Survey of power system voltage stability study

Voltage instability manifests itself in a dramatic drop of transmission system voltages,which may lead to system disruption. The voltage instability phenomena is described and explained. Approaches to voltage stability study based on static and dynamic means are analyzed and reviewed,as well as the index calculation,forecasting accident selection and control measures. The achievements of all study stages are concluded. Considering the problems not solved,the research direction for analysis model, analysis method and control measures are pointed out.