Multi-Frequency Damping Adaptive Control Strategy for Active Dampers Based on MultiHarmonic Detection

As the interface between new energy and the power grid, grid-connected converters are easy to cause multifrequency oscillation of the system. So, this paper proposes an active damper to dampen multiple harmonics by simulating virtual resistance. The basic idea of the active damper is that use the cascaded multiple Second-Order Generalized Integrator with the Frequency-Locked Loops (SOGI-FLL) to detect and extract the unknown multiple harmonics automatically. Then, for different content of resonance, the active damper adjusts the virtual resistance value adaptively to enhance the stability of the system. Finally, the simulations of MATLAB/Simulink are carried out and the results verify the accuracy and effectiveness of the proposed scheme.