Analysis And Research On Voltage Stability Of Wind Power Accessing To The Regional Power Gird

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 follows:Firstly, 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 include aerodynamic model, transferring structure model, pitch controller model. IG model and DFIG model are analyzed.Secondly, several different methods used to analyzing static voltage stability of grid-connected wind power is described, for example,P-V curve method, V-Q curve method, sensitivity analysis method based on the conventional power flow calculation, each of them is described by their principles of analyzing voltage stability, provided a theoretical basis for researching wind farms running stably.Finally, adopting PSASP software for simulation analysis, calculates examples of the EPRI-36node system and Dongying, Binzhou power grid instance of wind power. The results of EPRI-36node system indicates that wind power has clear effects on voltage stability. In wind power system of a stable operation condition, after wind farms cutting out, the system node voltage will have varying degrees of decline. And the wind speed is higher, the effect is more obvious, U-Q sensitivity is higher, the voltage stability is lower. The results of Shandong power grid show:in a stable operating condition, wind power system can improve the voltage level, and has a supporting role on the voltage of distribution network, has certain improving effects on the safety and stable operation of power grids.