New contingency ranking technique incorporating a voltage stability criterion

A new technique for ranking outages in power systems is presented. Traditional methods for ranking are limited to cases where the system state under the respective contingency condition can be simulated. Cases where a load-flow solution is unobtainable are unexplained. The new method presented can similarly rank all cases of contingencies, and cases that can cause voltage instability and system collapse are revealed. The information given by this new method is important because it can then attract the attention of the planning engineer to the problem of voltage instability that may exist in a power system. Thus power systems can now be designed to take into account the voltage instability problem as well as the normal security requirements