Monitoring and Control of 3-Tier Power Supply

Abstract

Reliable electricity supply is essential for development. As a result, demand for electricity has continued to increase globally, occasioned by the fact that electricity is highly portable and can be transformed from one form to another to meet needs. In Nigeria and most developing countries, electricity supply from the public utility is not only insufficient but highly erratic. The effect of this is adverse on critical and sensitive infrastructure that depend on uninterrupted power supply. Hence, many domestic, industrial and commercial consumers are compelled to acquire one form of alternative source of power supply or another. With this however, when different power schemes are interconnected, there arises the challenge of switching between the power sources not only smoothly, but in a manner that optimizes their use. Solving these challenges forms the focus of this work. This design monitors three independent power sources: Utility Grid of Power Holding Company of Nigeria (PHCN), solar and generator and engages them following preset conditions in a microcontroller. A software program in assembly language drives the microcontroller. Preference is given to the PHCN line, but in the event of failure or abnormal conditions in the PHCN line, the system will effect a changeover automatically to the solar source through contactors, provided the output of the solar source is acceptable, else the system will initiate the starting of the generator and transfer of load to same. This system finds application wherever there is unreliable power supply and interconnected power schemes.