Grounding fault detecting method, system and storage medium based on steady state fault quantity

Abstract

The invention discloses a grounding fault detecting method based on a steady state fault quantity. The method comprises the following steps: collecting a three-phase voltage, a zero-sequence voltage and a zero-sequence current of a system to be detected; comparing whether the zero-sequence voltage is greater than a starting threshold value of the zero-sequence voltage, if so, judging that a single-phase grounding fault occurs in the system; if the single-phase grounding fault occurs, comparing a size of the three-phase voltage, judging that a lagging phase of a maximum voltage phase is a faultphase, and calculating an amplitude value and a phase of a fault phase voltage at this moment and an amplitude value and a phase of the zero-sequence current; comparing sizes of the fault phase voltage and a high-resistance grounding voltage threshold value, if the fault phase voltage is greater than the high-resistance grounding voltage threshold value, judging that a high-resistance grounding fault occurs, and according to a phase relation of the fault phase voltage and the zero-sequence current, judging whether a single-phase high-resistance grounding fault occurs in the circuit. The method is weak in dependence to a fault starting moment, and capable of completing single-phase high-resistance grounding fault detection of an isolated neutral system.

Description

technical field [0001] The invention belongs to the technical field of relay protection, in particular to a single-phase high-resistance grounding fault detection method of a distribution network. Background technique [0002] Most of the current distribution network systems are mainly based on ungrounded neutral points or grounded through arc suppression coils. Although single-phase ground faults do not constitute a zero-sequence current loop, the fault steady-state current is small, but with the increase of fault phase voltage , may cause insulation damage, thereby affecting the safe operation of electrical equipment, and even gradually develops into a phase-to-phase short circuit that leads to the expansion of the accident. Therefore, it is required to be able to accurately identify the faulty line and complete reliable grounding line selection. [0003] For non-high-impedance ground faults, the transient and steady-state signals are relatively clear, and effective fault ...

AI Technical Summary

Problems solved by technology

However, for high-resistance grounding faults, it is difficult to capture the fault starting time of high-resistance grounding, and it is difficult to locate the starting time of the data window by the line selection method based on transient quantities, and the transient signal is weak, so the accuracy of data calculation is difficult to guarantee; while the traditional The principle of steady-state zero-sequence voltage and current direction under the influence of transition resistance is prone to large phase deviations, which will have a great impact on the line selection results

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