Control strategy of DFIG main control system during low voltage ride through

The pitch control of 1.5 MW 82 m doubly-fed wind turbine is analyzed and the torque factors are calculated based on GH BLADE software for 0°~20° pitch angle and 3~14.7 tip speed ratio. The drive chain load and maximum adjustable blade angle during LVRT( Low Voltage Ride Through) are analyzed. The pitch control strategy and the active power recovery strategy based on EFC and normal pitch angle command when wind turbine enters into LVRT are proposed for different wind speeds. The simulative calculation indicates that, the aerodynamic torque can be reduced by adjusting the pitch angle for realizing the smooth transition of wind turbine velocity during LVRT and the coordinative operations of pitch angle callback and fast active power setting can reduce the power oscillation at the end of LVRT. The lab test on 110 kW test-bed and the site test of 1.5 MW doubly-fed wind turbine unit show that, the proposed control strategy realizes the control of velocity and power recovery during LVRT under different wind conditions.