A Hybrid Technique for Minimizing Ripple in DC Nanogrids

The increase in Photovoltaic (PV) penetration in residential nanogrids suffers from the reliability mismatch between the system components; mainly the challenges imposed by the capacitors placed at the DC-link and the voltage ripple across them. This paper proposes a hybrid two-level control solution to minimize the DC-link capacitor voltage ripple while reducing the required capacitance for DC nanogrids. Moreover, the overall reliability of the nanogrid is increased by enhancing the lifetime of the capacitors while utilizing smaller passive elements and maintaining high power quality. The proposed approach impacts the operation of emerging PV-based nanogrids since they improve the power quality at the DC and AC ports via introducing a hybrid mechanism with power decoupling, enhance the system reliability, reduce the overall cost and eliminate the impact of double-line frequency for single-phase grid-connected DC nanogrids. The proposed approach can eliminate the impact of double-line frequency and higher-order frequencies that appear at the DC-link voltage while providing various auxiliary services. The theoretical analysis are validated via hardware-in-the-loop, the results demonstrate promising performance and effective minimization of voltage ripple.