School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230009, China

With the increasing proportion of wind power, the stability problem of the power synchronized grid-forming doubly-fed induction generator (PS-DFIG) connected to the weak grid has received extensive attention. Compared with the power response characteristics of phase-locked synchronized grid-following control, the interaction between the active power loop and the rotor speed loop in PS-DFIG based on grid-forming control is more likely to cause low-frequency torque oscillation. First, the small-signal model of active power and generator speed of the PS-DFIG system is established, and the coupling characteristics of active power and rotor speed responses are analyzed. On this basis, the influence of the loop characteristics of the PS-DFIG system on the low-frequency oscillation of the drivetrain is studied by means of the electrical damping analysis method. Then, based on the multi-loop bandwidth design criterion, the differential feedforward method is introduced into the active power loop to improve the active power bandwidth. At the same time, the torque compensation is added to the output of the rotor speed loop, which improves the electrical damping characteristics of the electromagnetic torque, relatively improves the parameter robustness of the power loop, and effectively reduces the risk of low-frequency oscillation of the drivetrain system of PS-DFIG system. Finally, the experimental verification is carried out on the hardware-in-loop platform of RT-LAB.