A Dynamic Approach for Assessing Lightning Risk to Electricity Transmission Networks Considering Environmental Factors

This paper investigates the lightning performance of UK transmission networks at an hourly time scale, explicitly incorporating the influence of environmental operating conditions. The analysis is structured into two main components. First, a baseline lightning risk score is established using the conventional shielding failure flashover rate (SFFOR) evaluated on an hourly basis. Second, a set of correction factors is introduced to modify the baseline risk, accounting for time-varying operating conditions, including wind-induced insulator swing and spatially clustered lightning activity. The wind load effect on insulator swing is analysed to quantify its impact on the effective shielding performance of transmission towers. In parallel, a density-based spatial clustering of applications with noise (DBSCAN) method is applied to raw lightning flash data to derive regional, hourly flash density inputs. A case study focusing on a day with intense lightning activity is conducted for transmission assets in England. The results demonstrate the impact of environmental factors on hourly lightning performance and provide guidance for refined lightning risk assessment of transmission assets.