An Intelligent Grid integrated BESS Solar PV System to Supply Critical Loads under Grid Outage Condition

Fossil fuel consumption has a negative impact on the environment, for which usage of solar energy is getting momentum. The fundamental issue with grid integration of solar energy is that today's on-grid inverters have the property of requiring a reference signal from the grid. If a grid outage occurs, the on-grid inverter stops functioning because it would not receive any grid reference signal and all the generated power from plant remains unutilized and continuous power supply to critical load is interrupted. This paper proposes an innovative network and control arrangement enabling the generated PV power to be utilized at the moment of a daytime grid outage. When PV doesn't provide enough power during the day, vital loads are powered by the battery, and when there is grid outage at night, battery power is used to power critical loads. This includes an on-grid and an off-grid inverter connected in parallel such that off-grid one takes the critical loads when the on-grid one goes to sleep mode. A fast switching technique maintains continuous supply to the critical load after a grid failure and it keeps the output voltage constant with the fluctuation of the load. At first the proposed inverter has been designed on PSIM platform and simulation is done. Then a hardware prototype is fabricated and tested in the laboratory to validate its functionality.