Research On Control Strategy Of Direct Drive Permanent Magnet Synchronous Wind Power System

Direct-drive permanent magnet synchronous wind power system with its non-gear box,low failure rate,high efficiency and high reliability in modern wind power generation system occupies an important position,and the system’s control strategy will be the system power generation and grid Have a direct impact.This paper mainly focuses on the problem of voltage regulation in the direct drive type permanent magnet wind power system and the problem of LVRT.The main contents are as follows:Firstly,the research background and significance of wind power generation are introduced.The main fan types in modern wind power generation system are briefly analyzed.The research status of direct control type wind power system control strategy is analyzed.Third,the working principle of wind turbine,permanent magnet synchronous motor,power converter is explained.The mathematical model of the power converter and the synchronous motor is established by using the space vector method,and the coordinate transformation of Clarke,dq,and abc-dq are analyzed in three forms.In this paper,the principle of the grid side converter in the four quadrant is analyzed,and the AC voltage and current vector is given.Fourth,Grid criterion requires that the wind power generating system should have PCC voltage regulation ability.Based on this problem,the reactive power support strategy is proposed for direct drive permanent magnet synchronous wind power generation system in paper.The mathematical model of wind turbine,permanent magnet synchronous motor and voltage source converter is established,the control principle of the grid side and the machine side converter are analyzed,and the control graphs also are given.The simulation model of 1.5MW direct drive permanent magnet synchronous wind power generation system is established by Matlab/Simulink simulation software.Simulation results show that the proposed control strategy can improve the PCC voltage on the basis of DC bus voltage stability.When the proposed control strategy is applied for multiple wind turbine generators in the wind farm,it can restore the PCC voltage to the normal range.At last,Grid criterion requires that when a fault occurs or disturbance and node voltage sags,wind turbines should have low voltage ride through ability.Based on this problem,the low voltage ride through strategy is proposed for super capacitor storage system with direct drive permanent magnet synchronous motor in paper.The grid side,machine side and energy storage system for the design of the control strategy,and the control graphs also are given.And compared with the traditional control strategy and the control strategy with Crowbar circuit.In Matlab/Simulink simulation platform is set up based ob super-capacitor energy storage device of 1.5MW direct-drive permanent magnet synchronous wind power system simulation model.The simulation results show the effectiveness of the proposed control strategy.