding 4 of each phase are wound and housed around the winding 56. Here, U, V, and W are the high-voltage line terminals for each phase of the series winding, u, y, and w are the high-voltage line terminals for each phase of the shunt winding, 0 is the neutral point terminal, and a, b, and c are the high-voltage line terminals for each phase of the shunt winding. The line terminals of the tertiary low voltage winding are shown. Each phase series winding l in the tank 61 connects to the shunt winding 2 and medium voltage line terminals u and v, respectively.
, w are connected in series, and the neutral point side of the shunt winding is the tank 6
It is connected in series to the tap winding 14 in 2 through an oil-filled duct.

Furthermore, the terminals of the excitation winding 32 for excitation of the tap winding 14 in the tank 62 are connected in parallel to the terminals of the low pressure winding llm31 in the tank 61 via an oil-filled duct 71fil-. In this way, the tap winding does not need to be wound together with the series winding, shunt winding, and tertiary low-voltage winding capacity, so the main transformer in the tank 61 can be made smaller and lighter, and it can be transported. This has the advantage of having fewer restrictions. However, in the case of Figure 1, changing the tap changes the magnetic flux density of the iron core, and the tertiary voltage also changes accordingly, making it impossible to maintain a stable tertiary voltage.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned drawbacks, and provides a three-phase autotransformer that can expand the transport limit of the transformer capacity by having a compact and lightweight configuration even under severe transport restrictions. The purpose is to

[Summary of the invention]

In order to achieve the above objects, the present invention stores an iron core and three-phase series windings and shunt windings wound around the legs of the iron core in one tank, and stores the iron core and its shunt windings in the other tank. A tertiary low voltage winding, a tap winding and an excitation winding for three phases are wound around the iron core leg, and the series winding and shunt winding are connected in series at the intermediate voltage line end, and the tap winding The line is connected in series with the shunt winding between the neutral point of the shunt winding and the neutral point, and is connected between the excitation winding, the end of the medium voltage line, and the neutral point. shall be.

[Embodiments of the invention]

The embodiment of the present invention shown in FIG. 2 will be described below.

In FIG. 2, the iron core and the series winding l and the shunt winding 21 wound around the iron core legs 51, 52, 53 are stored in one tank 61, and the iron core and the iron core legs are stored in the other tank 62. 54, 55, and 56, the tap winding 4, the tertiary low voltage winding 3, and the excitation winding 22t are housed.

The series winding l in the tank 61 and the shunt winding 21it are connected in series at the ends of the medium voltage line for each phase, and the neutral point side terminal of the shunt winding 21 is connected to the tap winding 4 in the tank 62 through the oil-filled duct 72. connected in series via.

Further, the tap winding 1114 in the tank 62 and the excitation winding 22 for excitation of the tertiary low voltage winding 3 are connected at one end to the medium voltage line ends u, v, w K via an oil-filled duct 72, and at the other end. Connected to neutral point O.

Next, the operation of the three-phase autotransformer of the present invention constructed as described above will be explained. As is well known, the major factors that determine the size of a transformer are the capacitance of the winding, that is, its size, and the required insulation separation between that winding and other windings, or between the ground electrode of the iron core, tank, etc. .

Generally, in ultra-super high voltage systems, phase adjustment equipment such as reactors and capacitors are often installed in the system to adjust the power factor and improve system stability. In this case, these reactors and capacitors are connected to the tertiary low voltage winding. There are many. In many cases, the tertiary low-voltage winding capacity is usually required to be about 30 times the primary and secondary capacities.

Further, the capacitance of the tap winding is usually about 10% of the capacitance of the series winding or shunt winding.

Therefore, in the configuration shown in FIG. 1, since there are only the tap winding 4 and the excitation winding 32, which have a small capacity and low voltage, in the tank 62, there are no series windings or shunt windings, which have a large capacity and high voltage. Tank 61 housing the wire and tertiary low voltage winding 31
This is extremely small compared to the previous year, and the structure is unreasonable in terms of expanding restrictions on transformer transportation.

However, as in the present invention shown in FIG.
By connecting the excitation winding 22 to the shunt winding 21, which is a tertiary low-voltage winding and a medium-voltage winding, only the series winding and the shunt winding are left in the tank 61, and the tertiary low-voltage winding is Therefore, the tank 61 can be made smaller by the sum of the dimension from the iron core to the tertiary low voltage winding and the dimension of the tertiary low voltage winding.

Also, if the tank is the same size, the weight of the series winding and shunt winding can be increased.

On the other hand, the tank 62 houses the tertiary low-voltage winding 3, and the excitation winding capacity is larger than in the conventional structure because it is necessary to excite both the tap winding and the tertiary low-voltage winding. Since the winding 22Fi is connected to the shunt winding in the tank 61, the insulation between other windings and from the tank ground electrode must be increased in size, but since the tank 62 was originally smaller than the tank 61, The sizes of both tanks are balanced, allowing optimization of transport dimensions and transport weight. In addition, in the case of the conventional configuration shown in FIG. 1, the tertiary voltage also fluctuates by switching the taps, but in the configuration according to the present invention shown in FIG. 2, the voltage of the excitation winding is equal to the intermediate voltage. It has many advantages, such as constant excitation compared to the high-voltage side voltage adjustment generally adopted by electric power companies, and a constant tertiary voltage can be obtained even when high-voltage tap adjustment is performed.

In the above embodiment, the main transformer housing the series winding and the shunt winding was integrated into a single unit, but in the present invention, each single-phase transformer is housed in a separate tank to increase capacity, and similar connections are made. It is clear that the above-mentioned advantages can be obtained even if

Furthermore, although the excitation winding and the shunt winding are connected through the oil-filled duct that connects both tanks 61 and 62, the intermediate pressure bushings u, y, and w may be pulled out from any tank.

〔Effect of the invention〕

As described above, the present invention combines series windings and shunt windings into
, wrapped around two cores, tap winding, tertiary low voltage winding,
The 3-phase, 3-winding excitation windings are wound around separate iron cores and stored in tanks on each side to form a 3-phase autotransformer, making the large-capacity 3-phase winding transformer smaller and lighter. It is possible to optimize the transport dimensions and expand the transformer transport limit capacity 1, and
A constant tertiary voltage can be obtained regardless of the tap position.

[Brief explanation of drawings]

Figure 1 is a wiring diagram of a typical conventional three-phase autotransformer;
The figure is a wiring diagram of a three-phase autotransformer according to the present invention. l...Series winding 2.21...Shunt winding 3.31...Tertiary low voltage winding 4...Tap winding 22.32...Excitation winding 51.52, 53, 54 ,55.56... Iron core leg 61
62...Tank 71.72...Oil-filled duct FU
, V, W... High voltage line terminals of series windings u, v, w...
・Medium voltage line terminals a, b, c...Tertiary low voltage line terminal 0...Neutral point terminal (7317) Agent: Patent attorney Noriyuki Chika (
1 other person) Figure 1

Claims (2)

[Claims] (1) One tank houses the three-phase series winding and shunt windings wound around the core and its core legs, and the other tank houses the three-phase series winding and shunt windings wound around the core and its core legs. A tertiary low voltage winding, a tap winding and an excitation winding for each phase are housed, the series winding and the shunt winding are connected in series at the end of the medium voltage line, and the tap winding is connected to the shunt winding. A three-phase autotransformer characterized in that a shunt winding is connected in series between the neutral point side terminal and the neutral point, and the excitation winding is connected between the medium voltage line end and the neutral point. . (2) The tank that stores the series windings and shunt windings is divided into three parts, and each tank stores the iron core for each phase and the series windings and shunt windings wound around the core legs. Claim 1, characterized in that it is a combination of a tertiary low-voltage winding for three phases, a tap winding, and an excitation winding.
Three-phase autotransformer 1 described in Section 1