Transient Stability Risk Assessment Based On Evidence Theory And Utility Theory

It is increasingly important to ensure the safety and stability of the power system, while the nation-wide grid becomes more and more complex. In recent years, the huge blackouts have caused enormous economic losses, both in China and other countries. The power grid safety is widely concerned around the world. The summary of the traditional methods of power system security analysis is reviewed in this paper and a new risk-based security analysis method of power grids is introduced. The possibility of the line fault (PLF) is treated as a fuzzy number and the model of PLF which bases on the evidence theory is set up. The model takes the influence of the external environment on the power grid into consideration. The utility function is used to define the severity of the fault. A composite system transient risk indicator is obtained by integrating the various indicators of risks, which base on the entropy and the analytic hierarchy process (AHP). The composite indicator can sensitively reflect the trend of the line fault risk change. Such simulation is in accord with the practical operation of the power grid. Finally, a power grid of a city is chosen as the assessment example, in order to test the validity and effectiveness of the method of the power system transient risk assessment.