An improved maximum power point tracking method based on decreasing torque gain for large scale wind turbines at low wind sites

 With the rapid development of wind power in China, high wind sites have become scarce and are often located far away from major load centers. Due to technological improvement and close proximity to load centers, low wind sites (wind speeds around 3–7 m/s) have become economically viable in China. However, the characteristics of low mean wind speed and high turbulence intensity at low wind sites make maximum power point tracking (MPPT) control challenging. Therefore, an improved maximum power point tracking (IMPPT) control approach is proposed in this paper. This approach is based on decreasing torque gain (DTG) control algorithm, and is designed to dynamically adjust the gain coefficient aimed for better energy capture at low wind sites. The proposed IMPPT algorithm is compared with traditional MPPT algorithms by simulation using actual wind speeds, including DTG control, adaptive torque gain (ATG) control, the improved MPPT control based on the reduction of tracking range (RTR-MPPT control), and an improved ATG control based on curve fit method (CFATG control). Simulation results verify that the proposed approach (IMPPT algorithm) is more effective.