Research On Excitation Control For Grid-connected Wind Turbine

Energy plays an important role for the development of human society.Modern society and modern civilization can do nothing without the support of the energy.As in the history of industrialization in developed countries,China’s economic development requires a lot of energy as a guarantee.wind power generation is a new type of clean energy,which is safe and reliable,has low construction cost,clean pollution and large energy reserves.It is getting more and more people’s attention.Therefore,it is of great significance to research the wind power generation to make full use of wind energy,develop the industry with independent intellectual property,speed up the scale of wind power generation and promote rapid development of national economy.Wind power systems based on doubly fed induction generator（DFIG）are the most widely used in wind power industry.DFIG system is very susceptible to grid voltage harmonics and will affect the stable operation of wind power generation system.In this thesis,the variable speed constant frequency DFIG system is taken as the research object.Firstly,the current development status of wind power technology is introduced,and the harm of grid harmonics in the grid is expounded.In the second chapter,the 5^th and 7^th grid harmonic components which exist in the grid and the DFIG system have a negative impact on the maximum are introduced;The third chapter mainly introduces the operation principle analysis of DFIG wind power system,the use of control strategy,the computer modelling and simulation of the DFIG system and the verification of the model.The third chapter mainly introduces the operation principle of the analysis of doubly-fed wind power system,the use of the control strategy,the system of computer modelling and simulation and model validation work,based on the vector control strategy,establish doubly-fed wind power system simulation model,using the mathematical model for the computer simulation results compared with the measured data in test,the accuracy of the mathematical model is verified,provides the feasible research platform for the next chapter;The fourth chapter proposed innovative MRF and PR two kinds of harmonic suppression controllers,gives a detailed analysis and calculation of two kinds of controllers,using the simulation software of computer simulation is carried out harmonic controller,and has set up a experimental platform for the corresponding system for experimental verification,respectively for two kinds of harmonic suppression controller that triggered the harmonic component of the stator current before and after the operation result of the waveform acquisition and analysis,and analyses the experimental measured data from test and verification,verify the validity of the controllers designed in this thesis;the results of the MRF and the PR controllers are compared in Chapter 5,and the MRF controller is more effective in eliminating stator current harmonics,but with slower reaction times,while the PR controller requires less computation,but with better stability,the two controllers have the almost same effect to reduce the power grid distortion and torque oscillation.Finally,the future research focus of this thesis is further explored.