An Experimental Investigation of Various Control Systems for an Archimedes Screw Turbine in a Micro-Hydropower Plant

The control system for a micro-hydropower plant using an Archimedes screw turbine is the focus of this work. Three control systems were implemented based on a Barreda micro-hydropower plant (Spain) currently in operation: an optimal water level control (OWLC) system, a maximum power point monitoring (MPPT) system, and a water level control (WLC) system. The comparison was made using several assessment indicators: electricity production, micro-hydropower plant efficiency, and gearbox fatigue. The electricity production is similar in the OWLC and MPPT systems (energy gain +0.5%) and significantly lower in the WLC system (energy gain -12%). The efficiency of the micro-hydro plant is similar in the OWLC and MPPT systems (average efficiency gain +0.9%) and significantly lower in the WLC system (average efficiency gain -15%). The mechanical stress on the gearbox is similar in the OWLC and WLC systems and significantly higher in the MPPT system. It can be concluded that the OWLC system performs better as concerns the three assessment indicators used, followed by the MPPT system. The WLC system is not recommended for use, due to its low electricity production and low efficiency of the micro-hydropower plant.