A Study On The Operating Characteristics And Impact On Electric Power Network Of Asynchronous Wind Power Generation

With the increasing severity of energy and environment problems, Wind energy, which is clean, abundant, low cost and mature in technology, has became the fastest developing new energy power generation technology. As an important part of whether a region has ability to develop wind power, wind resource assessment provides the basis for the wind farm micro-site and economic evaluation. So, it is necessary to do study on wind rescource assessment. At the same time, the power output of a wind generator is fluctuant, which is determined by the instability and intermittence of wind speed, so output fluctuation and other factors will cause changes in voltage stability of grid and wind generator. There are a lot of nonlinear converter devices in wind power generation system, so with the transmission of active power to the grid, wind generator will alse affect the power quality. Therefore, study on operation characteristic of wind generator and impact after wind generator accessing to the grid is meaningful. The major study and contributions are as follows:In the first of part of this thesis, wind resource assessment has been studied and three kinds of Weibull parameter estimation methods has been introduced. After comparison of three methods and traditional method with the data of the weather station in Zhangbei, it is proved that Maximum likelihood estimation method has greater accuracy in the calculation of wind power characteristic index. Finally, the impact of Weibull parameter in economy is analyzed by expecting generating capacity and estimating net present value. The results show that Weibull parameter estimation plays an important role in economic assessment of wind farm.Secondly the mathematical module and wind speed module of wind generator have been established. Transient simulation of "fixed pitch induction generator" module and doubly fed induction generator have been achieved by using simulation tool PSCAD/EMTDC as a platform. This thesis introduces a lot of these tow type wind generator including the way of access grid, operating condition, transient characteristic causing by wind speed change and three-phase short circuit. The future development trend of wind generator has been revealed by analyzing the operating characteristic of these two module.Thirdly, this thesis also analyzes the voltage fluctuations to the wind farm and transmission lines caused by the changes of wind speed and line parameters, load access or not, whether the dynamic reactive power compensation and so on, when one small 10MW wind farm of"fixed pitch induction generator" module wind generator connects to the grid.Finally, the harmonic principles caused by doubly fed induction generator connected to the grid was analyzed, which shows that the harmonic pollution mainly derives from doubly fed induction generator, and takes huilai guanshan wind farm of GuangDong Province as an example to evaluate the power quality of this wind farm according to the national standard of harmonic voltage distortion limits, the total harmonic voltage distortion, harmonic current limits and so on.