Method for simulating GIS transformer substation to produce very fast transient overvoltage (VFTO) and test circuit

Abstract

The invention provides a method for simulating a gas insulated switchgear (GIS) transformer substation to produce very fast transient overvoltage (VFTO) by a test circuit and the test circuit. The test circuit comprises a first isolating switch gear, a second isolating switch gear, a first isolating pipe sleeve, a second isolating pipe sleeve and a branch bus, wherein one end of the first isolating switch gear is connected with one end of the second isolating switch gear via a pipeline; and the other end of the first isolating switch gear is connected with one end of th first isolating pipe sleeve via a pipeline; the other end of the second isolating switch gear is connected with one end of the second isolating pipe sleeve; one end of the branch bus is connected with the pipeline between the first isolating switch gear and the first isolating pipe sleeve and the other end thereof is overhung; and VTTO waveforms occurring on isolating switch fractures and GIS pipelines in the GIS transformer substation are simulated by changing the length of the branch bus under different GIS connection modes.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a method and a test circuit for simulating the ultra-fast transient overvoltage generated in a gas-insulated metal-enclosed switchgear GIS substation through a test circuit. Background technique [0002] With the development of power technology, at present, the power industry standard GB1985-89 (AC high-voltage disconnector and grounding switch) clearly stipulates that the disconnector in the gas-insulated metal-enclosed switchgear (GIS, GasInsulated Switchgear) substation must be opened and closed. Capacitive current test method, and recommended test circuit, to test and assess the ability of the disconnector to close and break small capacitive current. [0003] Such as figure 1 As shown, it is a schematic diagram of the disconnector test wiring circuit in the prior art, in which figure 1 Among them, U1 represents the power supply voltage, and its AC voltage amplitude ...

AI Technical Summary

Problems solved by technology

The waveform of the VFTO generated under this condition is different from that of the VFTO occurring in the UHV GIS substation, and it is difficult to judge whether the maximum VFTO amplitude will occur in the project

The VFTO that appears in the UHV GIS substation is caused by the multiple refraction and reflection of the voltage wave at the discontinuous point of the wave impedance. The difference in the GIS wiring mode causes the position of the maximum amplitude of the VFTO to appear when the isolating switch is operated at different positions. Uncertainty

[0005] Therefore, the isolation switch in the GIS proposed by the current power industry standard must be opened and closed. The small capacitive current test circuit cannot truly reflect the VFTO waveform that appears in the UHV GIS substation, and the position where the maximum value of VFTO occurs is basically fixed. That is, on the fracture of the disconnected switch

[0006] During the research and practice of the prior art, the inventor of the present invention found that in the existing implementation, when the disconnector is operated in the GIS substation, the largest VFTO does not necessarily appear at the fracture of the disconnector. It may appear at a certain point on the busbar. For this situation, the test circuit proposed by the current power industry standard cannot fully simulate and measure the VFTO waveform appearing in the GIS substation, which has very large limitations.

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