ABSTRACT
However, as a complex automatically controlled systems, HFs in protection systems should be multiple. One HF has an influence with other HFs and different HFs occur at different time points in the action of a protection relay. The multiple HFs in protection system have brought some new problems in the analysis of N-k contingencies. Different HFs may come to different N-k contingencies. The problems can be reduced to two aspects. One is the method to calculate the probability of N-k contingencies. The other one is the identifying of N-k contingencies in power system.
