The Power System Voltage Security Assessment Based On Risk Theory

Alone with the strategy of large grid, high-capacity machine unit, UHV long distance power transmission taking into effect, the problems of security about power system will loom large. As a traditional method, the deterministic method is currently applied in power system security analysis, this method can provide the accurate results for deterministic operating condition. But it can't reflect the probability attribute of load fluctuation; the fail of component and so on in power system. Because of the deficiency of traditional method, the risk assessment method is gradually used in power system security analysis. The risk assessment method takes the occurrence probability and effects of accidents into account comprehensively, can do the entire analysis and research of power system.In this paper the risk assessment method is applied in security analysis of power system, first the definition of risk and the research status of power system security analysis based on the risk assessment method are presented, next, the disadvantage of traditional method are pointed out. Then some researches on static voltage collapse, transient voltage stability which considers many uncertain factors and voltage collapse caused by cascading failure are done. In the end an on-line voltage security assessment system framework based on the risk index and the function of each module are proposed, because of the proposing of the framework, directions to be deepening are pointed out.