Method for discriminating internal and external faults on basis of transverse faults of double-circuit lines of same towers

Abstract

The invention discloses a method for discriminating internal and external faults on the basis of transverse faults of double-circuit lines of the same towers. The method includes steps of 1, judging whether fiber channels are used for pilot distant protection or not, carrying out a step 2 if the fiber channels are used for pilot distant protection or carrying out a step 4 if the fiber channels are not used for pilot distant protection; 2, judging whether bit error rates of the fiber channels are smaller than set values or not, carrying out a step 3 if the bit error rates of the fiber channels are smaller than the set values or carrying out the step 4 if the bit error rates of the fiber channels are not smaller than the set values and are smaller than pilot distant threshold values; 3, acquiring data at two ends of each fiber channel, computing differential flow, discriminating that faults are the internal faults if differential criteria are met by the differential flow and brake currents, or discriminating that the faults are the external faults if the differential criteria are not met by the differential flow and the brake currents; 4, establishing pilot-direction zero-sequence and negative-sequence integration direction criteria; 5, discriminating forward and reverse faults of zero-sequence direction protection; 6, discriminating pilot-direction zero-sequence and negative-sequence integration directions. The method has the advantages that protection misoperation can be effectively prevented, the stability of integral electric power systems can be improved, and safe and stable operation of power grids can be effectively guaranteed.

Description

technical field [0001] The invention relates to a method for distinguishing internal and external faults based on transverse faults of double-circuit lines on the same tower. Background technique [0002] For double-circuit lines on the same tower, when a disconnection fault occurs on one circuit line, a zero-sequence voltage zero-crossing point will be generated on the other circuit line. If the traditional compensation method is used, over-compensation may occur, making it originally judged to be reversed. The zero-sequence direction relay is judged to be positive, and both sides are the same, resulting in zero-sequence longitudinal connection malfunction. [0003] Such as figure 1 As shown, when a disconnection fault occurs on the first line of the double-circuit line on the same tower, in the zero-sequence fault additional network, it is equivalent to connecting a voltage source in series at the fault point. At this time, the healthy line of the other loop will be subj...

AI Technical Summary

Problems solved by technology

At this time, the healthy line of the other loop will be subjected to double coupling effects of electricity and magnetism at the same time, and the electrical coupling will make the polarity of the zero-sequence voltage at both ends of the healthy line opposite, such as figure 1 middle for positive polarity Negative polarity, so there will be a zero-sequence voltage zero-crossing point on the healthy line

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