Equivalent inertial time constant of doubly fed induction generator considering synthetic inertial control

The integration of large-scale doubly fed induction generators (DFIGs) into power system leads to the deterioration of the dynamic frequency characteristics in case of power shortage. One effective way to address this deterioration is through synthetic inertial control. However, a quantitative representation of the synthetic equivalent inertial time constant of DFIG (Heq) is greatly needed for research on the dynamic frequency characteristics of wind power-incorporating systems. This study introduces the traditional synthetic inertial control technique of DFIG, and reveals that the dynamic inertial response process is influenced by both the inertial controller and the speed controller. Expressions of Heq in the frequency and time domains were mathematically derived, and the accuracy of Heq was verified by comparing the calculated and simulated values. The 3-stage time varying characteristics of Heq are detailed, and the resulting mechanisms are analyzed.