Development of voltage control system for multi-terminal low-voltage DC distribution system

LVDC (Low Voltage Direct Current) distribution systems have advantages over conventional AC distribution systems in terms of power quality, power-conversion-loss reduction, renewable energy integration, and so on. There were pioneering researches into development of LVDC distribution systems but most of them considered radial distribution systems with one grid-connection converter. In this paper, we propose multi-terminal LVDC distribution system that has multiple grid-connection points and integration of distributed energy resources (DERs). The multi-terminal LVDC system can have more reliability and flexibility in electric power provision because it has multiple grid-interfacing AC/DC converters. However, multiple paths for power flows can increase the complexity in system operation and control. This paper proposes a new voltage control method for multi-terminal LVDC distribution systems using multi-agent system (MAS). This paper presents the hierarchical control algorithms to coordinate multiple AC/DC converters and DERs. Simulation studies demonstrates the performance of the proposed method.