Anatomy of power system disturbances : importance sampling

Abstract The study of North American Reliability Council reports indicate that protection systems frequently play a role in the sequence of events that lead to power system disturbances. While it is generally believed that the self-monitoring and self-checking feature of digital relays will reduce the probability of such relay involvement, there has been no qualitative evaluation of the effect of such a reduction. The technique of “importance sampling” is used to make this problem more manageable. Using the New England 39-bus system, it is shown that reducing probability of relay involvement has a significant influence on overall system reliability.