Contingency Analysis and Risk Assessment of Small Signal Instability

Power system operating planning must determine adverse conditions that could affect the normal performance of the system. Load variations and contingencies could provoke these adverse conditions, which produce angular instability problems or voltage stability problems, among others. In addition, the short-term operating planning must evaluate risk of instability conditions for angular and voltage instability. This paper proposes a methodology to assess the angular instability risk due to load uncertainty based on modal analysis of the small signal analysis for short-term planning purposes. In addition, the risk assessment of angular instability is done for selected contingencies based on an eigenvalue variation contingency ranking proposed in this paper. The methodology is tested in the New England 39 nodes system.