Equivalent Modeling and Comprehensive Evaluation of Inertia Emulation Control Strategy for DFIG Wind Turbine Generator

With the increasing penetration of renewable energy in power grid, many inertia emulation control strategies have been proposed to provide extra support to the power grid in system disturbances. To explain the physical resemblance and relations among all kinds of inertia emulation strategies, a proper double-fed induction generator (DFIG) model is proposed based on equivalent electromotive force <inline-formula> <tex-math notation="LaTeX">$\text{E}_{\boldsymbol{r}}^{\mathrm {eq}}$ </tex-math></inline-formula> and equivalent power angle <inline-formula> <tex-math notation="LaTeX">$\delta _{\mathrm {eq}}$ </tex-math></inline-formula>. A co-simulation research platform is also designed based on a real-time digital simulator (RTDS) and GH Bladed simulation software, and the detailed comparisons are made in terms of inertia response performance, weak grid operation stability, secondary frequency drop, and wind tower fatigue load. Research results point out that different control schemes are similar in inertia response while virtual synchronous generator (VSG) control and inertial synchronization control (ISynC) can improve weak grid operation stability, the VSG strategy is also effective in reducing frequency secondary drop and wind tower fatigue load, and the combination of the VSG for RSC and the ISynC for GSC can achieve the best control performance in all evaluation indexes.