  Virtual inertia controllers (VICs) for wind turbine generators (WTGs) have
been recently developed to compensate for the reduction of inertia in power
systems. However, VICs can induce low-frequency torsional oscillations of the
drive train of WTGs. This paper addresses this issue and develops a new
nonlinear VIC based on objective holographic feedbacks theory. This approach
allows transforming the objectives that require improvement into a completely
controllable system of Brunovsky's type. Simulation results under various
scenarios demonstrate that the proposed method outperforms existing VICs in
terms of suppression of WTG low-frequency drive-train torsional oscillations,
enhancement of system frequency nadir as well as fast and smooth recovery of
WTG rotor speed to the original MPP before the disturbance. The proposed method
is also able to coordinate multiple WTGs.

Systems and Control;Systems and Control