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The impact of model predictive control and supplementary aerodynamic actuators on extreme load mitigation of wind turbines

 
: Anstock, F.

Aachen, 2017, XIII, 97 S.
Aachen, Univ., Master Thesis, 2017
Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit BMU
41V6793; ELBA Phase1
Regellungssysteme zur Extremlastbegrenzung für große Windenergieanlagen - Phase 1
Englisch
Master Thesis
Fraunhofer IWES ()
wind energy; Model Predictive Control (MPC); extreme load; aerodynamic actuator

Abstract
This thesis examines the impact of an additional pitch actuator near the blade tip on extreme load reduction of the Fraunhofer IWES 7.5MW wind turbine during full-load power production. To control the generator torque as well as inner and outer pitch systems simultaneously, a time-discrete 38-state linear 10 Hz model predictive controller (MPC) is designed. The corresponding state-space model is continuously updated to the current turbine state by four-dimensional interpolation among a set of priorly linearised models. As a first approach, perfect system observability is assumed. Evaluation simulations were performed with a normal turbulence model and a 50-year extreme operating gust during normal power production, specified in the German Lloyd certification guidelines. The subsequent comparison includes four MPC versions with and without a second pitch and a 5 s long wind forecast, respectively, that are benchmarked to the reference turbine’s baseline PID-controller. The results show extreme load reductions of up to 56% for the tower base fore-aft moment and up to 75% for the blade flapwise moment as well as significantly reduced turbine motions for the MPCs compared to the baseline controller that is not equipped with a second pitch system.

: http://publica.fraunhofer.de/dokumente/N-473917.html