Mitigating Non-Dissipativity of LCL-Type Grid-Connected Inverters via Active Damping Without Additional Sensors

초록

Passivity theory provides a useful design framework for Passive Damping (PD) and Active Damping (AD) to ensure the stability of the LCL-type Grid-Connected Inverter (GCI). PD can serve as a simple and effective approach for ensuring passivity over the full frequency range, as it does not suffer from discretization issues. However, relying solely on PD can lead to excessive power loss; thus, AD should be incorporated to mitigate non-dissipativity, thereby reducing the associated power loss. Therefore, this paper proposes a practical AD method that mitigates non-dissipativity without additional sensors by utilizing the currents already measured for feedback current control. The proposed method can be readily applied to both Grid-side Current Feedback (GCF) and Inverter-side Current Feedback (ICF) control schemes, and a step-by-step design procedure is provided to facilitate implementation. The proposed AD reduces the Negative Peak (NP) of the output admittance by approximately 76% for GCF control and 52% for ICF control. Consequently, the PD loss required to ensure passivity over the full frequency range is less than 0.006% of the rated power. Experimental validation is performed using a 2.2-kW laboratory-scale setup designed based on the proposed procedure, demonstrating that the proposed AD effectively mitigates non-dissipativity without requiring additional sensors.

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