System Modernization and Reliability: A Transition to Underground

With continually decreasing costs for underground distribution construction coupled with increasing outage and restoration times as a result of strong weather events, installing underground primary distribution is becoming a more frequently utilized method to decrease outages and improve system reliability. An analysis of detailed outage data indicates overhead circuit reliability cannot always be improved significantly through simple system hardening. Increasing storm damage, along with higher demands for reliability from customers, public utility commissions, and other regulatory agencies have led to the need to improve distribution system reliability performance. Wisconsin Public Service Corporation is currently in the process of converting a significant portion of its overhead electric distribution system to underground for reliability improvement purposes. The impacted areas of the distribution system are primarily concentrated in the heavily forested northern areas of Wisconsin Public Service Corporation's service territory. Beginning in 2014 and spanning a 5 year period, Wisconsin Public Service Corporation began replacing 1000+ miles of overhead distribution with underground facilities at a pace of approximately 200 miles per year. How does one design such a sophisticated and specialized system improvement program that incorporates environmental concerns, efficient circuit design, large scale customer engagement, and a focus on the circuits with the largest reliability issues? How could one prioritize the various segments of lines on the electric distribution system to achieve optimal results?