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A low-voltage direct current (LVDC) distribution system comprises a rectifier, a DC network, and customer-end inverters (CEI) responsible for the AC supply to the electricity end-users. The CEIs can be implemented as single-phase or three-phase ones; in this paper, feasible single-and three-phase topologies are introduced and their losses are calculated using nine different power switches. Three commercially available IGBT, MOSFET, and SiC MOSFET power switches are selected for comparison. In this application, a galvanic isolation between the DC network and the customer is required. The isolation is implemented by using an isolating DC/DC converter at the CEI supply, and therefore, the input voltage of the CEI can be different from the DC network voltage. In this paper, the effect of the supply voltage level on the losses of the CEI is calculated for the nine power transistors in single-and three-phase topologies.

This article focuses on the overall system engineering aspects of low voltage DC (LVDC) electricity distribution.. The interdependencies between different parts of an LVDC distribution system are discussed emphasising the issues related with the interconnection of user-end LVDC installations and public LVDC systems. The main objective is to illustrate the importance of the total system engineering over the piecewise design approach. The aspects affecting on the selection of the DC voltage level, system structures and earthing arrangements are considered. A methodology for selecting the technoeconomic optimal voltage level within the boundary conditions set by the DC system application and the operating environment is introduced with example calculations. Presented discussions and results provide support especially for the development of the standardisation of the LVDC technology

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When a low-voltage DC distribution system installation is realised in a public power distribution network, an extensive specification is required to ensure electrical and equipment safety and compatibility between the existing grids and customer-end installations. The goal of the paper is to give to a reader an understanding what is required for safe and reliable operation of the LVDC distribution in an actual distribution environment. The paper discusses the mechanical and electro-technical aspects of the pilot installation. The focus is on the common system and power electronics specifications.