After power failure in US and Canada in 2003, people have
paid close attention to system security and reliability. The
study of the probability of power system security and stability
is very important. Many uncertain factors exist in power
system, and the exploitation and development of tools
considering these random factors meets the actual needs. The
general probabilistic load flow [1] calculation only considers
the randomness of generator and load. However, it is ignored
that random fault lines and correlation existing among nodes
and lines in real system.