Single-phase autotransformer partial discharge test system

Abstract

The utility model belongs to the field of transformer discharge test, and relates to a partial discharge test system for a single-phase autotransformer, which is characterized in that the three-phase output end of a test power supply is electrically connected with a first switch, and the first switch is connected with a second switch in series to form an A-phase branch, a B-phase branch and a C-phase branch; the three compensation reactors are electrically connected with the A-phase branch, the B-phase branch and the C-phase branch through the first compensation switches, the three compensation reactors are electrically connected with the C-phase branch through the second compensation switches, and the three second switches are electrically connected with the three-phase input end of the intermediate transformer. A three-phase output end of the intermediate transformer is electrically connected with low-voltage windings of the A-phase autotransformer, the B-phase autotransformer and the C-phase autotransformer, a standard current transformer is mounted on a three-phase input end line of the intermediate transformer, and a standard voltage transformer is mounted on a three-phase output end line of the intermediate transformer. The partial discharge test device is simple in structure and convenient to operate, and partial discharge tests can be carried out on three single-phase autotransformers at the same time.

Description

Technical Field

[0001] This utility model belongs to the field of transformer discharge testing technology, specifically relating to a partial discharge testing system for a single-phase autotransformer, which can simultaneously perform partial discharge tests on three single-phase autotransformers. Background Technology

[0002] With the rapid development of the national power industry, the demand for large-capacity, high-voltage transformers is increasing. However, these transformers are often manufactured as large-capacity single-phase autotransformers due to their excessive capacity and voltage level. In actual operation, three identical single-phase autotransformers are typically assembled into a YNaod11 structure. Therefore, customer orders usually consist of three single-phase autotransformers with identical parameters and structures. Based on their production cycles, transformer manufacturers need to conduct partial discharge tests on this type of large-capacity single-phase autotransformer. How to save production time while simultaneously ensuring the economic efficiency and rationality of partial discharge testing has become a pressing technical issue for transformer manufacturers.

[0003] According to power transformer technical standards, partial discharge testing is a routine factory test for power transformers. Currently, transformer manufacturers have a large number of orders and saturated production capacity. Improving production efficiency, strengthening contract fulfillment capabilities, and shortening production cycles have become urgent issues for transformer manufacturers. At the same time, economic efficiency must be considered, minimizing the partial discharge test time and reducing transformer production costs. Therefore, it is necessary for technical personnel to optimize the partial discharge test process for single-phase autotransformers. Summary of the Invention

[0004] This invention innovates the partial discharge test method for single-phase autotransformers based on the power transformer test standards. It employs a test power supply, a reactor group compensation device, and an intermediate transformer to conduct partial discharge tests on three large-capacity single-phase autotransformers with identical parameters. The technical solution adopted in this invention is as follows:

[0005] A partial discharge test system for a single-phase autotransformer includes a test power supply and compensating reactors. The single-phase autotransformer includes an A-phase autotransformer, a B-phase autotransformer, and a C-phase autotransformer. The three-phase output terminals of the test power supply are electrically connected to a first switch. The first switch is connected in series with a second switch to form an A-phase branch, a B-phase branch, and a C-phase branch. The three compensating reactors are electrically connected to the A-phase branch, the B-phase branch, and the C-phase branch through a first compensating switch. The three compensating reactors are electrically connected to the C-phase branch through a second compensating switch. The three second switches are electrically connected to the three-phase input terminals of an intermediate transformer. The three-phase output terminals of the intermediate transformer are electrically connected to the low-voltage windings of the A-phase, B-phase, and C-phase autotransformers. Standard current transformers are installed on the three-phase input terminals of the intermediate transformer, and standard voltage transformers are installed on the three-phase output terminals of the intermediate transformer.

[0006] Preferably, the test power supply is a generator set or a frequency converter.

[0007] The beneficial effects of this utility model are:

[0008] This invention has a simple structure and is easy to operate. It enables simultaneous partial discharge testing of three single-phase autotransformers, greatly shortening the partial discharge test time and reducing production costs, thus achieving cost reduction and efficiency improvement. Attached Figure Description

[0009] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0010] Figure 1 This is an architectural diagram of the partial discharge test system for a single-phase autotransformer according to an embodiment of this utility model;

[0011] Figure 2 This is a schematic diagram of three single-phase autotransformers connected in group YNa0d11;

[0012] In the diagram, 1 is the test power supply, 2 is the compensation reactor, 3 is the intermediate transformer, 4 is the three tested single-phase autotransformers, 5 is the first compensation switch, 6 is the first switch, 7 is the second switch, 8 is the standard current transformer, 9 is the standard voltage transformer, 10 is the A-phase autotransformer, 11 is the B-phase autotransformer, 12 is the C-phase autotransformer, 13 is the iron core, 14 is the clamp, and 15 is the second compensation switch. Detailed Implementation

[0013] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0014] A 500kV three-winding autotransformer typically consists of three single-phase autotransformers, which are procured and manufactured simultaneously. For a single-phase autotransformer winding, I represents the high-voltage winding, i represents the low-voltage winding, a represents the low-voltage winding in an autotransformed winding group, and 0 represents the electrical angle difference between the high and low voltage windings. The connection group for a single-phase autotransformer is Ia0i0, indicating the winding connection as follows: the high-voltage and low-voltage windings are autotransformed with a phase difference of 0; or the high-voltage and low-voltage windings are not autotransformed with a phase difference of 0. Three single-phase autotransformers connected together form a 500kV three-winding autotransformer, with a connection group of YNa0d11. Y represents a star connection on the high-voltage side, N represents a neutral point lead on the high-voltage side, a represents autotransformation, 0 represents no phase shift, YNa0 represents a star connection with no phase shift, and d represents a delta connection.

[0015] Similar to conventional three-phase, three-winding oil-immersed transformers, the 500kV three-winding autotransformer can be subjected to partial discharge tests using conventional testing methods. This invention connects three single-phase autotransformers in a YNa0d11 configuration to form a 500kV three-phase autotransformer. The testing method follows the conventional test scheme for three-phase, three-winding oil-immersed transformers. The three-phase output voltage of the test power supply is connected to a compensating reactor group, stepped up by an intermediate transformer, and then supplied at low voltage to the three single-phase autotransformers to achieve the purpose of simultaneously conducting partial discharge tests on the three single-phase autotransformers.

[0016] Theoretically, this invention involves three single-phase autotransformers designed and manufactured with identical parameters, meeting the requirements for parallel operation. They will subsequently operate in the same YNa0d11 connection group. Appropriate testing equipment can be selected based on the capacity and test parameters of the single-phase autotransformers to simultaneously conduct partial discharge tests on all three. This effectively reduces the partial discharge test time of two single-phase autotransformers, shortens the overall transformer production cycle, and reduces the start-up and shutdown losses of the test power supply 1, thus achieving cost reduction and efficiency improvement.

[0017] like Figure 1As shown, a partial discharge test system for a single-phase autotransformer includes a test power supply 1, which provides power for the partial discharge test. The test power supply 1 is a generator set or a frequency converter. The test power supply 1 is electrically connected to three first switches 6 to output three-phase voltage. The three first switches 6 are connected in series with three second switches 7 to form phase A, phase B, and phase C branches. Three compensating reactors 2 are electrically connected to phase A, phase B, and phase C branches respectively through first compensating switches 5, and to phase C branch respectively through second compensating switches 15. The compensating reactors 2 provide reactive power compensation during the partial discharge process, eliminating reactive power and suppressing harmonics in the test system. Each phase output from the test power supply 1 is electrically connected to one compensating reactor 2. Three second switches 7 are electrically connected to the three-phase input terminals of the intermediate transformer 3, and the three-phase output terminals of the intermediate transformer 3 are electrically connected to the low-voltage windings of three tested single-phase autotransformers 4. Standard current transformers 8 are installed on the three-phase input terminals of the intermediate transformer 3. Figure 1 In the CT), standard voltage transformers 9 are installed on the three-phase output lines of intermediate transformer 3 respectively. Figure 1 (PT in the middle). Intermediate transformer 3 is used to increase the voltage to provide the voltage required for the test. Each phase line is equipped with a standard current transformer 8 and a standard voltage transformer 9 to monitor the current and voltage in each phase line and ensure the safety of the line. First switch 6, second switch 7, first compensation switch 5 and second compensation switch 15 are the physical connection points of the line during the test, playing a role in safety protection.

[0018] This embodiment of the invention combines the original three single-phase autotransformers 4 under test into a single three-phase autotransformer for simultaneous three-phase partial discharge testing, significantly shortening the testing time. For example... Figure 2 As shown, the connection structure of the three tested single-phase autotransformers 4 is as follows:

[0019] The low-voltage windings a~y, b~z, and c~x of the A-phase autotransformer 10, B-phase autotransformer 11, and C-phase autotransformer 12 form a delta connection structure; abc are the start terminals of the low-voltage windings, and xyz are the corresponding tail terminals of the low-voltage windings. The neutral point Om of the A-phase autotransformer 10, B-phase autotransformer 11, and C-phase autotransformer 12 is short-circuited to ground; the core 13 and clamp 14 of the A-phase autotransformer 10, B-phase autotransformer 11, and C-phase autotransformer 12 are grounded respectively. A, B, and C represent the high-voltage three phases; Am, Bm, and Cm represent the medium-voltage three phases; and a, b, and c represent the low-voltage three phases.

[0020] In this embodiment of the utility model, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.

[0021] Finally, it should be noted that the above embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model.

Claims

1. A partial discharge test system for a single-phase autotransformer, comprising a test power supply and a compensating reactor, wherein the single-phase autotransformer includes an A-phase autotransformer, a B-phase autotransformer, and a C-phase autotransformer, characterized in that, The three-phase output terminals of the test power supply are electrically connected to the first switch. The first switch is connected in series with the second switch to form the A-phase branch, B-phase branch, and C-phase branch. The three compensating reactors are electrically connected to the A-phase branch, B-phase branch, and C-phase branch through the first compensating switch. The three compensating reactors are electrically connected to the C-phase branch through the second compensating switch. The three second switches are electrically connected to the three-phase input terminals of the intermediate transformer. The three-phase output terminals of the intermediate transformer are electrically connected to the low-voltage windings of the A-phase autotransformer, B-phase autotransformer, and C-phase autotransformer. Standard current transformers are installed on the three-phase input terminals of the intermediate transformer, and standard voltage transformers are installed on the three-phase output terminals of the intermediate transformer.

2. The partial discharge test system for a single-phase autotransformer according to claim 1, wherein The test power supply is a generator set or a frequency converter.

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