Identification of cascading failures based on overload character of transmission lines

The tripping of transmission lines for overload or failure will cause transference of vast load, then further cause a series of lines and generators to trip. It is greatly relevant to serious failures, particular to the cascading outages. This paper investigates the mechanism of cascading outages based on the characters of overload in lines, and proposes a method for forecasting sequential events of cascading outages. In this method, overload severity index is defined to judge the loading status of transmission lines, and identify the set of overload lines. Furthermore, the paper uses the drawing theory to zone networks topology according to load flow, thereby finds the set of hidden failure lines. Finally the correction of this method is verified through real example.