Low resistance grounding system inverse time lag zero sequence overcurrent grounding protection method based on transverse cooperation of each outlet line protection

Abstract

A low resistance grounding system high sensitivity inverse time lag zero sequence overcurrent grounding protection method belongs to the power distribution network relay protection field; for a low resistance grounding mode power distribution network, when single-phase earth fault happens, no matter how big a transition resistance is, the fault line zero sequence current is far greater than a health line zero sequence current, so an inverse time lag protection concept can be utilized to realize the cooperation between the fault line and the health line and grounding transformer protection; theinvention provides a setting method that uses the inverse time lag current protection for low resistance grounding system grounding fault protection, and a segment of specified time protection is added so as to improve the speediness of the high resistance grounding protection. The method can ensure the low resistance grounding and metal grounding fault protection to have excellent selectivity and reliability, and can solve the low resistance grounding system high resistance earth fault protection reliability problem, thus providing a wide real application prospect.

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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