Influence of different coupling ground wire erecting mode on lightning withstand performance for multi-circuit transmission line in a tower

Considering that multi-circuit transmission line in a tower has a smaller occupied area and a larger transmission capacity, it has become very important for electric power transmission. Nowadays transmission lines put into operation at home and abroad mostly are multi-circuit transmission line in a tower, which can increase the risk of simultaneous lightning strike-back outage. Mounting coupling ground wire(CGW) can enhance the strike-back lightning-withstand level of transmission line effectively, especially when the soil under tower has a great electrical resistivity so it´s difficulty to lower the grounding resistance, advantages of CGW will be more notable. A lightning strike model of double-circuit transmission line in a tower with different CGW mounting height is modeled based on EMTP in this paper, and transmission line´s lightning-withstand levels with different CGW mounting height are analyzed, then by their effects being compared, the optimum CGW mounting method is given, which can contribute scientific basis and reasonable suggestion to transmission line lightning protection.