Thermal stability principle-based intermittent grounding protection method for small-resistance grounding system

Abstract

The invention provides a thermal stability principle-based intermittent grounding protection method for a small-resistance grounding system and aims to solve the problem that the single arcing duration of an intermittent grounding fault is often smaller than a protection action time limit, and the problem that traditional grounding fault protection is difficult to process, and other problems,so as to effectively remove intermittent grounding faults. According to the technical schemes, zero-sequence current is used for constructing heating characteristic values of all outgoing lines in a fault arcing period, heat difference is used for constructing heat dissipation characteristic values after arc extinguishing, protection action is conducted after the heating characteristic values exceed the limit, and intermittent grounding faults are removed. The method provided by the invention can be used as backup protection for outgoing line protection of the existing small-resistance grounding system, and improve the operation and power supply reliability of the system.

Description

technical field [0001] The invention relates to the field of grounding fault protection of distribution networks, in particular to an intermittent grounding protection method for a small resistance grounding system. Background technique [0002] The neutral point grounding method through a small resistance has the advantages of quickly removing permanent low-resistance grounding faults, effectively weakening resonance overvoltage, and relatively simple operation and maintenance. It is one of the commonly used neutral point grounding methods for large and medium-sized urban distribution networks. After a single-phase ground fault occurs in a small-resistance grounding system, it may be affected by factors such as arcing and extinguishing characteristics of the arc period, complex external effects such as wind force and air ionization, fault line galloping, and change in dielectric strength recovery performance. Alternate arcing, Intermittent grounding phenomenon of arc exting...

AI Technical Summary

Problems solved by technology

For intermittent ground faults, since the duration of single arcing, fault arcing-reignition interval and other conditions are unknown, it is difficult to fully adapt to complex and changeable faults by the method of "the number of faults exceeding the limit within a fixed period of time". Happening

Due to the complex environment of the medium-voltage distribution network and the high incidence of high-resistance grounding faults, when intermittent grounding is superimposed with high-resistance grounding problems, the problem of fault handling will be more complicated

Therefore, the problem of reliable protection against intermittent ground faults in small resistance grounding systems that takes into account the large-scale variation of transition resistance still needs to be further solved.

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