microgrid
In 2014 there were 3634 outages in the US electric system according to the Eaton Blackout Tracker. It affected in total over 14 million people. On average close to 4000 people were affected per outage, which on average lasted 43 minutes. 30 % of the outages were caused by weather and trees. 28 % were caused by faulty equipment and/or human error.
Almost all outages were at the distribution system level, Outages at the transmission level are very rare, but when they happen the consequences are bigger, affect more people and take longer time to restore. The Northeast Blackout in August 2003 hit 55 million people in United States and Canada. One month later the Italy Blackout had also about 55 million people in Italy, Switzerland, Austria, Slovenia and Croatia losing power. As recent as in March this year 90 % of Turkey with 70 million people lost their power. The largest blackout so far was in July 2012 affecting half of India and 620 million people. In fact the grid collapsed for a second time in two days.
2003 Northeast Blackout. Satellite pictures before and after the blackout. National Geophysical Data Center (NOAA/DMSP).
On March 11, 2011, The Great East Japan Earthquake hit very hard and took out much of the electric power. However, there were pockets that managed to provide power and heat during the 2 – 3 days it took to restore the electric grid. One of such pockets was at Sendai City in the Tohoku district.
Sendai microgrid was initially designed in 2004 as a demonstration project. After the study was completed in 2008 the microgrid continued in operation. It is located on the campus of Tohoku Fukushi University. Normal load, including a hospital, is about 700 kW. The microgrid has two gas fired generators, each at 350 kW, a 200 kW fuel cell and a 50 kW PV array.