Performance Assessment of an Isolated DC Nanogrid with Boost Type Interfaces and Current-Mode Primary Control

Abstract

Isolated DC nanogrids based on stochastic renewable energy sources and variable loads rely on Energy Storage (ES) units for voltage regulation and power quality. A hierarchical control architecture with primary and secondary layers is often used. This paper discusses the performance of an isolated DC nanogrid with Boost type interfaces and current-mode primary control. The former allows the use of low voltage distributed energy resources while the latter, the use of a single control loop in the primary control. A design approach for the output capacitor of the interface is proposed. It deals with the stability issue caused by the droop factor in primary control. This is verified by simulations as well as the impact of the State-of-Charge (SoC) control scheme of the ES units and secondary control on the voltage regulation of the DC nanogrid.