Inertial Response using Backstepping Control from DFIG based Wind Power Plant for Short-Term Frequency Regulation

unlike traditional synchronous generation sources, renewable power generators do not instinctively engage in frequency regulation. Specifically, the Doubly-Fed Induction Generator (DFIG) underlying wind turbines (WTs) provide a destitute response to frequency deviations, since the power electronic interface, which is normally controlled only to ensure a Maximum Power Point Tracking (MPPT) operation, almost totally dissociates the mechanical speed from the electrical network frequency. For this reason, the expansion of Wind Power Penetration (WPP) will raise some red flags in terms of power system operation. Since an important WPP promotes the shutdown of many conventional power plants, which reduces the system total inertia and curtails the primary reserves that are usually needed to secure the stability and reliability of the power system by retaining the frequency within a tolerable range of deviation. Accordingly, this paper introduces a supplementary control loop that allows, in case of frequency drop, the DFIG to discharge a part of the kinetic energy stocked in the WT spinning masses in order to provide active power support for the electrical network during the transient. Nonlinear backstepping (BS) control schemes are used to strengthen the robustness of the system. Simulation results in Matlab/Simulink environment, in a case of study considering an isolated power system that consists of DFIG based wind farm (WF), four synchronous generators, static load, and an unexpected frequency disturbance, demonstrate the validity of the designed control approach.