High roltage circuit high resistance grounding protective method

Abstract

The invention relates to a high-resistance grounding protection method for high voltage circuit, which belongs to relay protection field. The method is: the wavelet function is used as analysis tool; the mother line triphase voltage, circuit triphase current and zero series voltage and current are used as reference quantity of electricity, the connection way between the voltage mutual inductor and the current mutual inductor uses standard connection; the mold maximal value of triphase current and zero series current after wavelet analysis is used as starting device by means of 'or'; the mold maximal value of the line current or zero series current after wavelet analysis is used as starting element; the mold maximal value of the triphase other line voltage is used as the rule of interference resisting; finds out the grounding failure phase according to if the mold maximal value character is consistent or not; the zero series current and the voltage polarity are used as direction judgment accordance. The invention can judge if there has single-phase high-resistance grounding failure in the electric line, it has direction performance, and uses the mother line voltage as interference resisting accordance, it has a high protection sensitivity and reliability.

Description

technical field [0001] The invention relates to a high-impedance grounding protection method for transmission lines, in particular to a high-voltage line high-impedance grounding protection method based on wavelet polarity discrimination. It belongs to the field of relay protection. Background technique [0002] In the large ground current system of 110kV and above, the single-phase ground short circuit accounts for the vast majority (about 90%). In mountainous or forest areas, invisible single-phase high-resistance grounding faults are often caused due to insulator flashover and lightning strikes. At this time, the fault current is generally small, the voltage drop is small, and the impact on the normal operation of the load is small, which increases the difficulty of large resistance grounding detection. The presence of high-resistance ground faults may lead to more serious faults in power systems. It is important to detect and eliminate such faults in time. [0003] T...

AI Technical Summary

Problems solved by technology

However, in practical applications, its protection effect is greatly affected by the number and distribution of the neutral point grounding, and when the line is very short or the operation mode changes greatly, the sensitivity will not be enough.

In addition, the wide application of single-phase reclosing makes the implementation of zero-sequence current protection more complicated

As for the system where the neutral point is not grounded or grounded with high resistance, due to the relatively small current of the grounding capacitor, there is no relatively complete protection method so far.

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