Operating point sensitivity analysis and dynamic stiffness assessment for grid-side converter control of DFIG wind turbines

The control for the grid-side converter (GSC) of the doubly-fed induction generator (DFIG) wind turbine system is established. The full transfer function of the GSC control is derived. The simplifications of the full transfer function to transfer function (by ignoring inner loop) and then to simplified transfer function (by neglecting the appropriate term of the transfer function) are undertaken and validated by MATLAB results. In order to calculate the tuning parameters, the simplified second order approximated transfer function is also extracted. The dynamic stiffness equations are obtained to validate that the DFIG system proposed in this paper is stiff enough against the disturbance variations. Finally, the operating point sensitivity analysis and the dynamic stiffness assessment for the GSC are carried out and substantiated by PSCAD results.