
The robustness of power systems can be ensured by steady state security regarding power grid contingencies based on a steady state model. An overview of contingency analysis methods which consider steady state security of power system with stability margin index is provided in this paper. Traditional methodologies of contingency analysis for power systems, steady state security include full AC power flow analysis, approximate methods and contingency ranking. Methods are investigated to speed up the full AC power flow algorithm and improve the accuracy of approximate techniques. The indices for contingency ranking, such as performance index and voltage stability margin, are discussed in detail.