Study Of Power System Voltage Stability Based On Dynamic Analysis Method

Since the late 1970's, many power system voltage collapse incidents have happened around the world, which not only resulted in huge economic losses but also caused great social disorder. This prompted the long-neglected issue of voltage stability become a focus of attention and research in resent years. Power system is essentially a nonlinear dynamic system, generator and its excitation system, on load tap changer, reactive power compensation device and so on all have a great impact on it. The reliability of the results of voltage stability reaserch relate to power system component models and analysis methods. As a result, we focus on the dynamic analysis method and the effect of some key equipment on voltage stability. The results are summarized as follows:1) The models of some main components and dynamic analysis method used in voltage stability research are discussed. A new time domain simulation method (Union Time Domain Simulation Method, UTDSM) for dynamic voltage suability, which remedies the defect of transfer errors in segmentation method and can provide satisfied calculation accuracy and speed, is proposed.2) The effect of generator and its excitation system on voltage stability is investigated. Firstly, the change of voltage stability domain after the generator reactive power arrives at its limit is analysised.Secondly, we use a more detailed dynamic component model to study the impact of generator and its excitation system parameters on voltage stability. Finally, the effect of excitation regulator output limit is studied. Tracking equilibrium solution manifold, time domain simulation, one-parameter bifurcation analysis and two-parameter bifurcation analysis are included.3) The effect of on load tap changer on voltage stability is researched. As for the typical static load model, we study the factors which affect the critical point of on load tap changer's negative regulator effect, and the effect of different static load characteristics and change ways. We use a much more detailed induction motor load model to study the impact of its parameters on regulating effect of on load tap changer. Finally, we explore the effect of the dynamic characteristics of on load tap changer on voltage stability.4) The effect of reactive power compensation on voltage stability is studied. Based on an equivalent power system, the mechanism of reactive power compensation is discussed. The determination method of weak node in power systems is studied, and also the effect of reactive power compensation in different nodes. We research the static var compensator in detail, using bifurcation theory and time domain simulation method to analyze the impact of the time constant and magnification on voltage stability.