Advanced Continuation Power Flow And Bifurcation Theory And Its Applications On Static Voltage Stability Analysis

In recent years, some of the world's nations successively happened voltage collapse accident. The causes of the accident are different, but it undoubtedly has caused great economic losses and social disorder. Voltage stability studies increasingly attracted people more and more widely attention. Mechanism and index of the voltage stability, and strategy of preventing voltage collapse, and controlling of nearby voltage collapse points are the focus of research.The PV curve, a relation curve between node voltage and regional load, can be instructed to the level of regional load and the extent of the voltage collapse because of load growth. Continuation power flow can trace complete PV curve, it has greatly applications in power system static stability analysis. However, there are two problems with it. The first is how to determine the load growth mode and make it close to actual power system; the second is that calculation process is very time-consuming. This paper analyzes and discusses each link of continuation power flow method, and presents an improved continuation power flow based on fast decoupled method and an improved continuation power flow based on piecewise and linear load forecasting curve. Meanwhile this paper studies the impact of load growth direction and load characteristics on voltage stability analysis.Bifurcation theory thinks that there are two types of bifurcation points. The saddle node bifurcation correspond the operating point on which Jacobin matrix has a zero eigenvalue. The limit-induced bifurcation causes sudden disappearance of stable operation point due to a generator reaching its Q-limit. This paper studies two bifurcation points, and an improved method for identifying and calculation bifurcation points is presented. Bifurcation set, made up of bifurcation points, constitutes a stable parameter space which is voltage stability domain. Using bifurcation theory, this paper analyses the effect of OLTC on the voltage stability considering load characteristics.The static analysis method based on power flow equation, making critical point as the limit of voltage stability, has mature technology and is easy to give stable indicators. This paper analyses some stable indicators and effect of the limit-induced bifurcation, and studies control measures which are beneficial for voltage stability.The effectiveness of methods in this paper is testified by IEEE 14,30 and 118 buses test systems.