MID-ATLANTIC UTILITIES UNDERGROUNDING PROGRAM CASE STUDY 53 1. DEFINING PROGRAM OBJECTIVES The starting point in the Utility Infrastructure Resiliency Playbook (Playbook) for building a potential resiliency program is to develop a clearly defined singular or set of objectives. The case study represents a combination of three Mid-Atlantic utility experiences in pursuing a resilience program that included significant undergrounding to introduce this concept and describe how they completed the analysis to craft a clearly defined set of objectives of their resiliency program. CHALLENGE Utility A experienced two large storms nearly back-to-back where 9+ days were necessary to get all customers back online. The outage time exceeded what was considered reasonable and the pace of restoration received public and regulatory scrutiny. The combination of regulatory and public scrutiny paired with Utility A executives’ desire to serve customers at the highest level caused an action to find a solution to long-duration outages. SOLUTION Engineering and operations analyzed historic performance during weather-related storm outages to identify potential solutions that would significantly impact outage duration – the primary objective. During historic analysis of restoration curve in a storm, when analyzing lines and equipment, not customers, it was identified that approximately 2/3 of lines and equipment are repaired in 1/2 of outage time; last 1/3 of lines and equipment are repaired in the last 1/2 of outage duration – many of the customers returned to service in the last half of the outage duration were in difficult to access areas or at the end of circuits. 2012/2013 analysis identified that 60-65% of outages were related to approximately 20% of the tap line mileage. RESULT Development of a series of undergrounding program options targeting 4,000 miles (20% of mileage) of single-phase tap lines responsible for 60% of outages with defined intention to significantly improve reliability performance and dramatically reduce outage duration. Modeling demonstrated that an up to 50% reduction in restoration time duration was possible.
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