Smart Controller Design for Solar-grid Hybrid System.

Abstract

A hybrid design of a battery charging system and its implementation has been explained in this report. The system has been designed based on a novel algorithm to couple existing solar PV charging and utility supply charging systems. The algorithm has been programmed in a microcontroller that senses the battery voltage and generates appropriate commands to operate a relay that controls the utility grid supply availability by connecting or disconnecting it to the Uninterrupted Power Supply (UPS) system through which the battery is charged. Besides the utility grid supply charging, solar PV also charges the battery whenever it is available through a charge controller. This system ensures continuous power supply and faster charging of the battery. The system has been designed to suit a typical Ugandan scenario where there is intermittent power supply due to power shortage which results in scheduled and unscheduled load shedding. The integration of small sized standalone solar systems to the grid is technically complicated resulting into expensive operation which is not affordable to all. As such, this report presents a smart controller-based design using digital signal processing for cost effective operation of solar grid tied system. The hybrid system is able to size the connected system and deploy the operation strategy so as to get the effective utilization of solar output. The synchronization is not necessary as this method can be effectively altered by the use of load discretization. This gives cheap, efficient, reliable and cost-effective operation. The performance of the system over the wide range of operation and transient states are assured by practical observation and modification. This system is defined to fill the necessity of regions where solar power is used only as backup purposes to charge the battery and is actively dumped during the presence of active grid. These regions include many parts of Uganda where grid cut off is common due to the shortage of energy.