Grounding protection method for small resistance grounding system based on zero-sequence current projection coefficient

Abstract

The invention provides a low-resistance grounding system ground protection method based on a zero sequence current projection coefficient and belongs to the field of power distribution network relay protection. For a low-resistance grounding mode power distribution network, projection coefficients of fault line zero sequence current and sound line zero sequence current on neutral-point zero sequence current have great difference no matter how much transition resistance is when a single-phase earth fault happens; thus, the fault characteristics can be utilized to form grounding protection. Theinvention further discloses a calculating method of the zero sequence projection coefficients and a fixed value setting principle of all parameters. The low-resistance grounding system ground protection method disclosed by the invention can ensure that low-resistance grounding and metallic grounding fault protection has good selectivity and reliability; meanwhile, the problem of high-resistance grounding fault protection reliability of a low-resistance grounding system is solved; the low-resistance grounding system ground protection method has a wide actual application prospect.

Description

technical field [0001] The invention relates to the field of relay protection for distribution networks, in particular to a grounding protection method for small resistance grounding systems based on zero-sequence current projection coefficients. Background technique [0002] With the advancement of urbanization, the application scale of power cables in power distribution networks is expanding day by day, and the capacitive current of the system is also gradually increasing. Compared with the resonant grounding system, the small-resistance grounding method has advantages in overvoltage suppression. In addition, the characteristic quantity of the ground fault is outstanding, and it is easy to realize relay protection coordination. In recent years, it has been gradually promoted and implemented in the new construction and renovation projects of urban distribution networks. However, unlike the small current grounding system, the small resistance grounding system requires immedi...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the protection problem when the grounding fault occurs in the feeder line in the small resistance grounding system.

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