Security Region Based Probabilistic Security Assessment of Power Transmission System a Basic Concepts

Without accounting for uncertainty factors in power system the security measure of traditional deterministic security assessment is uncertainty itself. So the traditional deterministic security assessment should be replaced by probabilistic steady-state and dynamic security assessment. The paper presents a security region based probabilistic steady-state and dynamic security assessment framework. In this framework, not only constraints of transient stability, static voltage stability, node voltages and line currents, but also uncertainties of power injections in load buses and in generator buses, uncertainty of load model in stability analysis and the probabilities of critical contingencies (determined by failure rates of system elements, weather forecasts, storm and lightening tracing) are considered. The mathematic descriptions of security regions make it easy to take account of the uncertainties of power injections and load model of stability analysis. The research results of probabilistic security assessment can be applied in making decision of preventive control and emergency preparation. Test results on a real transmission system of China have shown that the presented method is efficient