Novel directional comparison protection for distribution lines

Abstract

For quickly clearing up a fault of distribution lines, which concerned with complex structure and operating modes, a directional comparison protection is necessary. The paper evaluated the traditional directional relay through modeling a typical distribution system and presented a novel negative sequence directional relay and a new directional comparison protection scheme specially designed for distribution systems. In the relay and the protection scheme, a particular negative sequence component has been constructed to solve the problem that there is no negative sequence component in a symmetrical fault case so that they could operate correctly in both asymmetrical fault and symmetrical fault. Extensive EMTP simulation studies proved that the protection schemes are able to provide fast and reliable responses for all fault conditions. In particular, they are able to give correct responses adapting to the change of system operation conditions, including the changing of system configuration, power flow direction, and source and tapped-offload conditions. distribution lines, negative sequence directional relay, directional comparison protection

Evaluation of directional relay algorithms in the presence of FCL

“…In [28], change in phase angle difference between negative sequence of post-fault and pre-FCs has been utilised for fault direction identification. In [29], phase angle difference between negative sequence of voltage and current is used for this purpose. Negative-sequence components are not generated in all fault types, and so in this situation relay cannot detect direction of a fault.…”