Determination of secure operating limits with respect to voltage collapse

A secure operating limit is the most stressed among a given set of operating points, such that the system can withstand specified contingencies. It is a general measure of security with respect to incidents, incorporating pre-contingency operator or controller actions and post-contingency corrective controls. The proposed approach deals with long-term voltage stability limits. It combines a dichotomic search with quasi steady-state simulation to compute these limits with the efficiency required by real-time applications. The limit search acceleration and contingency filtering issues are also discussed. Illustrative examples are given on the Hydro-Quebec power system.