Abstract:
The power output by a small hydropower generation unit (SHP) is conventionally estimated as a product
of the net head, admitted flow, and a typical value of efficiency. In case of run of river (RoR) units
however, sub-daily variability of stream flow together with consequent variation of efficiency make the
conventional estimate open to errors.
This paper presents closed form expressions for sub-daily mean output power, sub-daily maximum
likelihood output power, and sub-daily output power variability; all of which serve as useful measures of
RoR unit performance in presence of fluvial micro and macroturbulence phenomena. As part of the
development, bimodal (alternately, multimodal) logistic distributions are established as dependable
statistics for sub-daily flow admitted to a RoR unit.
The concepts are substantiated through an operational RoR case study from Malaysia, and detailed
Monte Carlo simulations based on the same. The three sub-daily performance metrics are shown to form
good basis for comparison between candidate turbine configurations for RoR projects in operation, or
alternately, those under consideration at a planning stage.
