Impact of DFIG based wind generation on grid voltage and frequency support

Recent trends indicate replacement of fossil fuel driven conventional synchronous generators from the existing power grid with inverter interfaced renewable energy sources in coming years. A significant portion of these renewable energy sources is predicted to include doubly fed induction generator (DFIG) based wind turbine. This will cause a significant change in the grid dynamics, due to reduced system inertia and the intermittent nature of wind power. The impact of grid integration of DFIG-bases wind turbines on the grid voltage and frequency has been presented in this paper through rigorous simulation studies carried out using the professional simulation software PSS/E. The simulation studies are carried out on a power grid network model that includes hydro, gas and wind generation under different voltage and frequency contingencies or disturbances. Models of commercially available DFIG-based variable speed wind turbines from top manufacturers have been used in the simulation studies. The effect of inertia, loss of generations and loads on the system frequency, as well as the impact of different faults on system voltage are investigated and thoroughly analyzed. Furthermore, this study also includes the assessments of grid code requirements under for high penetration of DFIG based wind turbines in the power grid. Critical analysis of the simulation studies reveal that DFIG-based wind turbines are capable to contribute to system frequency and voltage regulation under different contingencies or network disturbances.