Mitigation of Converter-Grid Resonance, Grid-Induced Distortion, and Parametric Instabilities in Converter-Based Distributed Generation

This paper presents a robust interfacing scheme for distributed generation (DG) inverters featuring robust mitigation of converter-grid resonance at parameter variation, grid-induced distortion, and current-control parametric instabilities. The proposed scheme relies on a high-bandwidth current-control loop, which is designed with continuous wideband active damping against converter-grid disturbances and parametric uncertainties by providing adaptive internal-model dynamics. First, a predictive current controller with time-delay compensation is adopted to control the grid-side current with high-bandwidth characteristics to facilitate higher bandwidth disturbance rejection and active-damping control at higher frequencies. Second, to ensure high disturbance rejection of grid distortion, converter resonance at parameter variation, and parametric instabilities, an adaptive internal model for the capacitor voltage and grid-side current dynamics is included within the current-feedback structure. Due to the time-varying and periodic nature of the internal-model dynamics, a neural-network-based estimator is proposed to construct the internal-model dynamics in real time. Theoretical analysis and comparative experimental results are presented to demonstrate the effectiveness of the proposed control scheme.