Electrical load controller for rural micro-hydroelectric systems using a programmable logic controller

Micro-hydroelectric systems convert the energy of moving water into electric energy. In rural settings, micro hydroelectric systems are run at full power at all times to avoid the cost of expensive electromechanical controls. That in turn causes the generator to produce its maximum rated power. If the electric energy supply and demand are not matching, the generator eventually fails. Electronic load controllers have been proposed in the literature to better match the demand and supply. In this paper, an electrical load controller is implemented using a programmable logic controller (PLC). PLCs are used in industrial applications and can withstand high levels of dust, dirt and moisture making them very suitable for micro-hydroelectric applications. The proposed controller monitors the frequency of the generator. It will dynamically balance the system power by incrementing or decrementing the power rating of a resistive heating load. The controller was experimentally tested in a lab using a micro-hydroelectric emulator. The emulator includes a 13.8 kW generator, a 10 Hp motor, a motor drive and the PLC controller. The results showed that the PLC controller is a viable load control system for such an application.