Analytical Modeling of Inertial and Droop Responses From a Wind Farm for Short-Term Frequency Regulation in Power Systems

Available inertia and variable droop responses from a wind farm to support the short-term frequency control in power systems are analytically evaluated. The novelty lies in the approach to formulating the inertia constant and primary power reserve for a variable speed wind turbine (VSWT) that operates at derated conditions. The formulations are extended to evaluate the capability of providing inertia and primary frequency support from a wind farm using an aggregated wind speed. As a consequence, the capability as a function of VSWT operating characteristics and conditions is quantified to rationally adjust the frequency controller gains, thereby ensuring stable performance of the wind farms during frequency transients. A modified system frequency response (SFR) model considering available inertial and droop responses from wind farms is developed to well simulate the SFR following wind power fluctuations. The effectiveness of the analytical method is verified through comparisons of the results with those obtained from the empirical method.