Differential protection of mutually coupled lines in modal domain using synchronized measurements

A new current differential protection scheme for high voltage double circuit transmission lines in the modal domain is proposed in this paper. This method is based on decoupling the mutually coupled lines using modal transformation matrix. Synchronized current and voltage phasors from both the ends are utilized and converted to modal values. The lines are modeled with equivalent-π model. Current differential protection is applied in series branch current of equivalent-π model so that line charging current is compensated. The simulation results in ATP claim the security and dependability of the proposed scheme.