Research On Finite Control Strategy Of Large Scale Wind Farm Power Ramping Under High-Low Wind Speed

With the rapid development of the global economy,the demand for electricity and the requirement for energy saving and emission reduction are increasing day by day.Many countries pay more and more attention to wind power as one of the most commercial renewable energy sources.Wind power ramping as a typical event of wind power uncertainty and fluctuation has great influence on the stability of power grid.In this thesis,the power ramping event of large scale wind farm is taken as the object of study,and the optimal control strategy of power ramping of large scale wind farm.The main research work is as follows:The basic theory of wind power generator technology is briefly introduced.The mathematical model of doubly fed induction wind turbine and the mathematical model of wind farm are built.A control strategy of power ramping optimization for wind farms at low wind speed without wind turbine cut-out is proposed.By using the non-dominated sort genetic algorithm with the elite strategy,the wind power ramping curve is optimized,and the optimizing curve as the reference curve give consideration to the rate of ramping and the abandon air volume.The output power curve of the wind farm is tracked by the feedback control method based on DFIG converter control and variable pitch angle control.In the MATLAB / Simulink environment,the calculation and analysis of the simulation examples are carried out to verify the effectiveness and superiority of the power ramping control strategy of the wind power ramping under low wind speed.A control strategy of power ramping optimization for wind farms at high wind speed including wind turbine cut-out is proposed.By using thenon-dominated sort genetic algorithm with the elite strategy,the power ramping curve is optimized and it as the reference curve of the cutting process.According to the different wind speed characteristics and failure rate of each unit in the wind farm,the pre-cutting priority factor is proposed at the first time,the factor determine the cut-out priority and the cut-out time nodes for each turbines.Wind turbines cut-out based on this factor and make output power curve track the reference curve to reduce the power fluctuation caused by the wind turbine cut-out at high wind speed.A semi-physical simulation system is built by using the real time digital simulator platform and DSP physical controller,and a semi-physical experiment is carried out.The experimental results verify the superiority and effectiveness of the control strategy proposed.