Decoupling active power control scheme of doubly-fed induction generator for providing virtual inertial response

Virtual inertial control (VIC) is implemented in the controller of doubly-fed induction generators (DFIGs) to compensate for the reduction in capability of the frequency regulation. However, the conventional VIC might give negative impacts on improve the frequency nadir due to the coupling power dynamics between the variation of the power references of the maximum power tracking operation (MPTO) and VIC. In addition, when regaining the rotor speed, a double frequency drop (DFD) trends to produce due to the sudden output drop. This paper suggests a decoupling active power control scheme of a wind power plant to improve the frequency nadir and minimize the DFD. To improve the frequency nadir, the proposed VIC suggests various operating power tracking operations to improve the frequency nadir. The variable-coefficient-PI-control based rotor speed recovery strategy (RSRS) is suggested to minimize the DFD and automatically switches to the MPTO. Test results demonstrate that the suggested decoupling active power control scheme with proposed RSRS and VIC strategy can minimize the DFD and reduce mechanical stresses on the wind turbine while enhancing the frequency nadir.