Wind Turbine Design And Wind Farm Performance Research Based On DC Grid-Connected

With the rapid construction of wind farms,more and more attention has been paid to the economical and effective ways of wind energy convergence and transmission.Traditional AC fans need to go through AC/DC-electrolytic capacitor-DC/AC process for power conversion,and need to adopt a huge and bulky power-frequency transformer boost structure.Because of its many conversion stages and high commutation loss,it is not conducive to the construction of small or decentralized wind farms.Therefore,the advanced DC converter and DC fan are studied.The internal conversion series of DC fan is less,the output of the unit is DC,and the DC units are connected to each other to form a DC wind farm.In this thesis,the grid-connected system of DC wind turbine and DC wind farm is analyzed and studied from the following aspects:Firstly,the development status and grid-connected mode of wind farm are analyzed and summarized.The working principle,basic structure,technical characteristics and application scope of DC fan and DC wind farm are discussed in detail.The topology structure of reduced matrix converter and bipolar voltage space vector modulation strategy involved in DC fan are analyzed in detail.Secondly,the mathematical models of wind turbines,permanent magnet synchronous generators,side rectifiers and grid-side inverters in the grid-connected system of DC wind farms are established,and the coordinated control strategies of the machine-side and grid-side of full power converters are proposed.Finally,the simulation grid-connected model of the system is established on the platform of MATLAB/Simulink,and the modulation effect of the converter on the machine side,the maximum wind energy tracking ability of the group when the wind speed changes,and the stability of the system when the grid voltage drops are simulated and analyzed.The results show that the bipolar voltage space vector modulation strategy can make the output of the reduced matrix converter to high frequency pulsed electricity,which meets the modulation requirements of the DC fan converter;the DC fan can achieve maximum wind energy tracking when the wind speed changes,and the system can quickly restore stability when the grid voltage drops,and decouple the active and reactive power,which confirms the coordinated control strategy.Slightly effective.In the future,the DC wind turbine and the DC wind farm will become the ideal scheme of wind energy convergence.This scheme reduces the commutation process,and the simulation results show that the DC wind farm has better performance and has certain practical application value.