Single-phase ground fault line search method

Abstract

The invention provides a single-phase grounding fault line lookup method. The method comprises steps: according to the PT voltage indication value of a bus, happening of grounding fault to a feed-outline of the bus is determined; the zero-sequence capacitive current of each feed-out line cable of the bus which is determined to have grounding fault is tested respectively and recorded; the test value of the recorded zero-sequence capacitive current of each feed-out line cable is compared and analyzed; and when the zero-sequence capacitive current value of the feed-out line cable of the bus which is determined to have grounding fault is larger than the zero-sequence capacitive current value of each of other feed-out line cables and the difference with the sum of the zero-sequence capacitivecurrent values of other feed-out line cables does not exceed a first set maximum difference, the feed-out line of the feed-out line cable with the maximum zero-sequence capacitive current value is determined to be the line with the grounding fault. The method can effectively judge a line with grounding fault, the lookup efficiency and the lookup accuracy of the fault line are improved, grounding fault is further eliminated as soon as possible, power line supply is restored, and the power supply reliability is improved.

Description

technical field [0001] The invention relates to the technical field of fault diagnosis and processing of a neutral point ungrounded power system, in particular to a method for searching a single-phase ground fault line. Background technique [0002] In the neutral point ungrounded power system, the power supply feed-out lines generally include cable lines and overhead lines. Single-phase ground faults in the power supply feed-out lines occur occasionally. When a single-phase ground fault occurs in the power supply line, it will cause other normal two-phase faults. The increase of the phase voltage poses a great threat to the insulation performance of the system, and it is easy to cause a two-phase short circuit accident. Therefore, the faulty line must be quickly detected and eliminated. The confirmation of single-phase grounding fault lines is generally carried out by the method of power outage pulling line by line and the method of fault line selection by installing a smal...

AI Technical Summary

Problems solved by technology

[0003] The method of power outage one by one is backward, which affects the reliability of power supply, and most of them have been gradually withdrawn from use

[0004] At present, the small current grounding line selection device has been widely used, but it is limited to the small capacity of the power supply system, the length of the power supply feed-out line, the system operation mode, the small current of the line zero-sequence capacitance, the influence of external interference, and the zero-sequence current transformer. Due to factors such as the type selection, accuracy, and non-standard wiring, the small current grounding line selection device often has false alarms and rejections, resulting in low line selection accuracy and seriously affecting the search for faulty lines.

Moreover, in order to save investment, two current transformers (CT: Current transformers) are mostly installed in feeder switch cabinets in many power distribution systems. The secondary current is communicated to the background monitoring computer through the microcomputer protection measurement and control device to realize the remote grounding alarm monitoring function.

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