Stability enhancement of DFIG-based offshore wind farm fed to a multi-machine system using a STATCOM

In this paper, the simulation results of using a static synchronous compensator (STATCOM) to achieve damping improvement of an offshore wind farm (OWF) fed to a multi-machine system is presented. The operating performance of the studied OWF is simulated by an equivalent aggregated doubly-fed induction generator (DFIG) driven by an equivalent aggregated wind turbine (WT) through an equivalent gearbox. A PID damping controller and a hybrid PID plus fuzzy logic controller (FLC) of the proposed STATCOM are designed to contribute adequate damping characteristics to the dominant modes of the studied system under various operating conditions. A frequency-domain approach based on a linearized system model using root-loci technique and a time-domain scheme based on a nonlinear system model subject to a three-phase short-circuit fault at the connected bus are systematically performed to examine the effectiveness of the proposed control schemes. It can be concluded from the comparative simulated results that the proposed STATCOM joined with the designed hybrid PID plus FLC is shown to be superior for improving the stability of the studied system subject to a severe disturbance than the PID controller.