Control of variable-speed variable-pitch wind turbine with doubly-fed induction generator under highly turbulent conditions

Highly turbulent wind condition such as wind gusts with speed change can lead to large loads on the turbine and unnecessary turbine shut-downs by the supervisory system due to rotor overspeeds. Wind turbine control during such winds is a very difficult task that often can´t be efficiently accomplished by classical wind turbine control system. This paper presents a novel approach of torque control intended for a variable-speed variable-pitch wind turbine with doubly-fed induction generator operation during strong and gusty winds. The approach relies on a combined use of generator electromagnetic torque and pitch control. Additionally, a ripple torque technique was adopted to increase the drive train damper to avoid gearbox vibration. From the GH-Bladed simulation results on different control schemes, the proposed approach is capable of preventing rotor overspeed and can also reduce the loads of drive train.