Research on Stall Control for Small-scale Direct-drive Wind Power System with PMSG&CSC
|School||Hefei University of Technology|
|Course||Power Electronics and Power Drives|
|Keywords||current source converter wind turbine stall control PMSG adjustableunloading resistance SVM-DTC|
Small direct-drive permanent magnet synchronous wind power generationsystem has been widely used in the distributed micro-grid system; stall control isthe key technology of reliable operation for wind generation system. At present, theresearch on stall control for small wind generation system is still relatively less athome and abroad. So, this paper focuses on stall control for small-scale wind powersystem with PMSG and CSC to conduct related research, the concrete content is asfollows:Firstly, the topology and basic principle of direct-drive wind generationsystem with CSC has been analyzed. According to the system model, themathematic models of wind turbine and PMSG are established, respectively, andalso do some analysis and discussion about the method and principle of the CSCspace vector modulation (SVM). Which establishes the theoretical foundation andbasis to the proposed of new algorithms for wind turbine stall and PMSG control.Secondly, a new wind turbine stall control method and topology are proposedbased on the analysis of various wind turbine stall control methods. Above the ratedwind speed, make the wind turbine work in the stall zone so that the unit constantpower operation. And it can also dynamic absorb the over-power through thestepless speed regulation for unloading resistance, and, it can smooth go down byadjustable unloading resistance to prevent system failure by caused with overloadin out-speed.Meanwhile, for the traditional direct torque control (DTC) has comparativelylarge steady-error of rotor speed and torque, and higher voltage and currentharmonic component. And the rotor flux oriented control is difficultly to achieveunity power factor control on machine side and has some troubles with complexparameters. To solve these problems, stator flux oriented SVM-DTC method hasbeen presented in this paper, which not only achieve unity power factor control onmotor side, but also the steady-error of rotor speed and torque has been reduced andimprove the system dynamic-state and steady-state performances effectively.A unified control algorithm is adopted according to the proposed wind turbinestall control method, this method not only can achieve the MPPT mode of low windspeed area, also can realize constant speed and constant power operation mode in high speed area.At last, the simulation and experiment platform are constructed to verifyproposed new control methods. Simulation and experiment results have verified thecorrectness and effectiveness of the proposed new wind turbine stall control methodand stator flux oriented SVM-DTC method.