Potential energy savings by using direct current for residential applications: A Danish household study case

摘要

This paper presents a study of the potential energy savings by implementing dc distribution systems for residential applications. In general, it is commonly accepted that the use of dc voltage improves the efficiency of the distribution, due to a decrease in the conduction losses and an efficiency improvement in the power converter units. However, for residential applications, the efficiency is not always improved. A grid connected residential microgrid, with renewable energy sources (RES), energy storage systems (ESS) and local loads, is presented in this work. The microgrid has been modelled for an ac-based and dc-based distribution system, in order to simulate and assess the overall efficiency of the system, for different distribution technologies. Commercially available power supplies for home electronics have been modelled and modified to work with both ac and dc distribution voltages. A Danish household has been used as study case. This study has shown that, depending on the application, architecture, consumption and generation profiles, a dc distribution system might not bring any efficiency improvement, especially when the dc voltage is supplied from a grid rectifier that works at low loads. However, for isolated microgrids, the use of dc voltage has the potential to bring a significant efficiency improvement. Nevertheless the potential for cost reduction in all scenarios is very promising.