Trend in Voltage Stability Problem and its Analysis Methods in Power Systems

Voltage stability problem has been studied for long time as an important subject for secure power system operations. Various methods have been developed so far in order to analyze the complicated phenomena to predict and avoid voltage collapse. Recently, the complexity of the problem is increasing due to considerable change in power system circumstance under deregulated environment, where new types of instabilities such as immediate instabilities tend to increase; requirements for analyses are also changing. This article presents recent trend in voltage stability studies and development of analysis methods.