Generator and Transformer Efficiency Study for the Design of a Run-of-River Small Hydropower Plant with One Hydro-Turbine

In the design of small hydroelectric power plants (HPS), various individual energy efficiency coefficients are involved, in order to calculate the overall efficiency at different flow levels. In the case of a small hydropower plant with one hydro-turbine, the hydraulic losses of the penstock, the hydro-turbine, the generator and the transformer are mainly taken into account. Of these, the losses of the generator and the transformer are considered constant, across the operating flow range, but without sufficient bibliographic justification. The purpose of this paper is to determine those conditions, for which the above assumption is valid, taking into account core, copper and mechanical losses for a low-speed salient-pole generator, as well as the core and copper losses of the transformer.