Performance against Direct Lightning on 10kV Overhead Distribution Lines with Counterpoise Wires

This paper investigates the lightning performance on 10kV overhead distribution lines grounded with counterpoise wires under extremely low soil conductivity. A partial element equivalent circuit model considering lossy ground is used for surge analysis, and the Monte Carlo method is adopted for evaluating the flashover rate. It is found that under extremely low soil conductivity, the simple vertical grounding rod is not effective in lightning protection, while the performance is significantly increased with extended counterpoise wires. The single-row counterpoise wire with a length of pole span performs best among the schemes of concern. The single-row counterpoise wire with a half-length of pole span is a competitive one, due to a half-cost reduction but a competitive performance with a difference of less than 9%. With the same total wire length, the scheme of single-row counterpoise wire is slightly better than the parallel-row arrangement. If a higher lightning protection level is required, the improvement could be achieved by increasing the CFO level or shortening the span of two adjacent surge arresters, since increasing the length of counterpoise wire is not cost-effective.