Conceptual Studies of a Smart, Self-Sufficient Energy System Utilizing Modular Multiport Converter for Connecting Green Generators via a DC Bus

Abstract:
Today, diesel generators are often used to supply off-grid energy consumers (e.g. residential self-sufficient farms), to support weak grids, or to supply energy in the event of an emergency or disaster. These diesel generators are relatively small, often mobile and can be connected to existing infrastructure via conventional AC lines. However, their high carbon footprint and relatively low efficiency are significant disadvantages, which could be mitigated using a flexible system based on a battery, fuel cell, electrolyser, hydrogen storage and renewables integration. Using a DC coupling between renewable generators and energy storage systems, the conversion losses of several conventional AC converters can be avoided, which increases efficiency at the system level and saves valuable energy for off-grid use. Due to its modularity, such a system can be adapted to a wide range of low and medium power in different geographical and climatic conditions. To increase system efficiency and power density even further, the newest power electronics technologies, such as gallium nitride (GaN) power semiconductors, can be utilised for the required DC/DC converters. GaN power semiconductors operate at higher switching frequencies and possess higher thermal conductivity. This enables GaN-based converters to process more power in a smaller footprint at significantly reduced losses, leading to higher efficiency. In addition, a newly developed central energy management system is used to increase the system's degree of autonomy and guarantee its operational readiness and optimal use of the different energy generation and storage systems throughout the year.