Research on fixed-pitch wind turbine running in deep stall region

The fixed-pitch wind turbines have simple structure and lower cost, which change the output power mainly depending on the stall characteristics of the blades when the speeds of the turbine is constant. To increase the output power of the turbines, the variable speeds running in deep stall regime should be researched. Fixed-pitch variable speed wind turbines can be operated not only for MPPT in low wind speeds but also for constant power control in high wind speeds with the speed control system, thus the fixed-pitch wind turbines have the power characteristics as that of the pitch-controlled wind turbines. The robust PID controller is designed for speed control system. The further analysis shows that the speed control system with the PID controller designed has good robustness under different wind conditions. The fixed-pitch variable speed wind turbine can be operated stably in operating wind speeds and the speed controller has good dynamic characteristics, which indicate that the fixed-pitch variable speed wind turbine can be operated not only for MPPT in low wind speeds but also for constant power control in high wind speeds.