Impedance-based models of wind generators are widely used to analyze unstable oscillations between the grid and the control system of wind park generators. However, it is unclear what are the key control parameters that must be considered in the models at different frequency ranges (subsynchronous, near synchronous and high frequencies). The models can be either highly detailed, at the expense of complex algebraic derivations, or oversimplified, but unable to reliably predict control-to-grid instabilities.