The Automatic Correction of Selective Action of Relay Protection System against Single Phase Earth Faults In Electrical Networks of Mining Enterprises

摘要

Nowadays current protection against single-phase short circuits in electric networks 6-35 kV of the mountain entities work for the earth not selectively that leads to unjustified shutdowns and idle times of electric equipment. The reason for that presence of transitional resistance in a contour of the zero sequence which lowers sensitivity of protection. The purpose work is increase in efficiency of action protection against single-phase short circuits on the earth in the conditions of inconstancy parameters of a contour current the zero sequence. The main objectives of this work were development of structure system automatic increase in selectivity of action protection and justification her working capacity in the conditions of big transitional resistance in the place of short circuit on the earth. The algorithm of action the offered system provides assessment of size transitional resistance and the subsequent automatic correction of a signal current the zero sequence taking into account incompleteness of short circuit on the earth. It allows to increase sensitivity and selectivity of action protection. Check operability an algorithm of action was carried out by means of computer modeling in the environment MatLab Simulink. Results of the carried-out tests the offered system have confirmed high stability of reliable functioning of protection against single-phase short circuits on the earth regardless the size of transitional resistance in the place short circuit. Use developed system of automatic correction selective action of the protection against single-phase short circuits on the earth which is reliably functioning in case different types of short circuit allows to minimize damages because of availability single-phase short circuits in distribution networks 6-35 kV of the mountain entities.