Adaptive distance relay algorithm for double circuit line with series compensation

With the onset of fault, nonlinear operation of Metal Oxide Varistor (MOV) in series compensated line introduces error in distance estimation. Distance relay reach accuracy depends on several factors. Mutual coupling effect in double circuit line is highly nonlinear and depends on circuit configuration, fault resistance and remote source infeed. This may lead to inadvertent operation of distance relay for faults outside the operating zone. Variations in system condition, effect of shunt capacitance effect and fault resistance influence distance relay healthy operation. Adaptive setting in digital platform is a greater advantage to estimate the change-in system condition and modify the relay characteristics using the recent information. This paper presents an adaptive algorithm for protection of double circuit series compensated line using local end information. The adaptive algorithm is derived for single-line-to-ground fault condition. A 400 kV two source system is considered and simulated using EMTDC/PSCAD.