Improving energy production by using diverse rated units in small hydropower plants

[Display omitted] •Improved energy production in hydropower plants.•Improved energy units’ ratings in hydropower plants.•State-of-the-Arts of successfully manufactured and applied hydro turbines.•Determination of low flow factor in hydro turbines.•Efficiency as flow dependent modeling in hydro turbines. The usual criteria for designing hydropower plants include the distribution of the rated power among equally rated generating units in such way that a single spare part could be used in whatever damaged unit. However, modern cutting tools and machining stations available to the manufacturing sector allow quick production and access to the main components of hydropower plant units, including valves, turbines, and generators, in such a way that they can be immediately ordered as needed. Storing expensive spare parts is not necessary anymore, reducing the number of fixed assets, and increasing the economic feasibility of investments. Additionally, using the same rated generating units may result in undesired energy losses and operational limitations as explained in this paper. Therefore, this paper proposes a new methodology for sizing unequal units’ rate for a given hydropower plant power, updating usual criteria, maximizing the energy production and optimizing maintenance needs. The proposed method is described and applied in two case studies, resulting in energy generation improvements at more than 1% when compared with the traditional approach, which is equivalent to a reduction of at least 12.5% to about 25% of the current energy conversion losses in hydro turbines.