Research On Parallel Converters Of Megawatt-Level Permanent-Magnet Direct-Drive Wind Power Genertion System

With the development and progress of the society, energy has been concerned by more and more people, developing clean and sustainable utilization of energy is imminent. Wind resources are very rich in China and the application of wind power generation technology is relatively mature, therefore there will be good prospects to develop wind-power in our country in the future. This paper is about to introduce one of the wind power technology:Permanent-Mgnet Direct-Drive Wind Power Generation technology.Due to the power rating of the power electronics device, in direct driving power system adopts parallel back-to-back structure of the converters. This paper is mainly about to introduce the control method of motor side paralle systems and grid side parallel systems in permanent-mgnet direct-drive wind power generation system,and the control method of circulation in parallel systems.Firstly,the mathematical model of permanent magnet motor has been analyzed in parallel motor control system, based on the analysis flux observation method was raised. Flux observer can estimate angle accurately when the motor running in low speed,so it can avoid the bad performance of sliding-mode observer in low speed and inhibit the speed and the rotor position of valuation measure of chattering phenomena, the theory of magnetic flux observer has been simulated in Matlab, greatly improved the performance of motor control system. The motor parallel system structure and the motor control strategies was presented, and achieved motor unit power output.Secondly,this paper analyzed the mathematical model of grid parallel system in the stationary frame and the rotation,also analyzed the power control of the grid, finally realized the active power and reactive power decoupling control. Grid side paralleling system with motor paralleling system are basically the same,so the control of grid side paralleling system was analyzed too.Finally, this research is to focus on the circulation of parallel converter's principle and the control methods.The thesis analyzed the mathematical model of parallel system in the stationary frame and the rotation and got the circulation model, through the analysis of the mathematical model of circulation forward the control method of circulation,based on the analysis of the mathematical model of circulation we did simulation experiment,at last in direct driving platform parallel system experiment is carried out, verify the feasibility of the control method of circulation.