Comparisons of Damping Controllers for Stability Enhancement of an Offshore Wind Farm Fed to an OMIB System Through an LCC-HVDC Link

This paper presents an effective control scheme to simultaneously perform power-fluctuation mitigation and damping improvement of a permanent-magnet synchronous generator (PMSG)-based offshore wind farm (OWF) fed to a one-machine infinite-bus (OMIB) system using a high-voltage direct-current (HVDC) link based on line-commutated converter (LCC). The rectifier current regulator (RCR) and the inverter current regulator (ICR) of the HVDC link are individually designed using modal control theory to render adequate damping to the dominant modes of the synchronous generator (SG) of the studied OMIB system under different operating conditions. A frequency-domain scheme based on eigenvalue analysis and a time-domain method based on nonlinear model simulations are both carried out to compare the damping characteristics of the two damping controllers. It can be concluded from the simulation results that the proposed LCC-HVDC link combined with the designed ICR can render better damping performance to the qualities of the LCC-HVDC and the OWF than the designed RCR.