Operation and Power Management of Grid Connected Solar PV System with Critical load and Battery Backup

This paper attempts a two stage power converter topology with a dc-dc multilevel boost converter (MBC) and a multilevel inverter (MLI) for interfacing PV array with utility grid. The use of MLI has resulted in reduced filter size compared to existing VSI schemes. Provision is also made to supply a critical load connected at the grid terminals which necessitates the use of battery storage in the system. A master controller coordinates between PV array, utility grid and the battery storage and operates any one of these sources in such a way that the critical load receives uninterrupted power. The MLI is controlled by a hysteresis current controller (HCC) which helps in feeding the PV power to the utility grid at UPF. The gate pulses for the IGBT switches in MBC and MLI are generated by dSPACE controller which also takes care of the complete closed loop control. The hardware realization of the proposed scheme is carried out on a PV array of 500 W along with 36 V, 40 Ah storage battery, feeding 110 V, 50 Hz utility grid and a critical load of 110 W. The successful working of the proposed system is validated using simulation and experimental results.