Case Study – Sharing an AC Mitigation System

Abstract An alternating current (AC) interference study was conducted in 2019 following a utility development project that included constructing a new substation and upgrading approximately 24 km of new AC transmission powerline sections in Alberta, Canada. The study comprised six transmission powerlines owned by one utility and eight pipelines owned by two different operators. The modelling results showed touch voltage hazards under steady-state and fault conditions and susceptibility to AC corrosion and coating stress above the established limits in the unmitigated state. A shared AC mitigation system was designed to eliminate the hazards caused by AC interference on all eight pipelines. This approach reduced overall mitigation requirements, number of site visits, construction footprint, environmental impact, and project costs. This paper describes the mitigation system's design, installation, and commissioning and discusses the benefits of a shared AC mitigation system approach.