Fault nature identification method for three-phase adaptive reclosing of lines with shunt reactors

Abstract

The invention relates to a method for recognizing properties of three-phase adaptive re-closing faults of lines with parallel reactors. By the aid of the method, problems of different application ranges of existing fault property criteria and high quantities of influence factors on the existing fault property criteria can be solved. The method includes firstly, sampling the magnitude of currents of the single-ended parallel reactors after three-phase tripping occurs, and acquiring corresponding differential-mode components by means of phase-mode transformation; secondly, computing frequencies (periods) of the differential-mode components according to parameters of the lines; thirdly, analyzing waveforms of instantaneous values of differential-mode currents in a period of the differential-mode components. Besides, only attenuation direct-current components are available in the differential-mode currents when permanent faults occur, only attenuation periodic components are available in the differential-mode currents after instantaneous faults occur and then arcs of the faults are blown out, accordingly, novel criteria applicable to recognizing the properties of the phase-to-phase faults during three-phase adaptive re-closing can be provided by the aid of waveform characteristics of the differential-mode currents under different fault property conditions, and arc blowout moments can be identified. The method has the advantages of few influence factors on fault property discrimination and high sensitivity.

Description

technical field [0001] The invention belongs to the technical field of power systems, and in particular relates to a method for identifying the nature of a three-phase adaptive reclosing fault of a line with a shunt reactor. Background technique [0002] At present, the automatic reclosing technology is basically adopted in the transmission lines at home and abroad, which plays a vital role in ensuring the stable operation of the power system. However, while automatic reclosing has brought huge economic benefits, it has also brought negative effects to the power system. Because the fault nature of the transmission line is divided into transient fault and permanent fault, if it overlaps with the permanent fault, it is equivalent to the power equipment being impacted by the fault current again, which will shorten the life of the power equipment. In order to reduce the loss of the power system, it is very important to judge the nature of the fault before reclosing. [0003] A...

AI Technical Summary

Problems solved by technology

Since there is very little information that can be extracted from the line after a three-phase trip, the research on three-phase adaptive reclosing is difficult, but some achievements have been made, mainly as follows: ① Based on the method of line recovery voltage, the discrimination accuracy of this method To a large extent, it depends on the measurement accuracy of the voltage transformer on the line side, and many lines have no voltage transformer or only one phase voltage transformer on the line side; ②The method based on the high frequency protection channel needs to rely on high frequency protection channel, and there is a possibility of misjudgment for phase-to-phase faults that do not include the processing phase; ③ The method based on fuzzy neural network requires a large number of training samples, and its reliability needs to be tested; ④ The method based on shunt reactor current , including: the identification method based on the inductance and capacitance parameters, but the calculation process involves differential and integral operations, which will bring large errors when performing approximate processing; the method based on model identification and current differential, when the transition resistance is large, the discrimination The results have a great influence; the method based on the separation of the frequency and amplitude of the free oscillation component requires a high sampling rate, and the discrimination is low; the above method based on the shunt reactor current needs to use two Terminal shunt reactor current

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