Passivity Enhancement Using Positive Active Damping for LCL-Type Grid-Connected Inverters with Inverter-side Current Feedback

초록

An LCL-type Grid-Connected Inverter (GCI) can become unstable due to grid resonance caused by other systems connected to the Point of Common Coupling (PCC). Since grid resonance is difficult to estimate, designing a GCI to maintain stability under conditions where grid resonance exists is challenging. This issue can be effectively addressed by properly designing Active Damping (AD) and Passive Damping (PD) to ensure the passivity of the GCI based on passivity theory. PD does not suffer from sampling issues, making it a simple and effective approach to guaranteeing passivity over the full frequency range. However, ensuring passivity solely with PD can lead to unnecessary power losses. This issue can be addressed by incorporating AD to enhance passivity, thereby reducing the passive component size required for PD. This paper proposes a method to enhance the passivity of the LCL-type GCI with Inverter-side Current Feedback (ICF) by applying positive AD using the inverter-side current.

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