Adaptive Hybrid Turbine Switching for Drought-Resilient Hydropower Operation

This study evaluates hydroelectric performance under drought conditions through a scenario-based hybrid turbine operation strategy. Drought-induced hydrological variability leads to fluctuations in streamflow and consequently affects energy production continuity. In response, a Francis–Pelton hybrid configuration was assessed under five drought scenarios classified using the Streamflow Drought Index (SDI).Monthly averaged synthetic discharge data were employed to represent idealized hydrological conditions. Turbine selection was determined using a relative discharge (RD) criterion, whereby the Francis turbine operated under normal to severe drought conditions, and the Pelton turbine was activated during extreme drought. Energy production was calculated using the conventional hydropower formulation incorporating discharge, net head, operation time, and representative efficiency values derived from the literature.Results indicate that the hybrid configuration improves low-flow performance and provides an additional annual energy gain of approximately 8% (4.86 GWh) compared to a single-turbine system. This corresponds to an increase in capacity factor from 49.4% to 53.3%.The findings are based on synthetic monthly data and assumed efficiency parameters and therefore represent an idealized technical assessment rather than site-specific operational performance. Within these constraints, the study offers a methodological framework for evaluating hybrid turbine applicability under drought-induced hydrological variability.