Protection method suitable for low resistance grounding system single phase grounding fault

Abstract

A low resistance grounding system single phase grounding fault protection method belongs to the power distribution network relay protection field. A generation probability of a low resistance grounding system high resistance grounding fault is large. A zero sequence overcurrent protection method of a traditional fixed setting value is easy to generate unwanted operation. In the method, according to a relation among a fault point transition resistor, a zero sequence voltage and each outgoing line zero sequence current when a grounding fault is generated, the zero sequence voltage is taken as a brake amount so as to determine a zero sequence overcurrent protection setting value. If a zero sequence voltage amplitude is greater than a knee point voltage, the zero sequence overcurrent protection setting value is increased according to a certain proportion; otherwise, the zero sequence overcurrent protection setting value keeps the same and is a set value during normal operation. By using the method, adaptive adjustment of the zero sequence overcurrent protection setting value under the condition of the different transition resistors can be realized; and protection sensitivity to a small resistance grounding fault and a metallicity grounding fault and protection reliability to a high resistance grounding fault are considered.

Description

technical field [0001] The invention relates to a single-phase ground fault protection method for a small-resistance grounding system, which is suitable for a small-resistance grounding mode distribution network with zero-sequence overcurrent protection, and belongs to the field of distribution network relay protection. Background technique [0002] Affected by factors such as the natural environment and power transmission corridors, nonlinear high-resistance ground faults often occur in neutral-point effectively grounded distribution networks, and the short-circuit current is small. The traditional zero-sequence overcurrent protection with a fixed value cannot operate reliably to remove the fault. Due to the long-term existence of faults, fire accidents are prone to occur at fault points, and casualties will be caused in severe cases. In recent years, when a single-phase high-resistance ground fault occurs, how to correctly detect the fault and act as a trip or send an alar...

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Problems solved by technology

However, for the high-impedance grounding situation where the nonlinear characteristics are not obvious a

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