Achieving Resilience at Distribution Level: Learning from Isolated Community Microgrids

Increasing power system resilience at the distribution level is crucial due to the negative social impact of blackouts, as the undesired consequences get worse the longer the system restoration takes. Statistical records demonstrate that system recovery times after high-impact, low-probability events (e.g., earthquakes, tsunamis, and floods) are often faster for generation and transmission segments than for the distribution system. During the 2010 Chilean earthquake (8.8 Mw on the Richter scale), for example, the distribution system in the most affected area (almost 1.1 million customers) was not totally back in service until two weeks after the first major seismic event. In contrast, the transmission system rapidly recovered, with most of the bulk system buses re-energized by the end of the first day and the remainder during the second day. Additional installed generation capacity and repairing minor damage to most of the affected generation plants allowed for the recovery of most of the supply within a few days. Only 6.1% of the installed generation capacity required major repairs (which took up to six months to complete).