CN107727989A - The test method of oil-gas casing structure transformer - Google Patents

Abstract

The invention provides a kind of test method of oil-gas casing structure transformer, comprise the following steps：Step S100, the isolation switch (600) in GIS seal assemblies (700) is disconnected, the second conductive connecting plate (400) for being electrically connected at grounding switch (300) exposed junction (B points) and being grounded between (500) of dismantling；Step S200, the test wire of test device is electrically connected to the exposed junction (B points) of the grounding switch (300)；Step S300, operate the grounding switch (300)；Step S400, transformer test project is performed by the test device.In accordance with the invention it is possible to by using isolation switch and grounding switch in metal enclosed switchgear, on the premise of without removing condenser type oil/SF6 set inner conductive tube connecting plates, every pilot project of transformer is completed.The workload of experiment work is substantially reduced, also ensure that SF₆The stable operation of air chamber.

Description

Test method for oil and gas bushing structure transformers

technical field

The invention relates to the field of transformer detection, in particular to a test method for an oil-gas bushing structure transformer.

Background technique

Gas insulated fully enclosed combined electrical appliances (English full name is gas insulated substation, referred to as GIS), GIS is a metal-enclosed switchgear that uses gas in whole or in part instead of air under atmospheric pressure as the insulating medium; it is composed of circuit breakers, busbars, A high-voltage power distribution device composed of high-voltage electrical appliances such as isolating switches, voltage transformers, current transformers, lightning arresters, bushings, connectors, and outlet terminals. Filled with a certain pressure of sulfur hexafluoride (SF ₆ ) gas with excellent insulation performance and arc extinguishing performance as the insulation and arc extinguishing medium, it is also called SF ₆ fully enclosed combined electrical appliance.

Compared with traditional open power distribution devices, GIS has compact structure, small footprint, flexible configuration, all components are sealed from environmental interference, strong environmental adaptability, strong safety, high operational reliability, convenient operation, and short maintenance intervals. Long, the maintenance interval of its main components is not less than 20 years, the maintenance workload is small, the installation is fast, the operating cost is low, and there is no electromagnetic interference.

In China's new large-scale generating sets, the insulation medium of transformers mostly adopts oil-immersed type, and the insulation medium of outlet metal-enclosed switchgear mostly adopts SF ₆ type. SF ₆ casing, that is, a gas-insulated fully enclosed combined electrical appliance (GIS). In the routine annual preventive test, the routine preventive test can only be carried out by displacing the SF ₆ gas in the metal-enclosed switchgear, dismantling the operating hand hole, and opening the outlet connector. After the test, it is necessary to clean the internal air chamber of the switch; reconnect the conductive connecting plate; refill SF ₆ gas and go through various maintenance items that are kept under pressure to ensure that the insulating gas does not leak out before the transformer can be put into operation again. In the process of replacing SF ₆ gas, it is easy to cause leakage of SF ₆ gas due to the process and the technical ability of the operator, (dry SF ₆ gas is very stable, and generally does not decompose by itself when the temperature is lower than 500 ° C, but in the presence of moisture When there is a large amount, it will be hydrolyzed when it leaks into the atmosphere: 2SF ₆ +6H ₂ O→2SO ₂ +12HF+O ₂ , and the HF in the product is highly corrosive and highly toxic to biological bodies. matter, SO ₂ generates sulfurous acid when it meets water, and can be further oxidized to generate sulfuric acid, which is also corrosive.) Causes irreversible harm to the atmospheric environment. In addition, during the reassembly process, due to the technical and material quality problems of the maintenance personnel, the sealing is not tight or the micro water exceeds the standard, which will cause delays in the rework of the equipment.

Contents of the invention

For this reason, the main purpose of the present invention is to provide a test method for transformers with oil-gas bushing structure, so as to achieve the following objectives: to minimize the disassembly and assembly work of the tested equipment in the test, without affecting the accuracy of the test results , greatly improving the safety factor of the equipment and saving the maintenance cost and maintenance period.

To achieve the above object, the present invention provides the following technical solutions:

A test method for a transformer with an oil-gas bushing structure, which includes the following steps: step S100, disconnecting the isolation knife switch in the GIS sealing assembly, and removing the second conductive connection electrically connected between the exposed end of the grounding knife switch and the ground. board; Step S200, electrically connect the test wire of the testing device to the exposed end of the grounding switch; Step S300, operate the grounding switch; Step S400, execute the transformer test item through the testing device.

Preferably, in the test method for transformers with oil and gas bushing structures, in step S300, close the grounding knife switch.

Preferably, the test method for transformers with oil-gas bushing structure, wherein the test item is a transformer DC resistance test.

Preferably, in the test method for transformers with oil and gas bushing structures, in step S300, disconnect the grounding knife switch.

Preferably, the test method for transformers with oil-gas bushing structure, wherein the test items are transformer insulation resistance, absorption ratio and polarization index tests.

Preferably, the test method for transformers with oil-gas bushing structure, wherein the test item is the transformer dielectric loss angle tgδ test.

Preferably, the test method for transformers with oil-gas bushing structure, wherein the test items are DC withstand voltage and leakage current tests of transformers.

According to the test method of the transformer with oil-gas bushing structure of the present invention, it can be completed without dismantling the conductive connecting plate in the capacitive oil/SF ₆ bushing by using the isolation switch and the grounding switch in the metal-enclosed switchgear. Transformer test items. The workload of the test work is greatly reduced, and the stable operation of the SF ₆ gas chamber is also guaranteed. It solves the equipment problems such as poor sealing, damp, and aging caused by the damage of the air chamber of the GIS sealing component. The work efficiency is improved, the stability of the equipment is guaranteed, and the measurement data is more accurate.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic diagram of the composition of a GIS according to an exemplary embodiment of the present invention;

2 is a flowchart of a test method for an oil-gas bushing structure transformer according to an exemplary embodiment of the present invention;

Fig. 3 is a schematic wiring diagram of a test method for an oil-gas bushing structure transformer according to Exemplary Embodiment 1 of the present invention;

Fig. 4 is a schematic wiring diagram of a test method for an oil-gas bushing structure transformer according to an exemplary embodiment 2 of the inventive concept.

[Description of Reference Signs]

100: Transformer 110: Oil and gas bushing (transformer high voltage transmission

out)

200: First conductive connecting plate 300: Grounding knife switch

400: Second conductive connecting plate 500: Ground

600: Isolation knife switch 700: GIS sealing assembly

710: Operating hand hole 900: Test device

detailed description

Regarding the detailed content and technical description of the present invention, examples are used for further description, but it should be understood that these examples are only for illustration, and should not be construed as limitations on the implementation of the present invention.

The new test method will be further described in detail below in conjunction with the accompanying drawings through specific embodiments.

FIG. 1 is a schematic configuration diagram of a GIS according to an exemplary embodiment of the present inventive concept.

1, the transformer 100 is connected to the GIS through the oil and gas bushing 110, and the GIS includes: a GIS sealing assembly 700; a first conductive connecting plate 200, a grounding knife switch 300 and an isolation knife switch 600 arranged in the GIS sealing assembly 700; The second conductive connecting plate 400 electrically connected to the exposed end (point B) of the grounding knife switch 300 and the grounding 500 electrically connected to the second conductive connecting plate 400 are provided on the outside of the GIS sealing assembly 700 .

Wherein, the GIS sealing assembly 700 is provided with an operating hand hole 710. When the GIS is working normally, the operating hand hole 710 is in a closed state, and the GIS sealing assembly 700 is filled with SF ₆ gas.

When carrying out various routine test items of the transformer with the traditional method, it is necessary to replace the SF ₆ gas in the GIS sealing assembly 700 before starting the test, open the operating hand hole 710, remove the first conductive connecting plate 200, and place the test device 900 The test can only be completed by electrically connecting the test line to the outlet (point A) of the high voltage output end of the transformer 100 .

After the test is completed, it is necessary to reconnect the first conductive connecting plate 200, close the operating hand hole 710, and fill the GIS sealing assembly 700 with SF ₆ gas. The steps are cumbersome and risky.

Fig. 2 is a flow chart of a test method for an oil-gas bushing structure transformer according to an exemplary embodiment of the present invention concept; Fig. 3 is a schematic wiring diagram of a test method for an oil-gas bushing structure transformer according to an exemplary embodiment 1 of the present invention concept ; FIG. 4 is a schematic wiring diagram of a test method for an oil-gas bushing structure transformer according to an exemplary embodiment 2 of the present invention.

The test method of the oil-gas bushing structure transformer provided by the embodiment of the present invention keeps the operating hand hole 710 of the GIS sealing assembly 700 closed, keeps the airtightness of the GIS sealing assembly 700, and uses the second conductive connecting plate in the GIS during the test 400, isolation knife switch 600, and grounding knife switch 300 to complete various routine test items of the transformer.

Example 1

Referring to Fig. 2 and Fig. 3, the test method of the oil-gas bushing structure transformer provided by the embodiment of the present invention includes the following steps:

Step S100, disconnect the isolation switch 600 in the GIS sealing assembly 700, and remove the second conductive connecting plate 400 electrically connected between the exposed end (point B) of the ground switch 300 and the ground 500;

Step S200, connecting the test line of the testing device 900 to the exposed end of the grounding switch 300 (point B);

Step S300, closing the grounding switch 300;

Step S400 , using the testing device 900 to perform a DC resistance test of a transformer.

Wherein, the DC resistance test of the transformer refers to measuring the DC resistance of the transformer winding together with the bushing. The DC resistance test of the transformer can be used to check the welding quality of the internal wire joints of the winding, the welding quality of the lead wire and the winding joint, whether the tap position of the voltage tap changer and the contact between the lead wire and the bushing are good, whether the parallel branch connection is correct, the transformer Whether there is a short circuit in the current-carrying part and whether there is a short circuit in the winding.

Example 2

Referring to Fig. 2 and Fig. 4, the test method of the oil-gas bushing structure transformer provided by the embodiment of the present invention includes the following steps:

Step S100, disconnect the isolation switch 600 in the GIS sealing assembly 700, and remove the second conductive connecting plate 400 electrically connected between the exposed end (point B) of the ground switch 300 and the ground 500;

Step S200, connecting the test line of the testing device 900 to the exposed end of the grounding switch 300 (point B);

Step S300, disconnecting the grounding switch 300;

Step S400 , using the test device 900 to perform transformer insulation resistance, absorption ratio and polarization index tests/dielectric loss angle tgδ tests/DC withstand voltage and leakage current tests.

Among them, the transformer insulation resistance test refers to: during the regular preventive test or after the occurrence of abnormal phenomena, the transformer is powered off to remotely measure its insulation resistance to check whether the insulation of the winding is damaged. When remote measuring the insulation resistance, first clean the porcelain sleeve, remove all the leads and the zero-phase bushing grounding wire, and use an insulated megohmmeter to test the high-voltage winding to ground (housing), the low-voltage winding to ground, and the gap between the high-voltage and low-voltage windings. insulation resistance value. When the measured insulation resistance is very small, the resistance reading R ₁₅ at the 15th second from the start of the test, the resistance reading R ₆₀ at the 60th second and the resistance reading R ₆₀₀ at the 600th second should be read respectively. Calculate the absorption ratio (absorption ratio = R ₆₀ /R ₁₅ ) and polarization index (polarization index = R ₆₀₀ /R ₆₀ ) in order to judge whether the insulation is damaged or the insulation is damp.

The transformer insulation dielectric loss test refers to: testing the loss of the insulating medium inside the insulating medium under the action of AC voltage, these losses include the loss caused by the polarization of the insulating medium, the loss caused by the surface discharge of the insulating medium and the internal discharge of the insulating medium Loss etc. Loss occurs inside the insulating medium, causing the power factor angle between the AC voltage and current applied to the insulating medium to no longer be 90°. The complementary angle of the power factor angle is called the dielectric loss angle, and tgδ is used to represent the dielectric loss characteristics of the insulation system capacitance. Use tgδ to represent the size of the relative dielectric loss factor, which has nothing to do with the geometric size of the insulating medium, which is convenient for comparing and judging the insulation performance of transformers with different structures.

Transformer DC withstand voltage and leakage current test refers to the measurement of leakage current of transformer coil winding, which is the same as the principle of measuring insulation resistance, but the sensitivity and accuracy of measuring transformer winding are higher than that of measuring insulation resistance. Therefore, defects such as cracks and surface carbonization of pure porcelain casings can be detected more effectively. When there is a defect inside the tested product, the leakage current will increase greatly with the increase of the voltage, and even a phenomenon of surge topping the surface will appear. The purpose is to detect whether the insulation properties of the transformer are up to standard.

Through this new test method, the maintenance steps of opening the operating hand hole 710 of the GIS sealing assembly 700 and removing the first conductive connecting plate 200 in the GIS sealing assembly 700 before the test can be eliminated, greatly reducing the number of tests on the equipment under test during the test. The disassembly and assembly work greatly improves the safety factor of the equipment and saves the maintenance cost and maintenance period without affecting the accuracy of the test results. In addition, because the internal contact resistance of GIS is small and fixed (about 50 microohms), the measurement data is more accurate.

The above content is only a preferred embodiment of the present invention, and cannot limit the implementation scope of the present invention, that is, any simple equivalent changes and modifications made according to the claims of the present invention and the contents of the description of the invention, All still belong to the scope that the present invention covers.

Claims (7)

1. a kind of test method of oil-gas casing structure transformer, it is characterised in that comprise the following steps：

Step S100, the isolation switch in GIS seal assemblies is disconnected, dismantle and be electrically connected at grounding switch exposed junction and ground connection Between the second conductive connecting plate；

Step S200, the test wire of test device is electrically connected to the exposed junction of the grounding switch；

Step S300, operate the grounding switch；

Step S400, transformer test project is performed by the test device.

2. the test method of oil-gas casing structure transformer according to claim 1, it is characterised in that

In step S300, the grounding switch is closed.

3. the test method of oil-gas casing structure transformer according to claim 2, it is characterised in that

The pilot project is DC Resistance Test of Transformer.

4. the test method of oil-gas casing structure transformer according to claim 1, it is characterised in that

In step S300, the grounding switch is disconnected.

5. the test method of oil-gas casing structure transformer according to claim 4, it is characterised in that

The pilot project is Insulation Resistance of Transformer, absorptance and polarization index experiment.

6. the test method of oil-gas casing structure transformer according to claim 4, it is characterised in that

The pilot project is tested for transformer dielectric loss angle tg δ.

7. the test method of oil-gas casing structure transformer according to claim 4, it is characterised in that

The pilot project is that transformer dc is pressure-resistant and leakage current test.