Wind Turbulence-Induced Power Fluctuations Mitigation in PMSG-Based Wind Turbines By a Coordinated Control Scheme

Power fluctuations in large-scale wind turbines (WTs), induced by persistent wind turbulences, can degrade the reliability of power modules and increase mechanical stress on light-strength structural components. These issues entail intricate challenges for system operators in terms of operation and maintenance. This paper investigates specifications of power fluctuations in PMSG-based WTs and presents a control scheme advantageous both below and above the rated wind speed, without requiring additional energy storage devices. This work strives to bridge the gap between the complicated art of WT modeling and wind turbulence-induced power fluctuations aiming to reveal the origin of power fluctuations in terms of operating regions and control strategies. In the proposed control scheme, the power fluctuations are mitigated without any auxiliary control terms below the nominal wind speed. Above the nominal wind speed, the power smoothing action is performed via three items, in which the machine side converter (MSC) virtually regulates the rotor inertia, the grid side converter (GSC) exerts the damping component, and the pitch control system helps enhance the damping mechanism. The feedback gains of the auxiliary terms are optimized while considering their interactions. Simulation results illustrate that the proposed control scheme effectively mitigates both the electrical and mechanical oscillations.