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

A single-phase ground fault and small current grounding technology, applied in the direction of the fault location, can solve the problems of unsatisfactory automatic positioning of the distribution network, weak voltage and current, and non-convergent results, so as to achieve convenient and flexible implementation and reduce production Impact of life, low loss effect

CN101545944AInactive Publication Date: 2009-09-30HEFEI COMEON ELECTRONICS TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2009-09-30
Estimated Expiration
Not applicable · inactive patent

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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.
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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...

Examples

Embodiment Construction

[0020] The distribution line between M and N may have a single-phase ground fault. The steps of positioning using the method described in this patent are as follows:

[0021] 1. Determine L 总 and Z 总 : Obtain the line length L between M and N through known line parameters 总 , and the total impedance Z of the line between M and N 总 . Z 总 It can also be obtained by the following method: injecting a voltage signal U at M ground i M , directly ground the N ground with metal. The injected signal returns to the M ground directly through the ground at the N ground, forming a loop. Measure the return current I of M ground CT M , and the phase difference of voltage and current . According to |Z|=|U / |I|, combined with the magnification of PT and CT, |Z can be obtained 总 |, and L 总 and Z 总 It is the parameters required for positioning calculation, and they are stored in the host computer of the positioning system.

[0022] 2. Measurement of double-terminal voltage inje...