A design of unbalanced insulation to improve the lightning performance of multi-circuit transmission lines

This paper proposed an unbalanced insulation design to prevent the multi-circuit flashover of multi-circuit lines. When multi-circuit transmission lines were struck by lightning, two or more circuits may flash over in the same time, which would bring a serious impact on the power grid. Traditional unbalanced insulation design to reduce the double-circuit flashover rate of double-circuit transmission lines also increases the total flashover rate when it reduced the double-circuit flashover rate. This paper proposed a new unbalanced insulation design method with a high insulation level using in multi-circuit lines, which can reduce the multi-circuit flashover rate with the total flashover rate not increased. And an improvement was made to the unbalanced insulation design with the using of arcing horns. The effectiveness of this design was simulated in a 220kV four-circuit transmission line in EMTDC.