  A hybrid hydropower power plant is a conventional HydroPower Plant (HPP)
augmented with a Battery Energy Storage System (BESS) to decrease the wear and
tear of sensitive mechanical components and improve the reliability and
regulation performance of the overall plant. A central task of controlling
hybrid power plants is determining how the total power set-point should be
split between the BESS and the hybridized unit (power set-point splitting) as a
function of the operational objectives. This paper describes a Model Predictive
Control (MPC) framework for hybrid medium- and high-head plants to determine
the power set-point of the hydropower unit and the BESS. The splitting policy
relies on an explicit formulation of the mechanical loads incurred by the HPP's
penstock, which can be damaged due to fatigue when providing regulation
services to the grid. By filtering out from the HPP's power set-point the
components conducive to excess penstock fatigue and properly controlling the
BESS, the proposed MPC is able to maintain the same level of regulation
performance while significantly decreasing damages to the hydraulic conduits. A
proof-of-concept by simulations is provided considering a 230 MW medium-head
hydropower plant.
