A Single-Phase Ground Fault Protection Method for Small Resistance Grounding System

Abstract

The invention provides a single-phase grounding fault protection method for a small resistance grounding system, which utilizes the time differential and the setting value to cooperate to realize the multi-level cooperation between the outlet circuit breaker, branch switch, boundary switch and distribution transformer protection, and selectively cut off Fault line: For high-resistance grounding faults, use the fault current traveling wave signal detected at the head end of each outgoing line of the substation to select the fault line, and exclude other causes of large unbalanced currents, and reduce the grounding protection setting. The sensitivity is greatly improved to ensure that the ground protection can still operate reliably in the event of a high-impedance ground fault. After a ground fault occurs, it can quickly and selectively remove the fault, and it is still effective when the transition resistance is as high as 1500Ω. It has an obvious effect on reducing the power outage range and power outage time of the distribution network fault.

Description

technical field [0001] The invention relates to the field of distribution network fault processing, in particular to a single-phase ground fault protection method for a small resistance grounding system. Background technique [0002] The neutral point adopts a small resistance grounding method to limit the overvoltage level of the non-faulted phase after a single-phase ground fault, overcome the ferromagnetic resonance of the ungrounded system and the series resonance overvoltage of the grounded system through the arc suppression coil, and the relay protection configuration is simple. In my country, with the development of the economy, in the densely populated central urban area, the distribution network structure is perfect to ensure the reliability of the power supply. faulty line. Based on this, the urban distribution networks in Shanghai, Beijing, Guangzhou, Shenzhen, Suzhou and other places in China have successively changed the grounding mode of non-grounding or arc-su...

AI Technical Summary

Problems solved by technology

[0004] At present, for feeder single-phase ground faults, the staged zero-sequence current protection scheme is mainly adopted, considering the influence of avoiding the downstream capacitive current of the protected line and the maximum unbalanced current during normal operation, the setting value of the zero-sequence current protection is too high, which can withstand The value of the transition resistance is generally only about 100Ω; and the ground fault in the actual distribution network is usually accompanied by tree barriers, incomplete breakdown of lightning arresters, and wires falling on the ground, ponds, etc., resulting in small current to ground and zero sequence overshoot. Flow protection often refuses to move

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