Simulation-Based Study of Earthing Switch and Interrupter on Dominion Energy's Compact Corridor

Dominion Energy is installing new transmission lines to meet the increasing load demand. In a corridor spanning over 55 kilometers, a new 500kV/230kV monopole structure will replace existing structures. This structure will accommodate more than 20 existing and newly installed transmission lines. Up to five transmission lines can be placed within the 57-meter span of the corridor. Due to the corridor's long-distance and narrow width, induced voltage and current on de-energized lines will significantly increase, resulting in extended arc reach during current interruption. To ensure field crew safety, earthing switches and interrupters need to be installed to interrupt induced resistive and/or capacitive currents. This paper summarizes the results of a Dominion study of earthing switches and interrupters. Using PSCAD simulation, we analyzed induced voltage and current in the compact corridor and estimated arc reach, which informed the need for earthing switches. Transient recovery voltage simulations were also studied to evaluate the interrupters' capacity.