Arc modeling method for high-resistance ground fault of power transmission line

Abstract

The invention provides an arc modeling method for the high-resistance ground fault of a power transmission line. According to the method, a saturation current definite value IS and a reference voltage definite value UT are set according to the voltage level of a line, and the current iF of an arc branch is acquired. The arc voltage ua is calculated according to the formula ua=sgn(iF)*UT |n(|iF| / IS+1). After that, the fault point voltage is together established by the arc voltage in serial connection with a fixed grounding resistor RF. The above method is provided based on the Thompson principle for describing the air discharge essence, and the arc current is expressed based on the directional motion of a large number of electrons. Meanwhile, the function relationship between the arc voltage and the current is established based on the coupling relationship between the electric field and the electron avalanche motion in the arc space. In this way, a high-resistance ground fault arc model is established. According to the technical scheme of the invention, the physical nature of the air discharge of the arc fault is fully exploited. Therefore, the defect that a conventional arc differential equation is complex in computation and hard to directly apply can be overcome. The method is simple in computation and high in modeling accuracy, thereby having an important practical value in the field of subsequent high-resistance ground fault protection, control and ranging techniques.

Description

technical field [0001] The invention belongs to the technical field of power system protection and control, in particular to a modeling method for a high-resistance grounding fault arc of a transmission line. Background technique [0002] Affected by factors such as insulator flashover, lightning strikes, and mountain fires, high-voltage transmission lines often cause single-phase high-resistance grounding faults caused by discharges to surrounding tree branches, moso bamboo, and flame discharges through mountains. In recent years, there have been reports of high-resistance ground faults in most provinces of our country. High-resistance ground faults can easily lead to delays in differential protection, zero-sequence protection, and distance protection actions or even refusal to operate; the accuracy of the traditional ranging principle based on the impedance principle Remarkably decreased; due to the limitation of the starting threshold, the fault location and protection ac...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the shortcomings of traditional arc differential equations, which are complex in calculation and difficult to be directly applied to fault detection, and propose a high-impedance ground fault arc modeling method for transmission lines. The method is based on Thomson's principle describing the essence of air discharge. Use the directional movement of a large number of electrons to express the arc current, and then use the coupling relationship between the electric field and the electron avalanche movement in the arc space to establish the functional relationship between the arc voltage and current, thereby establishing a high-resistance ground fault arc model

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