Method for locating single-phase ground fault of a low current grounding system power distribution network

Abstract

The present invention relates to a method for locating single-phase ground fault of a low current grounding system power distribution network, including determining a total length L[total] and a total impedance Z[total] between two lines of M and N, and injecting signals when occurring a fault, when a P point between the M and N positions occurring a single-phase ground fault, systems of the two positions inject signals at the M and N position, and measures the amplitude of a return current signal as well as a phase difference between the return current signal and the injection voltage signal, after a line selection device has selected the fault phase; calculating a loop total impedance Z[M] grounded through the P point from the M and N ends, the modulo of the Z[N], and a phase angle Phi[M] of the Z[M] and the Z[N], according to |Z| = |U| / |I|, the measured injection voltage, the amplitude of the return current signal and the phase difference, a distance from the fault point P to the M position is further calculated through the following formula. By the method of the invention, it is easy to detect when the signal amplitude is strong, the attrition in the power distribution network is low, the algorithm is high, and the accuracy is high.

Description

technical field [0001] The invention relates to a fault location method, in particular to a method for automatic location of a single-phase ground fault point in a power distribution network of a small current grounding system. Background technique [0002] my country's 6-66kV power distribution network mostly adopts the operation mode of small current grounding system. Single-phase ground fault is its main fault type. Once a single-phase ground fault occurs, the traditional method is to inspect each branch line manually, which is time-consuming and laborious; moreover, a large number of switching operations are required, which brings great inconvenience to the normal operation of the power grid and production and life. At present, there are several domestic positioning methods: Traveling wave method: inject high-frequency traveling waves at one end of the faulty line, and calculate the fault distance according to the time and wave speed of the traveling waves returning fro...

AI Technical Summary

Problems solved by technology

The disadvantage is that the voltage and current recorded by the wave recording equipment are weak and difficult to detect

The positioning algorithm needs to solve the iterative process, and the result is prone to non-convergence or pseudo-roots

Algorithms for solving differential equations are susceptible to transition resistance and the way the system operates

None of the current methods can satisfactorily realize the automatic location of single-phase-to-ground faults in distribution networks

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