Studies On The Modeling And Control System Of Direct-Drive Permanent Magnet Synchronous Generator Based Wind Turbine

Direct-Drive permanent magnet synchronous generator based wind turbines possesses remarkable technical merit, its research and development have received more and more attention and has a very good prospects. This thesis has studied on the modeling, control strategy and operating characteristics of the direct-drive permanent magnet synchronous generator based wind turbine. The main content of this thesis are as follows:(1) The paper derives the dynamic model of the permanent magnet synchronous generator expressed in the reference reamer rotating in synchronous speed; the aerodynamic model, shaft system model and full power converter model of the wind turbines models are presented.(2) Based on decoupling control principle, the control system of the direct-drive permanent magnet synchronous generator is designed, including generator side converter controller, grid side converter controller and rotor controller. Simulation for the case verifies the validity of the model and the feasibility of the control strategies.(3) The mechanism of voltage stability due to wind farm integration is analyzed. The stead-state voltage stability in the direct-drive permanent magnet synchronous generator based wind farm is analyzed using P-V curve method.(4) The transient voltage stability of direct-drive permanent magnet synchronous generator based wind turbine studied; The proposed transient voltage control strategy of grid side converter and DC voltage coupling control system can enhance transient voltage stability.(5) The fault current contribution of the induction generator, doubly fed induction generator and direct-drive permanent magnet synchronous generator based wind turbines are analyzed. The fault current contribution of the direct-drive permanent magnet synchronous generator based wind turbines in two different control modes is analyzed.