Seamless Transfer with Multi-functional Capabilities of Solar Photovoltaic Based Grid Interactive Microgrid

With the increasing number of renewables in a microgrid, synchronization of each source becomes an intricate task. This work deals with a SPV-BES based microgrid working in grid tied mode (GTM) and in islanded mode (ISM) besides, seamless mode shift operation is also presented at constant and variable power modes of the grid along a change in solar insolation. A dual filtered FLL (DF-FLL) is utilized to evaluate the phase angle of the grid and load voltages instead of SRF-PLL and comparative results are presented. In GTM, the power conditioning unit works in the current control mode, however, to maintain common point of coupling (CPC) voltage, it works in voltage control in ISM. In order to shift from ISM to GTM, a synchronizing controller is used to track the amplitude of the grid and load voltages, phase difference and frequency. Whenever the signals are found in the range as mentioned in the IEEE 1547-2018 standard, the synchronizing signal goes high. Besides, this work also deals with the mitigation of power quality issues at the CPC. A comparative table of the system with existing microgrid is also presented. Test results depict that the power quality (PQ) index of source current and voltage, are maintained under the IEEE-519 standard.