Influence of control methods on torque oscillations in wind energy converters

Stochastically fluctuating wind energy density has major influence on wind energy converters performance. Dynamic power flow variations in the power drain of wind energy converters lead, among others, to dynamical torque changes. Through the power drain, the load peaks are fed forward to the electrical grid and cause early damage of mechanical components, thermal overload of electrical components, as well as voltage variations on the electrical grid. In this paper the influence of control methods on the cumulated load in the wind energy converter's drive train is analyzed. The control methods considered in this paper are optimal rotational speed control, linear power average control, self searching optimum and stochastic dynamic optimization. Conventional control approaches, optimal speed, linear power average, and self searching optimum lead to high shares of critical drive train torque. The stochastic dynamic optimization control significantly reduces the occurrence of unfavorably high torque values.