Study of the application of bidirectional dual active bridge converters in dc nanogrid energy storage systems

This paper discusses the application of a dual active bridge converter (DAB) as a bidirectional interface between the energy storage system and the main dc bus in a dc nanogrid. A novel control technique based on control loops competition is proposed to perform the energy management between both systems, which allows the dual active bridge to concomitantly regulate the main dc bus and control the battery bank charging process with a four states method.

I. Introduction

Recently, due to the increasing demand on electricity consumption to meet the society needs and to address power generation deficiencies, the electric utilities are becoming more concerned in improving the supply and demand relationship through the development of the national electric grids. The great majority of the world energy demand is supplied by fossil fuels, a situation which prevents the future expansion of this energy production model due to environmental concerns about greenhouse gasses (GHG) emissions and global warming. In this juncture, the participation of renewable energy resources in the electric grid has been growing quickly in the last years. The increase of the penetration of renewable resources, known for fast dynamics and intermittent behavior, in the grid imposes new challenges for the electric utilities in terms of the need for modernization of the power generation, transmission and distribution processes, improvement of the electrical grid energy efficiency and development of new mechanisms for grid control and management that are tuned with the new requirements of this new energy system paradigm. This new concept for the electric grid is being referred as the Smart Grid [1].