Optimal Control of Hydrokinetic-powered Pumpback System for a Hydropower Plant in Dry Season: A Case Study

Low hydropower generation in dry season due to low water levels in hydropower dams is a common problem, particularly in drought-prone regions such as Southern Africa. In this paper, an optimal hydrokinetic-powered pumpback retrofit for recycling a part of the dam's downstream discharge to optimise the performance of the dam is proposed. The optimisation problem is formulated as a multi-objective problem to minimise grid pumping energy, maximise the use of hydrokinetic energy for pumping operation and maximise restoration of the dam volume through the pumpback operation. Simulation results of the proposed model using a practical case study show the potential of the model to increase the energy yield of the plant by 39 to 41.48% in the dry season.