Toward controlled wind farm output: adjustable power filtering

This paper presents research into the limits on controllable power output from wind energy conversion systems. The viewpoint of imposing delivered power as a control input is explored though the introduction of a novel control structure for a fully-rated converter interfaced wind turbine. A singular perturbations decomposition of the system dynamics into two separate models underlies the new structure. A preliminary discussion of the stability implications for the turbine hub is offered, using torque-speed diagrams. Usefulness of the singular perturbation models and control structure is illustrated by its application in a power filtering methodology that specifies the delivered power as a filtered version of available wind power. Simulation results demonstrate the controlled system's ability to absorb wind power variations and completely isolate its torsional modes from the grid