Investigation into a double-circuit line fault using the mutual coupling impedance

This paper investigates a double-circuit line fault with non-selective tripping caused by the parameterization of the relay based on inaccurate/insufficient knowledge of the line impedances. Analysis of the fault is based on the measured line impedances and the simulation/system-based testing using RelaySimTest. An appropriate procedure was adopted and documented to measure the line impedances of double-circuit lines in a minimally invasive manner.