A Study On Visualization Of Static Voltage Stability Region In Power Systems

Since 1980s, with the continuous enlarging of power systems, voltage stability has been one of the most serious problems threatening the security of power system operation. To guarantee the voltage stability of the systems researchers expected to get some help from monitoring some indices, which reflect the voltage stability. However such indices do not have linear relations with the operating parameters, it is hard to forecast the voltage stability margin by these indices. Unlike the indices, static voltage stability region (SVSR) can give monitors global information of the feasible operating region and help them determine the voltage stability of the system directly and quickly.So far, the existing voltage stability visualization methods still depend on the large amount of simulation, which will cost a long time to find the SVSR boundary. This paper presents two methods for the visualization of SVSR both in the active power generation injection space and in cut-set space. In generation injection space a hyper plane equation is presented, which can quickly calculate the hyper plane that is tangent to the SVSR boundary at a certain point. And this hyper plane is used to estimate a considered part of the SVSR boundary. For visualization, a sensitive generator selection method is also developed to reduce the high dimension of generation space. As for cut-set space, a fast and practical approach is also developed to estimate part of the SVSR boundary. Here linear equations are derived to estimate part of the SVSR boundary in state space. With these equations, part of the SVSR boundary is calculated in state space very quickly. And then this part is mapped into cut-set space by power flow equations. The low dimension of cut-set space is really suitable for the visualization of SVSR and such space is also fit for the custom of voltage stability monitoring and control.With this paper's methods, part of the SVSR boundary can be calculated and visualized both in generation injection space and cut-set space, and the fast speed indicates the practical value of the methods in on-line SVSR calculation and visualization.