Rotational Reference Frame Control of DFIG-Based Wind Turbines for Inertial Frequency Response

The rapid increase of wind power penetration has threatened the frequency stability of regional power grids, and the loss of system inertia is viewed as the key issue to be solved. Catering to this problem, this paper proposes a rotational reference frame (RRF) control method for the doubly-fed induction generator based wind turbines (DFIG-WTs) to improve the inertia frequency response. An anti-frequency-deviation phase delay is introduced into the phase angle measured by the phase-locked loop (PLL). The dq-RRF of the control system of a DFIG-WT is rotated such that the voltage vectors of the stator and the grid-side converter (GSC) moved like the internal voltage vector of a synchronous generator. Frequency domain analysis is carried out to evaluate the stability of the system and the robustness to the variations of control parameters of the DFIG-WT. Both simulation studies and hardware-in-the-loop experiment are carried out for frequency and active power response. Results show that the RRF controller not only inherits stronger robustness and simpler structure, but also is able to provide stronger inertial support against the drop of system frequency than the widely used synthetic inertia control (SIC) method.