Research On Grid Connection Technology Of VSCF Wind Power Generation System

People on earth are wasting of the existing resources (coal, ore, water etc.). And we incorrectly treat the life garbage, industrial waste and many other factors, which force us to face with a shortage of resources and deterioration of the environment crisis of survival. And it forces people to try new energy development. Wind energy is a renewable energy. It is the fastest growing clean energy, and it has large-scale development and commercial development prospects. The rapid development of wind power generation technology and the wind power installed capacity embody the consensus and action of many nations. Wind scale application in twenty-first century will be an important symbol of the development of human society.However, to achieve this goal must first complete the transition of the wind from complementary energy to alternative energy sources, so that the utilization of the wind energy by remote areas without electricity to the conventional electrical area. This requires to develop grid-connected generation system with superior performance. In this context, this paper discusses research on grid connection technology of VSCF wind power generation system, and the details show as follows:This paper briefly introduces the basic concept of the technology and the direction of the wind power generation development, as well as the theory of the doubly-fed wind power generation system. Combining the achievements in scientific research, establish the double fed motor mathematical model under the two-phase synchronous rotating coordinate system. According to the control target of the rotor side and grid side converters, establish the converter model.In order to achieve shock less gird connection of the wind generator with high-capacity, by analyzing the operation behavior of variable speed constant frequency (VSCF) wind power generation based on doubly fed induction generator, the article presents double integral sliding mode control strategy based on the reference value of the current of the rotor. This control strategy has quickly dynamic response and strong robustness for grid voltage fluctuation and the variation of motor parameters. And this control strategy avoids the impact of grid cause by the stator flux linkage testing inaccurate. The results of the study show that this method in this paper is effective.Analysis the basic working principle, and put forward a kind of control method which is the combination of improved voltage control method and PI control method based on NN control to control the energy injected into the grid and reduce the harmonic components of the voltage and the current. And with the fast parallel processing capability and study capability, the computing time is reduced. Therefore the harmonic components caused by the delay of the control are reduced. And at the last build the simulation model in MATLAB/Simulink environment with the NN toolbox and do the simulation study in the variable speed constant frequency wind power system. The results prove that the new method is feasible.