A new directional relay based on the measurement of fault generated current transients

This paper presents a new principle in directional relaying in which the fault direction is determined based on a comparison of the spectral energy of the fault generated high frequency current transient components. In this scheme, a current transient detection unit, which is interfaced to the CTs on each of the output lines connecting the busbar, is employed to capture the fault generated transient current signals. The transient signal captured from each line is first integrated (based on a small window of information) to obtain its spectral energy; the level of the energy entering the busbar is then compared with that leaving it, to ascertain the direction of the fault. It is shown that the detector is also able to make correct discrimination when a fault occurs on the busbar. Simulation studies were carried out using the EMTP software. The faulted responses were examined with respect to various system and fault conditions