Nonlinear Pitch and Torque Controller Design for Wind Turbine Generator Using Lyapunov Function

Key Words: Lyapunov Stability Theory(리아프노프안정성이론), Wind Turbine Modeling(풍력발전기모델링), Blade Pitch Control(블레이드피치제어), Generator Torque Control(발전기토크제어),Nonlinear Simulation(비선형시뮬레이션)초록: 본논문에서는풍력발전기의회전속도와출력을제어하기위한블레이드피치제어기및발전기토크제어기법을제시하고비선형시뮬레이션을통하여그성능을확인하였다. 회전속도오차및출력오차를이용한양한정함수를정의하고리아프노프안정성이론을적용하여정적피치제어기와동적토크제어기를설계하고, 제어기설계모델과실제적용모델간의차이를보상할수있도록시뮬레이션기반최적화를이용하여설계인자값을결정하였다. 풍력발전기제어기설계에가장많이사용되는동력전달계모델을기반으로제어기설계절차를예시하였고, 대표적으로사용되는비례-적분-미분제어및최대출력점추종토크제어기와성능비교를통하여제안된제어설계기법의타당성을검증하였다.Abstract: In this study, a method for designing blade pitch and generator torque controllers for a windturbine generator is presented. This method consists of two steps. First, the Lyapunov stability theory is usedto obtain nonlinear control laws that can regulate the rotor speed and the power output at all operatingranges. The blade pitch controller is chosen such that it always decreases a positive definite function thatrepresents the error in rotor speed control. Similarly, the generator torque controller always decreases apositive definite function that reflects the error in power output control. Then, the simulation-basedoptimization technique is used to tune the design parameters. The controller design procedure and simulationresults are presented using the widely adopted two-mass model of the wind turbine.