A power system has become fragile due to climate change. The weather events, for example, Hurricanes Katrina, Sandy in the US and Tohoku Earthquake in Japan, caused enormous economic losses and have imprinted people in making the power system more resilient under natural disasters. In order to evaluate the impacts of natural disasters on the power system, resiliency is necessarily needed. But in contrast to power system reliability, power system resiliency is less known relatively and there is no widely accepted concept for itself. Therefore, this paper shows the fundamental concept for power system resiliency, some reasons those make power system vulnerable including natural disasters, and the method to evaluate the resiliency.

Resiliency,power system,Critical Infrastructures,Extreme Weather,Natural Disasters