JPH0374814A - Incombustible transformer - Google Patents

Abstract

PURPOSE:To reduce transportation size while gas seal is made sure, by cooling a transformer with incombustible liquid, colling a load time voltage regulator with insulating gas like SF6, making the gas pressure of the regulator lower than that of the transformer, and cutting off the pressure difference with a diaphragm. CONSTITUTION:On the main transformer side, an iron core 1a and a winding 2a wound around it are installed in a cooling liquid section 4 filled with cooling liquid 3. High pressure insulating gas 6a like SF4 gas is enclosed in a tank 5a. The liquid 3 and the gas 6a are isolated with a liquid section 4 wall. The liquid 3 whose temperature is raised by the heat generation of the coil 2a and the iron core 1a is circulated by using a pump 7a, and sent to a liquid cooler 12 through a cooling pipe 8a. On the regulator side, an iron core 1b and a winding 2b wound around it are accommodated in a tank 5b in which insulating gas 6b of a pressure lower than the main transformer is enclosed. In this part, similarly, the gas 6b whose temperature is raised is sent to a cooler 13 through a gas pipe 8b, and compulsorily circulated by a gas blower 7b.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to C, F, O (perfluorocarbon), for example.
The core and windings are cooled with non-flammable liquid such as SF,
This applies to non-flammable transformers that are insulated with an insulating gas such as (sulfur hexafluoride) gas, and particularly relates to non-flammable transformers that are transported separately into a main transformer and a load voltage regulator. .

(Conventional technology) With the increase in social safety awareness, insulating oil has traditionally been used for cooling and cooling.
There is an increasing demand for non-flammable transformers, compared to flammable oil-filled transformers that were previously insulated. Small and medium capacity non-flammable transformers include SF and gas-insulated transformers that are cooled and insulated with gas, but non-flammable transformers with a capacity exceeding 100MVA use C, F, , O for cooling. A non-flammable liquid such as In this case, the nonflammable liquid has a high specific gravity and is expensive, so it is used only for cooling the main heat generating parts such as the iron core and windings, and an insulating gas such as SFG gas is sealed in the tank, separated from the liquid part. It is common that science fiction
The sealing pressure of G gas is, for example, 3 to 3, which is the same as that of gas insulated switchgear.
Enclosed at 4 kg/cJ-g to increase dielectric strength.

In the case of C, F, and 0, the boiling point is approximately 100°C at atmospheric pressure, so if the coolant is used at atmospheric pressure, the liquid will vaporize in the high-temperature parts of the transformer's heat generating parts, and the dielectric strength will greatly decrease. descend. To prevent this, it is necessary to raise the pressure of the coolant compartment to the same level as the insulating gas and raise its boiling point.

Large-capacity non-flammable transformers are often installed in underground substations in cities with high demand for electricity. In this case, transportation and delivery conditions are difficult, so it is common to transport the transformer in parts. The unit of division is one unit for each phase and one load tap changer (hereinafter referred to as LTC) in the case of a three-phase converter, or one unit for each phase and one unit for load voltage regulator (hereinafter referred to as LVR). It is common to have a four-unit configuration consisting of: In the former case, it is necessary to electrically connect the tap leads drawn out from the tap windings in each phase tank to the LTC through a connection duct. In this case, if the number of tap points is 21, it is necessary to connect 14 leads for each phase to the LTC, so a large opening is required in the tank, but since the tank is filled with high-pressure gas, it is classified as a type 2 pressure It is a container, and it is difficult to provide a large opening due to its strength. Furthermore, since several external leads are passed through, the size of the connecting duct becomes large, making it difficult to place it in a limited space such as an underground substation.

Therefore, there is no need to pass the tap lead into the connection duct.
The VR system is the most suitable configuration for a split transport type non-flammable transformer.

(Problem to be solved by the invention) An LVR consists of a tap winding connected in series with the neutral point of the high voltage winding of the main transformer and an excitation winding connected in parallel with the medium voltage or low voltage winding of the main transformer. The wire is wound around the iron core and stored in the tank together with the LTC connected to the tap winding.
The phase transformer LVR is a three-phase transformer.

LVR requires a large opening for people to inspect the LTC and space for connecting the tap coil and LTC inside, so if it is used as a high-pressure gas pressure class 2 pressure vessel, it will be a 3-phase vessel and will be long. However, the weight and dimensions of the tank may increase and exceed transport and import restrictions. Also, as a seal for the LTC drive shaft, it can withstand differential pressure between the high gas pressure part and the outside.
Because there is no rotary seal that can be used over a long period of time and is highly reliable, it is necessary to keep the gas filling pressure in the LVR lower than that in the main transformer.

On the other hand, when the gas pressure of the LVR is lowered, the boiling point of the cooling medium kept at the same pressure as the gas pressure is lowered, causing the problem of lower dielectric strength as described above.

Furthermore, in liquid cooling, there are many sealing points at the portion where the tap lead is drawn out from the tap coil into the gas in the cooling liquid compartment, and there is also the problem that insulation and structural reliability are reduced.

It is an object of the present invention to provide a non-flammable transformer that is small in transportation size, has reliable gas sealing, has high reliability in insulation and cooling, and is low in cost.

[Structure of the invention]

(Means for Solving the Problem) The non-flammable transformer of the present invention cools the main transformer with a non-flammable liquid and cools the LVR with an insulating gas such as SF6, thereby controlling the gas pressure of the LVR as the main transformer. A gas partition plate is installed in the connection duct, which is lower than the gas pressure of the transformer and filled with gas through the connection lead that connects the LVR and the main transformer, to separate the gas pressure difference between the LVR and the main transformer. It is characterized by:

(Function) In the present invention, since no liquid is used in the LVR, there is no possibility that the liquid will leak from the cooling liquid compartment to the insulating gas side and the insulation will deteriorate. Dielectric strength does not decrease even if air bubbles are generated in the liquid.

Furthermore, since there is no need to use the LVR as a second-class pressure vessel, the transportation size and weight are reduced.

(Example) The present invention will be described below with reference to an example shown in the drawings. On the main transformer side, the iron core 1a and the winding 2 wound around the iron core 1a
a is installed in a coolant compartment 4 filled with a coolant liquid 3. An insulating gas 6a such as high-pressure SF or gas is sealed in the tank 5a, and the cooling liquid 3 and the insulating gas 6a are separated by a liquid compartment 4 wall.

The cooling liquid 3 whose temperature has increased due to the heat generated by the coil 2a and the iron core 1a is circulated by a pump 7a, sent to a liquid cooler 12 through a cooling pipe 8a, and cooled by air or water.

On the LVR side, there is an iron core 1b and a winding 2b wound around the iron core 1b.
is arranged in the tank 5b, and an insulating gas 6b having a lower gas pressure than the main transformer is sealed in the tank 5b.

The insulating gas 6b whose temperature has increased due to the heat generated by the coil 2b and the iron core 2a flows through the gas pipe 8b, is sent to the gas cooler 13, and is cooled by air or water. Insulating gas 6
b is forcedly circulated by the gas blower 7b or circulated by natural convection.

The main transformer consists of three single-phase transformers.

The windings of the main transformer and the LVR are electrically connected to each other, and the connection lead wire 9 is disposed within the connection duct 10. Since the main transformer, LVR, and insulating gas have different pressures, a gas partition plate 11 is installed in the middle of the connecting duct 10. A connecting lead wire 9 passes through this gas partition plate 11, but the structure is such that gas pressure differences can be sealed.

In order to insulate and cool the LVR using only gas, the tank 5b
The pressure of the gas sealed inside can be lowered than when using liquid cooling. Therefore, the tank 5b does not need to be a second class pressure vessel and can be made into a square shape similar to an oil-immersed transformer, which is advantageous for transportation. Also, since the differential pressure between the inside and outside of the tank becomes smaller, L
The rotational sealing performance of the portion where the TC drive shaft penetrates the tank is also improved.

Furthermore, there is no need for expensive non-flammable liquid or liquid compartment structure
VR can be produced at low cost.

Although the figure shows an example in which the core and windings of the main transformer are immersed in cooling liquid, the present invention is also applicable to so-called separate type gas insulated transformers that are cooled by attaching cooling panels to the windings and core. be done.

〔Effect of the invention〕

As described above, according to the present invention, by cooling the main transformer with a nonflammable liquid and cooling the LVR with an insulating gas such as SF, the gas pressure of the LVR can be made lower than the gas pressure of the main transformer. However, we installed a gas partition plate to separate the gas pressure difference between the LVR and the main transformer in the connection duct that is filled with gas through the connection lead that connects the LVR and the main transformer, so the transportation size is small and the gas Reliable sealing and insulation.

A non-flammable transformer with high cooling reliability and low cost can be obtained.

[Brief explanation of drawings]

The figure is a schematic configuration diagram showing one embodiment of the present invention. la...main transformer core 2a...Main transformer winding 3...Cooling liquid 5a...Main transformer tank 6...Insulating gas 7b...Gas blower 1b...LVR iron core 2b...LVR winding 4...Cooling fluid compartment 5b...LVR tank 7a...liquid pump 8a...Cooling pipe 8b...Gas piping 10...Connection duct 12...Liquid cooler 9... Connection lead wire 11...Gas partition plate 13...Gas cooler

Claims (1)

[Scope of Claims] An iron core, a winding wound around the core leg, a non-flammable cooling liquid that cools the core and the winding, a cooling liquid compartment that circulates the cooling liquid, and a cooling liquid compartment that is separated from the cooling liquid compartment. A tank containing an insulating gas, a cooling pipe connected to the cooling liquid section through the tank and circulating the cooling medium, and a liquid cooler connected to the cooling pipe and cooling the cooling medium. A main transformer, an iron core in a tank separate from the main transformer, an excitation winding and a tap winding wound around the iron core, an on-load tap changer electrically connected to the tap winding, and insulation. the main transformer and the main transformer; A non-flammable transformer characterized in that the on-load voltage regulator is electrically connected to the on-load voltage regulator through a connecting duct.