Circuit protection order component phase selection method using both end information

Abstract

The invention relates to a phase selection method for line protection sequence components using double-terminal information. First, synchronous sampling is performed on the phase currents of the own side and the opposite side of the line at a predetermined sampling rate, and the sampled value of the opposite side phase current is transmitted to the current side; Secondly, calculate the differential current vector of each phase of the above sampling results, and extract the positive sequence, negative sequence, and zero sequence components of the differential current based on phase A; then compare the phases of the negative sequence and zero sequence components of the differential current: , is A or BC two-phase ground fault; , is B or CA two-phase ground fault; , is C or AB two-phase ground fault; it is characterized in that it also includes a determination step: according to the positive sequence, negative sequence, zero sequence of the differential current The size of the sequence component is determined for single-phase and two-phase ground faults in each partition. If so, it is a single-phase ground fault; otherwise, it is a two-phase ground fault. This method uses differential current to judge, the principle is simple and reliable, it is not affected by the system operation mode, the sensitivity is high, and the phase can be selected accurately even in the event of a conversion fault.

Description

technical field The invention belongs to the technical field of power system automation, and relates to a phase selection method for line protection sequence components using double-terminal information. Background technique When faults occur on high-voltage and extra-high-voltage transmission lines in power systems, single-phase reclosing methods are widely used in high-voltage systems in my country. Due to the need for phase-selection tripping, phase-selection components have become important components in high-voltage protection devices. Traditional phase selection elements can only be judged by single-ended voltage and current. Generally, there are phase selection elements for sudden change in phase current difference, impedance phase selection elements, and sequence component phase selection elements for single-ended quantities. These phase selection elements are only The use of single-ended quantities is often greatly affected by the operating mode. In addition, in so...

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Problems solved by technology

At present, the method of segmenting the sequence current and comparing the measured impedance is used as a phase selection element during the oscillation blocking period. During the oscillation blocking period, the measured impedance (especially the non-fault phase) is greatly affected by the system oscillation, and the measured impedance comparison is an auxiliary element. Single-phase grounding will be misjudged as two-phase short-circuit grounding fault, and two-phase short-circuit grounding will be misjudged as single-phase grounding. Its ability to withstand transition resistance is also very poor, which is a major hidden danger in the current high-voltage transmission line protection

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