Method for positioning faults of power distribution network based on amplitude analysis of three-phase current

Abstract

The invention relates to a method for positioning faults of a power distribution network based on the amplitude analysis of a three-phase current. The method comprises the steps of collecting the three-phase current of the power distribution network in real time, carrying out amplitude analysis on phase current of each phase before and after a single-phase earth fault once the single-phase earth fault occurs, carrying out deviation calculation by collecting phase currents with the same phase position at a starting moment so as to realize the amplitude calculation of a current phasor, simultaneously filtering the influences of load currents and interphase capacitance currents, and calculating a valid value of the change of each phase current. A monitoring device mounted at a certain point of a circuit can detect whether a detection point is located at a fault route by analyzing the change amount of the amplitude of the three-phase current. Based on the amplitude characteristics of the three-phase current after the single-phase earth fault occurs, a zero sequence current does not need to be synthesized, so that the analytical calculation quantity of a main station is reduced; and the method has relatively high practical values in the engineering.

Description

[0001] Patent field [0002] The invention belongs to the technical field of electric power automation, relates to the field of single-phase grounding faults in distribution networks, and specifically relates to a distribution network fault location method based on three-phase current amplitude analysis. Background technique [0003] The distribution network plays an important role in distributing electric energy in the power network. With the continuous expansion of the distribution network, the large-area use of power electronic devices and the access of distributed power sources make the structure of the distribution network increasingly complex. The single-phase-to-ground fault location accuracy in the distribution network has a certain impact. At present, my country's 6-35kV medium voltage distribution network generally adopts the method of ungrounded neutral point or grounded neutral point through arc suppressing coil, and the frequently occurring single-phase ground fau...

AI Technical Summary

Problems solved by technology

They may affect the location of faults because the electrical components are too small, the time delay is too long, or because the sampling frequency is too high and they are susceptible to external fluctuations

[0005] In recent years, an analysis method based on the transient current direction of the three-phase nodes of the line has been proposed. By comparing whether the direction of the three-phase transient current is the same, it is determined whether the point is a fault node, and by comparing the direction of the line current flow to determine whether the line is a fault. lines, but this method has misjudgments under the simulation of various actual engineering lines, and the accuracy cannot be guaranteed

[0006] To sum up, at present, various fault location methods in this technical field have certain shortcomings in the selection, calculation and logical judgment of electrical quantities, and the accuracy of the increasingly flexible distribution network is poor, so they cannot be widely used in the engineering field. to promote

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