IHO-FLL Control for Seamless Transfer Between Operational Modes of AC Microgrid With DG Set as Emergency Power Supply

This work endeavors seamless transfer scheme that allows the microgrid to transit from an islanded operating mode to the grid reconnected operating mode. The system operability enhances, and power surety is made available 24x7 while utilizing the diesel generator (DG) set as an emergency power supply. The fuel efficiency and cost effectiveness are ensured by utilizing renewable resources and utility interconnection of the microgrid. The operation of DG set is ensured only in the worst-case scenario when all the power sources have suffered an outage. The mode of operation and its changeover from grid/DG interfaced to grid/DG isolation are considered in accordance to the status of the signal provided to the static transfer switches (STS-1/2). The harmonics appearing in the grid current are eliminated successfully while providing enhanced power quality of grid and voltage of PCC. The modelling of the three phase four wire based microgrid is carried in Matlab and the results of simulation are procured, which depict the smooth mode transition from utility associated operating mode to utility outage mode and vice-versa.