| Compared with the wind power generation system based on DFIG, the wind power generation system based on PMSG eliminates the gearbox, so it has more advantages and will be more widely used, especially in the system with a small capacity. In this paper, the basic principles of permanent- magnetic direct-drive wind power generation system were introduced. The topology and characteristics of the three-phase grid-connected inverter were analyzed. Its mathematical models in a variety of topologies were given. Several kinds of control strategy of grid-connected inverter were analyzed and compared, leading to the double-closed-loop control strategy which is traditional but more practical in our research focus. The theory of MPPT and the relationship between DC-voltage and rotated speed of the PMSG were discussed. The best power curve of PMSG based on DC voltage -maximum output power was reached. The realization of MPPT on double-closed-loop control strategy was explained in detail. According to the principle of control strategy, the simulation model of the permanent-magnetic direct-drive wind power generation system was built in the Matlab environment. The simulation results showed that when the wind speed changed, the grid-connected inverter could inject the stable and reliable AC power into the power grid. Both the steady-state and transient performance were very good. Furthermore, a 5kW grid-connected inverter used for permanent-magnetic direct-drive wind power generation was designed to meet the need of the experiment. The hardware structure used TMS320F2407 as control core, and equipped with several kinds of peripheral circuits. Software module is used to realize the control algorithm, and integrated a variety of protection logic. Finally, a 5kW experiment platform was set up. Network and sine wave current output experiments were conducted. Experimental results show the effectiveness of the hardware and the accuracy and robustness control strategy.
|
PDF Full Text Request