Improving Transmission Line Reliability through Lightning Design

In today's competitive electricity market, double circuit transmission line construction is commonly used to reduce capital cost, and to provide more efficient energy transfer on valuable transmission line easements. These advantages come at the expense of reduced reliability from having two high capacity circuits on one structure. This paper looks at modelling techniques for lightning performance of transmission lines. It focuses on the probability of double circuit outages resulting from lightning, which is the predominant outage mechanism in Queensland. Three double circuit transmission lines ranging from 132 kV to 330 kV are modelled using several lightning design packages, and the results compared to recorded lightning performance data. Several methods for improving the lightning performance of transmission lines are discussed.