Model fidelity prerequisites for variable speed pitch-regulated wecs with state-feedback control

With increased structural flexibilities of modern wind energy conversion systems (WECSs), torsional oscillations can be hazardous to the drive train components as well as compromise output power quality. The proposed control paradigm is based on the linear quadratic Gaussian (LQG) to damp these undesired oscillations, and utilizes only one measurable feedback signal: generator speed deviation. An optimal state estimator provides a good estimation for the aerodynamic torque thereby determining the target trajectory to which the controlled system should converge. The objective is to optimize aerodynamic efficiency in low to medium winds, and add damping to the drive train at above-rated wind speeds. A pitch controller prevents rotor overspeed by ensuring the maximum power constraint is respected. The approach in control design involves detailed modeling of the various subsystems that make up the WECS.