Back flashover analysis improvement of a 220 KV double circuit transmission line

The objective of this paper, is to design a 220kV double circuit transmission model, which includes six insulator strings with six cross arms and other components of the Transmission line i.e phase and ground conductors, line towers associated grounding systems with a surge of 100kA, 4/10 μs. The transmission line and back flashover event was modeled by frequency dependent fast front transient models due to the nature of higher frequency dependency of lightning strokes typically ranging from 1KHz to 30 MHz. Tower with two OHGW was taken in this work. Back flash over mechanism is modeled and triggered to the existing system by an external control module with powerful electrical tool PSCAD/EMTDC. Metal Oxide Transmission Line Arresters were used in this work as a solution for the back flashover. However, considering acceptable probabilistic failure as one outage per year per 100km line length, and suggested basic insulation level (BIL) of 1050kV, the arrester rating was calculated to be 196kV and its parametric determination for a one column arrester with an overall length of 1.45 meters is done. Simulation is carried out by placing Metal Oxide Arrester in each phase and recovering the string voltage without causing violent impact to the power grid.