Active Resonant Damper with Control Strategy Based on Inverter Output Conductance Optimization under Weak Grid Conditions

With the significant penetration of renewable energy sources and the widespread application of power electronic devices, the characteristics of the grid-source-grid-load system are becoming increasingly complex, particularly in weak grid environments. The interaction between grid-connected inverters and grid impedance may lead to harmonic resonance phenomena, which can adversely affect the stable operation of the entire system. This paper investigates an active resonant damping method specifically designed for weak grid conditions. It provides a detailed description of the circuit topology and operating principles of an LC series filtered active resonant damper. Furthermore, the paper establishes an output admittance model for the LC series filtered active resonant damper and analyzes the impact of its three different equivalent damping forms (R, L, and C) on the admittance frequency characteristics during access to the weak grid. Based on the resistive active damper, the paper designs the LC filtering parameters, virtual resistance, and control parameters to ensure its passive nature within the Nyquist frequency range, aiming to achieve stable operation of the weak grid system. Finally, the effectiveness of the proposed method is verified through hardware-in-the-loop simulations and experiments.