Research On Voltage Stability Of Wind Farm Connected To Power System

Wind power generation, as an important use pattern, is the maturest and also has the condition of large scale development. Because of the large scale development of wind resource, each single wind farm with large size, the share of wind power in the power grid is increasingly greater. The integrated large-scale wind farm changes load flow of power grid. The randomicity and intermittence of wind will lead to instability output power in wind turbine generator, the fluctuating of wind farm power output would produce the certain influence to voltage quality of power network. Therefore, study on the voltage stability effect of wind farm on network becomes an important issues to develop and design the wind farm. In this paper, voltage stability problems of wind farm connected on power grid is researched, and the main contents are as follow:First, the development and present situation of wind power at home and abroad is discussed, the characteristics and types of wind power is described, and some technical issues of the integrated wind farm are analyzed. Research on voltage stability problems of grid-connected wind farm is presented, and the main contents are as follow, first, the structure and working mechanism of induction generator(IG) and doubly-fed induction generator(DFIG) is analyzed. Wind speed, wind generators and wind farm are modeled. Wind generator model includes aerodynamic model, transferring structure model, pitch controller model. IG model and DFIG model are analyzed.Second, the method of load flow calculation including wind farm is demonstrated, and the modification scheme which is used to treat different wind farms node in power flow calculation. The continuation power flow technique of power grid containing wind power plants is confirmed combining with conventional method, provides a preparation for steady run of grid-connected wind power system.In the end, the IG and SVC models are established in PSCAD, the transient voltage stability of IG based wind turbine is analyzed during three phase short-circuit fault, and using reactive power compensation SVC to provide dynamic voltage support. To the problems of wind farm based on DFIG during fault, this paper puts forward a technique of using rotor side converter for improving the response of voltage. In addition, factors influencing voltage stability of grid-connected wind farm is studied in the aspects of steady state.