A method of inverse-time zero-sequence overcurrent grounding protection for small-resistance grounding systems based on lateral coordination of each outlet protection

Abstract

The invention relates to an inverse-time zero-sequence overcurrent grounding protection method for a small resistance grounding system, which belongs to the field of distribution network relay protection. For the small resistance grounding distribution network, no matter how large the transition resistance is during a single-phase grounding fault, the zero-sequence current of the faulty line is far greater than the zero-sequence current of the healthy line. cooperation between protection. The invention provides a setting method for inverse time-limit current protection for grounding fault protection of a small resistance grounding system, and adds a section of definite time protection to improve the quick action of the protection for high-resistance grounding. The invention not only ensures good selectivity and reliability of the protection for low-resistance grounding and metallic grounding faults, but also solves the reliability problem of high-resistance grounding fault protection for small-resistance grounding systems, and has broad practical application prospects.

Description

technical field [0001] The invention relates to a grounding fault protection method for a small-resistance grounding system, which is suitable for a power distribution system in a small-resistance grounding mode and belongs to the field of relay protection for distribution networks. Background technique [0002] Since the medium-voltage distribution network is directly oriented to users, and single-phase ground faults account for about 80% of the total distribution network faults, reliable protection of single-phase ground faults has a significant impact on power supply reliability. The small resistance grounding system has the advantages of quickly cutting off the grounding fault, low overvoltage level, eliminating resonance overvoltage, using cables and electrical equipment with low insulation level, automatic fault removal, and convenient operation and maintenance. It is a more commonly used neutral One of the point grounding methods. However, unlike the small current gr...

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Problems solved by technology

[0006] The purpose of the present invention is to solve the protection problem when a high-resistance ground fault occurs in a low-resistance grounding system on the basis of ensuring the reliability and selectivity of low-resistance grounding and metallic grounding fault protection, and proposes a protection method based on each outgoing line. Coordinated small resistance grounding system with high sensitivity inverse time zero sequence overcurrent grounding protection method

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