Steady-state error estimation in distance relay for single phase to ground fault in series-compensated parallel transmission lines

Distance relay zone reach setting demands for the knowledge of transient and steady-state error to ensure secure operation. This study addresses the estimation of steady-state error which will be encountered by conventional distance relay protecting series-compensated parallel transmission lines (SCPTLs). Different factors like, remote-end in-feed, varying levels of series compensation and fault resistance are taken into consideration to arrive at generalised expressions for transposed SCPTL. These expressions can be used to estimate steady-state error in positive sequence impedance estimation which will be encountered by healthy and faulty line relays, both with and without mutual compensation. Comprehensive analysis is done using two different tower configurations for each of the above-mentioned factors, both with and without mutual compensation to analyse healthy and faulty line relay behaviour.