Research On Control Strategy And Hardware Implementation Of PMSG

In recent years,with the wind power incorporated into power system in large -scale, wind turbines brokefrequently away from power system because of the lack of LVRT ability. As one of the mainstream model ofvariable-speed constant-frequency wind power generation system, permanent magnet direct-drive wind turbines have been widely used. Therefore, the permanent magnet direct drive synchronous wind power generation system is the research object of this paper.The study on the control strategy of symmetric and asymmetric LVRT converter of PMSG system has been carried out deeply.Meanwhile,in order to make the effect of experiment more close to transient controleffect,universal protection control platformis established to validate related experiments.In this paper, theoretical research and hardware testing on fault transient characteristics of permanent magnet direct-drive wind power have been launched as follows:The steady-state mathematical model of permanent magnet wind generator is discussed, and then related research of PSMG power system transient fault characteristics have been studied on the base of the steady-state control. Considering transient characteristicsof symmetrical fault,coordination controlof Chooper circuit and network-side control strategy change is proposed.Based on steady state control model of PSCAD, Simulation have been performed to verificatethe control strategy of symmetrical fault. For asymmetric fault, positive and negative sequence voltage directional control strategy considering asymmetric voltage drop has been proposed.This control strategyeliminate two harmonic components in the DC bus.Transient process can not be completely simulated just relying on simulation results in the study of fault transient characteristics of wind power.Therefore, universal protection control platform has been established and thenthe closed loop test system containing hardware platform and RTDS has formed in the basis of theoretical research. Based on this test system,the research on symmetrical and asymmetrical low voltage through control strategy has also been carried out.Finally the feasibility of the control strategy is validated by the test results.