Improving parallel line distance protection with adaptive techniques

Performance of distance protection on parallel lines is negatively affected by mutual coupling effect between lines. The mutual coupling effect of a parallel line causes errors in the distance measurement of a conventional distance relay, which leads it to either to overestimate or underestimate the fault distance depending upon the system condition, the fault location, the bus configuration and line operating status. This paper shows the feasibility of achieving an optimal performance of a distance relay on parallel lines by using multiple locally available signals and applying adaptive techniques, without the use of any remote signals and/or additional system information