Research On Doubly-fed Inductive Wind Generators Connected With Grid Stability

Energy and environment are pressing problems that must be settled by human beings for future survival and development.Wind power has preferable economic and social benefits because of its cleanliness and free pollution,short construction period,flexible investment and few occupation of land. At present, there are big gaps between china and developed countries in wind turbine's theory and application research.Variable-speed constant frequency wind power technology has become one of the main technology in wind power technology. With the development of wind power technology,the capacity of wind generator is growing,and the impact which connect with the net can not be ignored, therefore,it is an important issue that research on the impact of wind generator connected with power systems which should be solved urgently.This paper is based on the theory and practice, it has studied the grid-connected stability of variable speed constant frequency double-fed induction generator.The development and status of wind power at home and abroad are analyzed in this paper at first,it has described the basic structure of variable speed constant frequency doubly-fed wind power system.This paper analyzes double-fed induction generator operation theory, conducts a theoretical derivation of double-fed generator's mathematical model by coordinate transformation,it builds the mathematic model of variable speed constant frequency doubly-fed wind power generator on the dq synchronous rotation coordinate and builds other parts of the mathematical model of wind power generation system. Through the established mathematical model, it has built grid-connected simulation model of system by Matlab/Simulink.simulated the disturbance by the wind speed and system fault when the double-fed wind generator on the grid. The simulation results show that double-fed wind power system can use of wind energy effectively, ensure the stability of the grid voltage when disturbed by wind speed and the whole system can stable running; When line fault occurs, the double-fed wind generator have a capacity of reactive power regulation, can properly control so that ensure system stability.The research show that the double-fed wind generator have good dynamic stability when grid-connected, it can make the appropriate regulation to ensure the stability of system,and laid the foundation for further study of variable speed constant frequency wind power grid-connected.