Auto-tuning based resonance damping of grid-connected voltage source inverters with long transmission cable

Resonance phenomenon of a grid-connected voltage source inverter with a long transmission cable is briefly introduced in this paper. Multiple resonant peaks are found to exist in the system and also very sensitive to the cable parameters. The fluctuation of the cable inductance and capacitance would directly affect the resonant frequencies and thereby deteriorate the damping performance of deterministic damping techniques, such as notch-filter based damping method. To effectively damp the resonances, an auto-tuning notch frequency of the notch-filter damping solution is proposed to address potential resonance fluctuation. The autotuning scheme is desired to calculate the resonant peaks online by incorporating the operating status of the inverter and cable, i.e., the cable input voltage and current. The performances and practicalities of the proposed auto-tuning damping technique have been verified by simulations and experiments.