An Overview on AC/DC Hybrid Microgrid

The concept of microgrid is emerging as one of the most promising solutions that connects/integrates various distributed renewable energy sources to the grid. This paper focuses on a hybrid AC/DC microgrid that inherits AC grid and a DC grid which operates individually or in grid-tied mode. The AC grid comprises of various diesel generator sets (DG), Wind turbine generators (WTG) and AC loads whereas DC grid is connective network of fuel cell generators, DC loads and PV arrays with boost converters. A four quadrant operating three phase converters are used as a coupling mean between AC and DC bus. The converters can act as a either inverter or rectifier. The energy requirement during isolated operation of the system is maintain by Battery Energy Storage System (BESS) which is connected to the DC bus via charging/discharging converter. When an individual grid (AC or DC) is operative, it requires multiple conversions of power for AC and DC loads at user end hence results in less efficient system. Thereby, hybrid AC/DC microgrid avails best solution to avoid losses during multiple conversions. This paper presents an overview, issues and measures to overcome challenges of hybrid AC/DC microgrid.