Device for judging inductance and capacitance of loop of transformer test system

Abstract

The utility model belongs to the field of transformer test, and relates to a device for judging the inductance and capacitance of a transformer test system loop, a current transformer is arranged on a three-phase branch between the output end of a three-phase voltage regulator and a fling-cut switch I, and an acquisition card and a PLC (Programmable Logic Controller) control mechanism are electrically connected with a computer host; the acquisition card is electrically connected with a current transformer in a three-phase branch, the acquisition card is electrically connected with the three-phase branch at the output end of the three-phase voltage regulator through a voltage transformer, and the capacitor tower is electrically connected with the three-phase branch between the first fling-cut switch and the second fling-cut switch through a third fling-cut switch. The intermediate transformer is electrically connected with the three-phase branch between the first fling-cut switch and the second fling-cut switch through the fourth fling-cut switch, and the PLC control mechanism is electrically connected with the first fling-cut switch, the second fling-cut switch, the third fling-cut switch, the fourth fling-cut switch and the three-phase voltage regulator. A user can judge whether a transformer test loop has capacitive or inductive characteristics by using the test device before a transformer officially performs a temperature rise or load pressurization test.

Description

Technical Field

[0001] This utility model belongs to the field of transformer testing technology, specifically relating to a device for determining the inductive and capacitive properties of a transformer testing system circuit. Background Technology

[0002] With the rapid development of my country's economy and the gradual improvement of people's living standards, the requirements for the safety and reliability of power grid operation are becoming increasingly stringent. As a core piece of equipment in the power grid, the operating status of power transformers directly affects the stable operation of the grid.

[0003] Load and temperature rise tests are part of the factory testing of transformers. For large-capacity transformers, load and temperature rise tests require capacitor compensation, which necessitates comprehensive calculations based on applied voltage, applied current, and the turns ratio of the intermediate transformer. Excessive compensation capacitance can lead to overcompensation, causing generator self-excitation. Currently, there is no quick and easy testing device to determine the inductive and capacitive properties of a transformer test system circuit. Summary of the Invention

[0004] To solve the above-mentioned technical problems, this utility model provides a device for determining the inductive and capacitive properties of a transformer test system circuit. The technical solution adopted by this utility model is as follows:

[0005] A device for determining the inductive and capacitive properties of a transformer test system circuit includes a three-phase voltage regulator, a data acquisition card, a PLC control mechanism, and a computer host. The output terminals of the three-phase voltage regulator are electrically connected to the transformer test object via switching switches one and two, respectively. Current transformers are installed on the three-phase branches between the output terminals of the three-phase voltage regulator and switching switch one. The data acquisition card and the PLC control mechanism are electrically connected to the computer host. The data acquisition card is electrically connected to the current transformers in the three-phase branches, and the data acquisition card is also electrically connected to the three-phase branches of the output terminal of the three-phase voltage regulator via voltage transformers. A capacitor tower is electrically connected to the three-phase branches between switching switches one and two via switching switch three. The PLC control mechanism is electrically connected to switching switches one, two, three, and the three-phase voltage regulator.

[0006] Preferably, the intermediate transformer is electrically connected to the three-phase branch between switching switch one and switching switch two via switching switch four, and the PLC control mechanism is electrically connected to switching switch four.

[0007] Preferably, the input terminal of the three-phase voltage regulator is electrically connected to the AC power supply through a circuit breaker, and the PLC control mechanism is electrically connected to the circuit breaker.

[0008] The beneficial effects of this utility model are:

[0009] Users can use this device to determine whether the transformer test circuit exhibits capacitive or inductive characteristics before the formal temperature rise or load pressure test. When the test circuit is detected to exhibit capacitive characteristics, this device will issue an alarm signal and prohibit the test system from closing for testing. This can prevent the generator from self-excitation due to excessive compensation capacity of the capacitor tower during load and temperature rise tests. Attached Figure Description

[0010] 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:

[0011] Figure 1 This is a schematic diagram illustrating the structure and principle of the experimental device according to an embodiment of the present invention. Detailed Implementation

[0012] 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.

[0013] like Figure 1 As shown, a device for determining the inductive and capacitive properties of a transformer test system circuit includes a three-phase voltage regulator (TYQ), a data acquisition card, a PLC control mechanism, and a computer host. The input terminals of the three-phase voltage regulator are electrically connected to the three-phase outputs of an AC 380V power supply (a generator can be used) via circuit breakers (K1). The output terminals of the three-phase voltage regulator are electrically connected to the transformer under test via switching switches one (G1) and two (G2). Current transformers (CTs) are installed on the three-phase branches between the output terminals of the three-phase voltage regulator and switching switch one.

[0014] The data acquisition card and PLC control mechanism are electrically connected to the computer host, which is housed in a chassis. The data acquisition card is electrically connected to the current transformers in the three-phase branches. The three-phase branches between the output of the three-phase voltage regulator and the current transformers are electrically connected to the data acquisition card via voltage transformers (PTs). Preferably, the data acquisition card is an NI USB6001 model. The capacitor tower is electrically connected to the three-phase branches between switching switches one and two via switching switch three (G3). The intermediate transformer is electrically connected to the three-phase branches between switching switches one and two via switching switch four (G4). The PLC control mechanism is electrically connected to switching switches one, two, three, and four, and the three-phase voltage regulator (…). Figure 1 The wiring between the PLC control mechanism and switching switches two, three, and four is not shown in the diagram.

[0015] After the capacitor tower is assembled and put into operation, before formally conducting temperature rise or load tests, the overall load characteristics of the test circuit of the transformer under test should be detected using this test device first. (Note that when using this test device to detect the overall load characteristics of the test circuit, the intermediate transformer should not be connected to the test circuit first, i.e., the four switching switches should be in the open state.)

[0016] The three-phase voltage regulator in this test setup can output 0-400V as the test power supply for the test circuit. The voltage and current waveforms output by the three-phase voltage regulator are measured by a data acquisition card, and the data is processed by the computer host to determine the phase angle difference between the voltage and current, thereby determining whether the test circuit exhibits inductive or capacitive characteristics. When the computer host detects that the current phase leads the voltage phase, it indicates that the overall load of the circuit exhibits capacitive characteristics. At this time, the computer host will issue an alarm signal and provide connection control through the PLC control mechanism. The PLC control mechanism controls the circuit breaker and switching switch to disconnect, prohibiting the AC 380V power output from closing and the intermediate transformer from closing, to avoid the occurrence of capacitive loads during the test.

[0017] The device for determining the inductive and capacitive properties of a transformer test system circuit provided in this embodiment of the invention has the following specific working process:

[0018] ① Complete the wiring for the transformer test specimen load or temperature rise test; ② Complete the selection of the intermediate transformer turns ratio and perform capacitor compensation using the capacitor tower (close switch three); ③ Sequentially close switch one, switch two, and the circuit breaker; ④ Start the computer host, control the three-phase voltage regulator to boost the voltage through the PLC control mechanism, and collect voltage and current signals using the data acquisition card; ⑤ The computer host performs calculations to determine the phase relationship between voltage and current; ⑥ If the transformer test circuit is determined to be a capacitive load, disconnect the circuit breaker, readjust the capacitor tower for capacitor compensation, and then start the operation from step ③ until the transformer test circuit is an inductive load; if the test circuit is determined to be an inductive load, close switch four and connect the intermediate transformer for load or temperature rise test.

[0019] This invention innovates a technology to prevent overcompensation during transformer load and temperature rise tests. It establishes a test device for judging the inductive and capacitive properties of the transformer test system circuit, which can avoid overcompensation of the capacitor tower during transformer load and temperature rise tests, thus preventing generator self-excitation.

[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 device for determining the inductive and capacitive properties of a transformer test system circuit, comprising a three-phase voltage regulator, a data acquisition card, a PLC control mechanism, and a computer host, wherein the output terminals of the three-phase voltage regulator are electrically connected to the transformer test specimen via switching switches one and two, characterized in that, Current transformers are installed on the three-phase branches between the output terminal of the three-phase voltage regulator and the switching switch one. The data acquisition card and PLC control mechanism are electrically connected to the computer host. The data acquisition card is electrically connected to the current transformers in the three-phase branches. The data acquisition card is also electrically connected to the output terminal three-phase branches of the three-phase voltage regulator via voltage transformers. The capacitor tower is electrically connected to the three-phase branches between switching switches one and two via switching switch three. The PLC control mechanism is electrically connected to switching switches one, two, three and the three-phase voltage regulator.

2. The device for determining the inductive and capacitive properties of a transformer test system circuit according to claim 1, characterized in that, The intermediate transformer is electrically connected to the three-phase branch between switching switch one and switching switch two via switching switch four, and the PLC control mechanism is electrically connected to switching switch four.

3. The device for determining the inductive and capacitive properties of a transformer test system circuit according to claim 1, characterized in that, The input terminal of the three-phase voltage regulator is electrically connected to the AC power supply through a circuit breaker, and the PLC control mechanism is electrically connected to the circuit breaker.

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