A novel distance protection algorithm for long-distance transmission lines

In this paper, a novel distance protection algorithm for long-distance transmission lines is introduced to cater for the problems of the influence caused by distributed capacitance in the long-distance transmission lines and the low fault resistance tolerance by traditional distance relays. To tackle the problem caused by the distributed capacitance in the transmission line, the observing point is moved to the setting point from the relay point by using the Bergeron equations to improve the accuracy of measurement when a fault occurs around the remote terminal. Meanwhile, to tackle the problem of low fault resistance tolerance ability by traditional distance relays especially for phase-ground faults, a new distance protection algorithm concerning the impact of the fault resistance and the opposite system is proposed at the observing point using the information extracted by matrix pencil algorithm. At last, data from PSCAD simulation software demonstrate that the proposed distance protection algorithm can trip the breaker correctly for an internal fault even with high fault resistance and will not overreach for an external fault.