Study On Voltage Stability Of Power System With Wind Power Based On Bifurcation Theory

Due to the randomness and intermittent of wind power, it can affect systemvoltage stability with large-scale connecting grid. In this thesis, the problems ofvoltage stability in power system with wind power were studied by bifurcationtheory, AUTO07was used as the general bifurcation analysis software. The workswere mainly carried out as follows: study the bifurcation theory and summary theskills of using AUTO07analysis software; deeply study the impact of its operationmode, stator and rotor parameters on the system dynamic voltage stability, especiallythe significant influence of doubly-fed induction generator (DFIG) on the systemdynamic voltage stability; study the influences of magnification and referencevoltage value on system voltage stability, which consider the effect of equivalentsynchronous generator Auto Voltage Regulator (AVR) and reactive powercompensation device Static Var Compensator (SVC). By the research, sometheoretical and practical conclusions were summarized as follows.In this thesis, a typical three-node power system model consisting of windpower generation, load and network was firstly established and taken to study theinfluences of DFIG operation mode, stator and rotor parameters on the voltagestability of power system, which applies AUTO07software. The results show thatwind speed can affect the wind power output, therefore lead to the changing of loadnode voltage. As wind speed increases, the system stability region between loadnode voltage and reactive power becomes smaller gradually, and node voltage dropmonotonously in the saddle-node bifurcation point. When wind speed reaches at12m/s, Hopf bifurcation has occurred before the emergence of saddle-nodebifurcation point and ordinary static bifurcation point, when the low frequencyoscillation phenomenon of load node voltage appears. The Hopf bifurcationboundaries of system appear obvious difference when DFIG stator and rotorparameters changing, and the system stability region increases or decreases. At the same time, the influences of magnification and reference voltage of AVRand SVC on system voltage stability was studied in this thesis. Wind farm wassimulated by dynamic load model and the equivalent synchronous generator wassimulated by a three-order simple model. AUTO07was used to analysis theexamples, the results showed that the addition of magnification and referencevoltage can effectively improve the system ability of accepting wind power injection,thus contribute to the maintenance of system voltage stability. Moreover, increasingmagnification of AVR and SVC to improve voltage stability have the similar results,while increasing reference voltage of SVC can be move conducive to system voltagestability than AVR.