A unified model and automatic contingency selection algorithm for the P and Q subproblems

A new approach to automatic contingency selection (ACS) and ranking is presented in this paper. ACS for the P and Q subproblems is solved by a unified network flow model and algorithm. It is based on the existence of weak coupling between real and reactive quantities in power systems. The performance indices to assess the severity of contingencies are defined as the total real and reactive load to be curtailed. The proposed model and its algorithm are examined numerically with IEEE 5-bus, 14-bus, 30-bus, 57-bus and 118-bus test systems on an M-340 computer.