Research On Voltage Stability Of Power Systems Based On Bifurcation Theory

With the rapid development of electric power system in China,the power gridstructure is becoming more complex and tending to the development of high voltage,large power grid and remote.It is more easily lead to voltage collapse accident.Thesystem stability especially voltage stability problem becomes more and moreimportant.In recent years, the problem becomes more complex with the dynamiccompensator used.Combining the bifurcation theory and numerical simulationmethod,a mathematical model of power system voltage stability is derived at theproblem of power system voltage collapse.The instability model of power systemvoltage and bifurcation boundary is analysed with the MATCONT bifurcationsoftware.Installation of dynamic compensator is proposed in weak point to improvethe voltage stability of power system.The preventive and corrective measures basedon dynamic compensator are studied.The main research contents include:Firstly,to summarize the research status of voltage stability in powersystem.Based on analyzing the basic principle of bifurcation theory,the analysismethod of power system voltage static and dynamic stability is studied.Themathematical models of power system voltage stability derived lays the theoreticalfoundation for analysis of voltage collapse in following chapters.Secondly, the comprehensive tangent and secant method, the method of trackingthe equilibrium solution manifold is improved by using bifurcation softwareMATCONT.Based on the judgement on the basis of all kinds of bifurcation,the saddlenode bifurcation point and hopf bifurcation point are calculated.The influence ofpower system voltage to two bifurcation points and the corresponding Instabilitymodel are analysed.The bifurcation boundarys in the saddle node bifurcation pointand Hopf bifurcation point based on the double parameters are studied. Finally,installation of dynamic compensator is proposed in weak point toimprove the voltage stability of power system.Its application in the dynamiccompensator of TCR-FC SVC is studied and a mathematical model on power systemvoltage stability is derived. According to the load sensitivity index of static stabilitymargin,the weak point of the system is analysed and the dynamic compensator isinstalled.Study on the saddle node bifurcation point is delayed effectively after theinstallation of dynamic compensator.The reference voltage Vrefand magnificationfactor KSVCon dynamic compensator effects of static and dynamic bifurcationphenomenon is discussed.Study on the system dynamic stability is improved after theinstallation of SVC additional control.Simulative experiments are conducted to verifythe feasibility and effectiveness of method.