Visualization And Application Of The Voltage Stability Regions Of Power Systems

Electrical power has become the foundation of the development of modern society. One of the important features of modern power systems is high-voltage and long-distance transmission. With the world-wide development of power market, the systems are more often operating near their stability limits and there is large probability of voltage instability. On the contrary there is a lack of powerful tools for voltage stability analysis. The traditional approaches for power system static voltage stability analysis are "of point-wise". Only few information can be given by this kind of methods. In this thesis, the "region-wise" approach is applied to voltage stability analysis and monitoring, which is a new methodology and can give operators the global index of system stability and security status. And some conclusions are derived:First, a software package on UNIX platform has been developed for power system voltage stability analysis and monitoring based on the static voltage stability region in cut-set space (CVSR), which can visualize the stability margin of specified interfaces as planes in 3-dimension and lines in 2-demension. This software has run on the EMS of Henan power system successfully for the first time.Second, base on the linear description of CVSR this thesis presents linear optimal models for the calculation of ATC and generation dispatching. By using the models the constrains of voltage stability and capacities limits of generators and transformers can be satisfied at the same time.In order to improve the efficiency of power system voltage stability analysis a new static equivalent method is presented including the selection of the correlation area using L index and the simplification of the remaining part using a modified Ward-type equivalent method.