Hybrid AC–DC Microgrid: Systematic Evaluation of Control Strategies

Hybrid ac-dc microgrid architecture is attracting special attention since it combines the benefits of both ac and dc systems. Control of hybrid microgrid presents a significant research and engineering challenge and hence needs increased research efforts. This paper attempts to review control strategies that are reported in the literature for the hybrid ac-dc microgrid. At first, typical and emerging hybrid microgrid power topologies are presented briefly. Various types of interlinking converters proposed for connecting ac and dc subgrids are discussed subsequently. Following this, a detailed discussion on control strategies for satisfying various control objectives is taken up. Control strategies have been systematically reviewed focusing on each of the broad aspects of control namely modeling, power management, coordinated control, stability analysis, power quality, and protection strategies. Finally, the research gaps observed during the review process and possible solution approaches are outlined.

I. Introduction

The conventional electric grid has been planned and structured for centralized generation of electricity predominantly from fossil fuels. The current trend is towards distributed generation of electricity especially from renewable energy sources such as solar and wind energy. Generating and consuming electricity locally is more economical, reliable and efficient, especially for electrification of off-grid or remote communities. This approach has led to a concept of interfacing autonomous and smart electrical networks with bidirectional power flow capability popularly referred to as “microgrids” [1], [2]. Integration of microgrids can improve grids performance and provide increased flexibility to its operation.