HIGH-RESISTANCE FAULTS ON A MULTITERMINAL LINE - ANALYSIS, SIMULATED STUDIES AND AN ADAPTIVE DISTANCE RELAYING SCHEME

The presence of a T-connection to a third terminal can drastically aff ect the performance of a distance relay at the other terminals. Fault resistance, especially high fault resistance, makes this problem more severe and complicated. Detailed analysis of the apparent impedance fo r these cases as seen from the relaying point is derived and, based on extensive simulations of the infeed/outfeed and fault-resistance effe cts on the relay characteristics, an adaptive distance relaying scheme is proposed. A microprocessor based distance relay using this new tec hnique can quickly respond to very-high-resistance faults with maximum coverage of the protected line. The validity of this new scheme has b een confirmed by real-time testing on a prototype hardware scheme.