| In today’s world,energy supply is becoming increasingly tight.Insufficient energy supply and serious environmental pollution are the main factors restricting the economic development of all countries in the world.On the road of transition to a sustainable development and environment-friendly society,all countries are facing the huge challenge of developing renewable clean energy.Electricity production is the main way of energy consumption,and the research and application of renewable clean energy in electric power production is in the ascendant in countries all over the world.Among various renewable energy sources,wind energy has become the focus of research and application due to its advantages such as non-pollution,renewability,reserves abundance and widespread distribution.With the development of highperformance and high-quality permanent magnet materials and the development of high-power converter technology,direct-drive permanent magnet synchronous generators(D-PMSG)are gaining more and more attention in wind power generation Application and carrying out relevant research have important theoretical significance and practical value.This paper takes D-PMSG wind power generation system as the research object,and the main contents are as follows:This review summarizes the development status of wind power generation and the research status of wind power generation and its control technology.It is pointed out that due to the strong nonlinearity and time-varying nature of wind power,it is difficult for traditional control methods to achieve satisfactory results,and more advanced control methods must be adopted.The structure of the direct drive wind power generation system is introduced,and the mathematical model and the Simulation model of the D-PMSG wind power generation system including the wind turbine,D-PMSG,converter and its control system is established.D-PMSG wind power system converters include turbine-side converters and gridside converters.The machine-side converter adopts dual-loop vector control of outer loop speed and inner loop current.Since the generator-side converter directly faces the system impact caused by the time-varying wind speed,the controller is required to have efficient control performance,and the controller parameters are required to be adjusted online.The traditional PI controller adopts trial and error method or Ziegler-Nichols(ZN)method to determine parameters,which is inefficient and cannot realize online adjustment of PI parameters.For this reason,based on fuzzy control theory,this paper designs a fuzzy PI controller for the outer loop speed of the generator-side converter which can adjust PI parameters online.Aiming at the shortcomings of fuzzy control "after" control,the gray predictive control with the characteristics of "before" control is introduced,and the gray fuzzy PI controller is designed for the outer ring speed of the generator-side converter.The simulation results show that the gray fuzzy PI controller designed can better maintain the maximum wind energy utilization rate and complete the tracking of the maximum power point faster when the wind speed changes.The grid-side converter adopts dual-loop vector control of outer loop voltage and inner loop current.In order to improve the control performance,this paper combines the traditional PI control method with the gray predictive control method to design the gray predictive PI controller of the grid-side converter outer loop voltage.The simulation results show that the improved control method can better maintain the stability of the DC link bus voltage,and achieve the purpose of unit power factor grid connection more quickly.Due to the existence of the DC bus voltage,the random wind speed has relatively little disturbance to the grid side.The gray predictive PI control method can achieve excellent dynamic performance.Considering the complexity and economy of the control system,the grid-side converter only adopts the grey predictive PI control method. |
PDF Full Text Request