JPH0426308A - Small capacity distribution substation tower - Google Patents

Abstract

PURPOSE:To improve insulation performance by positioning a disconnecting means switching only an exciting current of a transformer, in a gas filled container together with a high voltage equipment on a small capacity distribution substation tower consisting of equipment at high voltage side and low voltage side. CONSTITUTION:A CT1 is positioned on an intermediate part of a conductor Li connected to high voltage lines A and B of two systems shown in a single line diagram, and a PT is connected between two-phase conductors. The primary winding(high voltage side) of a gas insulated transformer TR is connected to the conductor Li through a gas insulated circuit breaker DS/ES provided with an earth contactor. A CT2 and a low voltage distribution line Lo are connected to the secondary winding(low voltage side) of the transformer TR through a low voltage circuit breaker MCCB. All high voltage equipment from the input terminals of the high voltage lines A and B to the output terminals on the secondary side of the transformer TR is disposed collectively in one gas filled container GC.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a substation tower for small capacity power distribution.

[Prior art] A small-capacity power distribution substation tower is used as power receiving and transforming equipment, and consists of a high-voltage panel equipped with high-voltage side equipment including an instrument transformer, a switch, and a transformer, and a low-voltage panel equipped with low-voltage side equipment. It is used. In conventional small-capacity power distribution transformer towers, a high-voltage panel and a low-voltage panel are arranged in an aerial distribution panel. Therefore, for example, the conventional 6. 6kV.

For small capacity transformer towers of 150 kVA class or less, air load switchgears, oil-immersed transformers, molded transformers, molded instrument transformers, etc. are used. Furthermore, in conventional substation towers, fuses were connected in series to the instrument transformer and the transformer due to low insulation reliability.

[Problem to be solved by the invention] When a high voltage panel and a low voltage panel are arranged on an underground distribution panel like a conventional substation tower, the wiring between the high voltage side devices and a part of the high voltage side device body are exposed to the air. There is a problem in that the reliability of the insulation is lowered due to exposure to air, and there is also a problem in that it is susceptible to external influences such as humidity and dust. In addition, when high-pressure side equipment is placed in the atmosphere, maintenance and inspection of each equipment must be carried out regularly every year.Furthermore, when using fuses, maintenance such as replacing the fuses is required. There was a problem.

An object of the present invention is to provide a small-capacity power distribution transformer tower that has high insulation reliability and is maintenance-free.

[Means for Solving the Problems] The present invention provides a power distribution board that houses a high-voltage panel comprising high-voltage side equipment including at least an instrument transformer, a switch, and a transformer, and a low-voltage panel comprising low-voltage side equipment. The target is small-capacity power distribution substation towers. In the present invention, a new circuit switch that opens and closes only the excitation current of the transformer is used as the switch, and a gas insulated transformer that suppresses the amount of heat generated is used as the transformer.

The high-pressure side equipment is then housed in a gas container filled with insulating gas.

As the instrument transformer, at least one of an instrument transformer and a current transformer may be provided. The instrument transformer may be either a gas insulated instrument transformer or a molded instrument transformer.

Further, the disconnector may be provided with a grounding switch for grounding the power receiving side thereof as an attached structure.

[Function] Since a transformer with a small capacity and suppressed heat generation is used as a transformer, the heat generated by the transformer increases the temperature of the insulating gas to the extent that it adversely affects the operation of the switch (disconnector). Never. In addition, a disconnector is used as a switch, and the current that is switched (cut off) by the switch is only the excitation current of the transformer, so the amount of decomposed gas of the insulating gas generated when the disconnector operates is This can be suppressed to the extent that it does not adversely affect the insulator. Therefore, according to the present invention, it becomes possible to arrange high-pressure side equipment all at once in one gas container.

If high-voltage equipment is housed in a single gas container filled with insulating gas and gas-insulated as in the present invention, the main body of the high-voltage equipment and the wiring between each high-voltage equipment can be removed except for the power receiving terminal. It can be gas insulated, greatly improving insulation reliability. Furthermore, since the high-pressure side equipment is placed in a sealed gas container, the high-pressure side equipment is not affected by humidity or dust at all. Since the reliability of the insulation can be increased and it is not affected by external influences, there is no need to provide fuses for instrument transformers and transformers, which has the advantage of making the substation tower maintenance-free.

[Example code] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a single line diagram of a substation tower according to an embodiment of the present invention, in which a current transformer CTI is placed in the middle of a conductor connected to two lines A and B, and an instrument transformer PT is connected between the conductors of the two phases. The conductor Li is connected to a gas insulated transformer T via a gas insulated disconnector DS/ES equipped with an earthing switch.
A primary winding (high voltage side winding) of R is connected, and a low voltage circuit breaker MCCB is connected to a secondary winding (low voltage side winding) of transformer TR. A current transformer CT2 on the low voltage side is arranged on the power distribution line Lo. In this example, high voltage side equipment (CTI, FT
, DS/ES, TR) are housed in one common gas insulated gas container GC.

2(A) to 2(D) are schematic vertical cross-sectional views of an embodiment of a three-phase live circuit small-capacity distribution transformer tower constructed based on the connection diagram of FIG. 1; B-B line sectional view, C-C
They are a line sectional view and a DD line sectional view. In these figures, reference numeral 1 denotes a building-type power distribution board, and a gas container GC is arranged inside this power distribution board. The gas container GC is made of iron and has an airtight structure, and the bottom wall G of the gas container GC
A gas-insulated three-phase transformer TR is mounted on C1. This three-phase transformer TR is equipped with a voltageless tap changer TC, as schematically shown in FIG. 2(A), and a desired voltage can be obtained by this voltageless tap changer TC. . Note that if the usage conditions of the transformer tower are known in advance, a transformer TR with a predetermined transformation ratio may be prepared, and there is no need to provide a non-voltage tap changer TC. Note that the transformer TR is a small-capacity transformer of about 6.6 kV and 150 kVA, and one that generates as little heat as possible is used.

In order to suppress heat generation in a transformer, it is sufficient to reduce iron loss and copper loss, and for this purpose, iron cores and windings with as little loss as possible are used.

Above the transformer TR, there are three gas-insulated current transformers CT.
ll-CT13 is located. These current transformers are wound type current transformers, and their excitation conductors are conductors Lll to L1.
3 are connected to each other. The conductors LLl to L13 are
Terminal board 2 airtightly fixed to side wall GC2 of gas container GC
is electrically connected to two corresponding terminals of the terminal. On the terminal board 2, terminal rows consisting of three connection terminals are arranged in two rows, one above the other, and the upper terminal row has the cable conductor 3 of the A line.
is connected, and the lower terminal row has 8 cable conductors 3
is connected. An L-shaped connector 4 is attached to the tip of the cable conductor 3 rising from the bottom of the switchboard 1.
is attached, and the power receiving terminal portion exposed to the outside of the terminal board 2 is surrounded by L-shaped connectors 4 .

A gas-insulated potential transformer PT is connected between the excitation conductors of the current transformers CTII and CT12. The secondary outputs of these current transformers CT 11 to CT 13 and potential transformer PT are shown in FIGS. 2(B) and 2(C), which are drawn out to the outside of the gas container GC via a terminal board (not shown). As shown, on the top of the three current transformers CT11 to CT13,
A three-phase disconnector D S/ES is provided, which includes a grounding switch that grounds the power receiving side (cable 3 side). The disconnector DS/ES includes a rotating shaft 5 rotatably supported on both side walls of the gas container GC, and three contacts 6 fixed to the rotating shaft 5 in an insulated state. current transformer CTII
~ Three terminals 7 to which excitation conductors of CT 13 are connected...
・, one end is connected to the terminal 7... and the other end is always in contact with the corresponding contact 6... to connect the contact 6... to the terminal 7.
... three contact pieces 8 ... electrically connected to three contact pieces 8 ... and three contact pieces 8 ... connected to the primary winding of each single-phase transformer of three-phase transformer TR.
Consisting of three first contact terminals 9... and three second contact terminals 10 electrically connected to a ground terminal (not shown) provided on the wall of the gas container GC. . Figure 2 (
In the state shown in A), the contactor 6 of the disconnector DS/ES...
・It is not in contact with any of the contact terminals,
When supplying power, the contact 6... is the first contact terminal 9
When contacting... to disconnect and ground, contact 6
... comes into contact with the second contact terminal 10.... The disconnect switch is operated by a disconnect switch operator 11 installed outside the gas container GC.
This is done using When the rotating arm 12 of the disconnector operator 11 is rotated clockwise, the connecting arm 1 shown partially
3, a rotating arm (not shown) connected to the rotating shaft 5 rotates clockwise, and the contacts 6...
It is connected to the contact terminal 10 of.

As shown in FIGS. 2(A) and 2(D), the output terminal of the secondary winding of the three-phase transformer TR is connected to four bushings 14 airtightly fixed to the wall GC3 of the gas container GC. is connected to one end of the conductor. The other ends of the conductors of the bushing 14 (the ends outside the gas container) are respectively connected to corresponding input terminals of the low voltage circuit breaker MCCB. Low voltage circuit breaker MC
Low voltage side current transformers CT21 to CT23 are provided in the distribution lines Lo1 to Lo3 output from the CB.

Inside the steel gas container GC, there is a non-flammable and extremely stable S.
It is filled with F6 gas, making it extremely safe in terms of disaster prevention.

In the above embodiment, a transformer with a small capacity and suppressed heat generation is used as the three-phase transformer TR, so the temperature of the SF6 gas, which is an insulating gas, is
It does not rise to the extent that it adversely affects the operation of the disconnector DS/ES. In addition, since a disconnector DS/ES is used as a switch, and the current switched by the switch is only the excitation current of the transformer TR, the SF6 generated when the disconnector operates
By reducing the amount of decomposed gas, it is possible to prevent the insulators of the transformer from being adversely affected by this decomposed gas.

If the high-pressure side equipment is housed and arranged in one gas container GC as in the above embodiment, the protection device such as gas leak monitoring can be integrated into one system, and the configuration of the protection device can be simplified. . Furthermore, since the insulation performance is improved, there is no need to provide a protective fuse for the instrument transformer and the three-phase transformer, and the substation base can be made maintenance-free. Furthermore, since the terminal section on the power receiving side is covered with a removable cable terminal (L-shaped connector) that does not expose the live part, the structure is such that the live part on the high voltage side is not exposed at all, providing extremely high insulation and safety. can be increased.

In the above embodiment, a disconnector having a structure with an attached earthing switch was used, but it is not an essential requirement to include the function of an earthing switch.

Further, the instrument transformers (CT and PT) may be either gas insulated transformers or molded transformers made of epoxy molded products.

[Effects of the Invention] According to the present invention, a transformer with a small capacity and suppressed calorific value is used as a transformer, and only the excitation current of the transformer is cut off by a new circuit switch, so that one gas The high-voltage side equipment can be placed all together in the container, and as a result, the main body of the high-voltage side equipment and the wiring between each high-voltage side equipment, excluding the power receiving terminal, can be gas-insulated, improving the reliability of the insulation. can be significantly improved. In addition, because the high-voltage equipment is placed inside a sealed gas container, the high-voltage equipment is completely unaffected by humidity and dust, which increases insulation reliability. There is an advantage that the substation tower can be maintenance-free by eliminating the need to provide a fuse for the substation.

[Brief Description of the Drawings] Fig. 1 is a single line diagram of a substation tower according to an embodiment of the present invention.
FIG. 2(A) is a schematic vertical cross-sectional view of an embodiment of a three-phase finger-shaped small-capacity power distribution substation constructed based on the wiring diagram of FIG. 1;
Figure 2 (B) is a sectional view taken along the line B-B of Figure 2 (A), Figure 2 (C) is a sectional view taken along the line CC of Figure 2 (A), and Figure 2 (D).
is a sectional view taken along line DD in FIG. 2(A). CTI, CT11~CT13...Current transformer, PT...
Instrument transformer, TR...three-phase transformer, GC...gas container, DS/ES...disconnector with earthing switch, MC
CB...Low voltage circuit breaker, CT2. CT21~CT23・
...Low voltage side current transformer, 1...Switching board, 2...Terminal board,
3... Cable, 4... L-shaped connector, 11...
Disconnector operator, 14...Figure Figure Figure ([))

Claims (1)

[Scope of Claims] For small-capacity power distribution in which a high-voltage panel comprising high-voltage side equipment including at least an instrument transformer, a switch, and a transformer and a low-voltage panel comprising low-voltage side equipment are housed in a distribution board. In the substation tower, a disconnector that only opens and closes the excitation current of the transformer is used as the switch, a gas-insulated transformer with suppressed calorific value is used as the transformer, and the high-voltage side equipment is sealed with insulating gas. A small-capacity power distribution substation characterized by being housed in a single gas container.