This paper presents an optimal control strategy for a hydropower plant retrofitted with a hydrokineticpowered
cascaded pumpback system in dry season. Pumpback operation aims at recycling a part of the
down-stream discharge back to the main dam to maintain a high water level to optimise the energy value
of the available water. The problem is formulated as a multi-objective optimisation problem to simultaneously
minimise the grid pumping energy demand, minimise the wear and tear associated with the
switching frequency of the pumps, maximise the restoration of the volume of the dam through pumpback
operation and maximise the use of on-site generated hydrokinetic power for pumping operation.
The performance of the proposed cascaded model is compared with the classical single pump pumped
storage model. Simulation results based on a practical case study shows that the cascaded pumpback
model can reduce the pumping energy demand by up to 48.18% and increase the energy yield of the
resultant system by up to 47.10% in dry season.