A Risk-Assessed Approach to Overhead Line Corridor Clearance Management

Abstract

Ensuring public safety and the continuity of supply of electricity to customers are essential aspects of overhead line (OHL) asset management. Maintaining the required electrical clearance limits of conductors from the ground, vegetation, roads and other infrastructure within the line corridor is a vital part of this process. Such is the importance of adequately assessing clearances from terrain, obstacles and vegetation that may pose safety risks to members of the public and threaten network reliability, an approach was developed to allow the prioritisation of the most urgent clearance infringements in each of these categories. This approach risk-assesses the magnitude, extent and consequence of clearance infringements and categorises them accordingly. Practical challenges associated with the basis for vegetation clearance requirements from OHLs were also identified during this process. Vegetation clearance requirements were reviewed and priority-based clearance zones were defined based on conservative assessments of vegetation growth gathered over consecutive years. A case study considering a heavily loaded 110 kV OHL in Ireland demonstrated how the revised approach was successfully utilised to identify clearance issues over terrain, obstacles and vegetation along an OHL corridor.