Stability Assessment of Self-Synchronizing Active Damper

With the increasing penetration of renewable energy and the application of large-scale renewable power plants (RPPs), the power grid experiences oscillation problems. Active damper (AD) is one of the effective solutions to stabilize the renewable power grid without the necessary effort to improve the control schemes of large numbers of power converters in RPPs. However, existing AD is synchronized with the electric grid by the conventional phase-locked loop (PLL), which may cause coupling and result in oscillations. Thus, this paper proposes a self-synchronizing AD, which can eliminate the coupling effect existing in the conventional PLL. The stability of the AD is analyzed by the impedance-based stability criterion. The theoretical comparisons between the self-synchronizing AD and the conventional PLLbased AD as well as the MATLAB/Simulink-based and OPAL-RT-based test results clearly validate the advantages of the proposed AD and the effectiveness of the PLL inclusive modeling.