Design and comparison of quasi continuous sliding mode control with feedback linearization for a large scale wind turbine with wind speed estimation

In this paper, dynamic modelling and control of WindPACT 1.5 MW wind turbine in Region 2 for extracting the maximum energy from wind is investigated (where the wind velocity is greater than 'cut in' and below 'rated' wind speeds). In this region, the generator torque must regulate the rotor speed in its optimal value while the blade pitch angle is considered constant in its optimal value. To achieve a more accurate model, wind turbine is modeled as an electromechanical system with two masses dynamics. A new method based on adaptive neuro fuzzy inference system (ANFIS) is considered for wind speed estimation; where rotor speed, output power and pitch angle are inputs of such system and estimated wind velocity is the output. Using estimated wind speed, two control methods based on feedback linearization & quasi continuous sliding mode control are designed for tracking the optimal rotor speed and increasing the efficiency. For implementation of feedback linearization approach, design of an observer based on high order sliding mode is investigated. Performance of these control methods is compared in terms of different mean wind speeds in Region 2. Results are validated by FAST which shows that feedback linearization control with observer has a better ability in performance and load reduction in various wind speeds.