Active Damping Control Strategies for WEC with VSM considering DC-Link Dynamics

Abstract

The rising share of wind energy conversion systems in the electric energy supply results in growing economical aspects of the assets’ size and maintenance costs as well as in challenges to maintain the stability and robustness of the utility grid. To fulfill requirements such as ancillary grid services, the virtual synchronous machine has been in the focus of research as grid-supporting or grid-forming control for grid-connected power electronic converters. Its application in WEC requires an adaption of the overall control structure compared to a conventional vector control, so that also the widely investigated active damping controls for mechanical torsional oscillations need to be analyzed for the adapted structure with a machine-side DC-voltage control. Therefore, in this paper methods to achieve active damping of torsional oscillations are designed with extended DC-voltage control. A special regard is put on the non-linearity of the intermediate circuit and the variable stator voltages of variable-speed WECs. Simulation results validate the effectiveness of the active damping controls and the stability of DC-link voltage control.