A yaw control Approach using economic aspects

Kurzfassung

The share of wind energy in modern societies energy supply increases constantly. Whereas blade pitch and torque control of wind turbines are extensively covered within literature, yaw control is rarely discussed. Yaw is controlled in order to increase the turbines energy output, yet turning a heavy nacelle with a large rotor into the wind also consumes significant amounts of energy. Furthermore, there is the desire to reduce wear in gears, bearings, and brakes. To make matters worse, the sensitivity of the turbine’s power generation on the yaw angle depends on the overall wind velocity in a non-linear way. Practical problems like sensor noise and the avoidance of cable twist occur as well. Therefore, we developed an energy optimized control scheme based on a dead-band controller with hysteresis and an integrated positioning feed forward algorithm. For the control design, the DLR EWITAC Library was used that enables the object-oriented modelling and simulation of wind-turbines based on the Modelica standard. The controller was designed using simplified models and validated with the computer simulation of a fully flexible wind turbine combined with a stochastic wind model.