Optimal energy management of a grid-connected micro-hydrokinetic with pumped hydro storage system

Abstract

Renewable energy sources are the key alternatives to mitigate the issue of greenhouse gases (GHGs) and to meet the ever increasing electricity demand. In South Africa, most energy is consumed by the industrial sectors when discretely compared to other sectors. Industrial consumers can reduce their electricity costs by creating an optimally managed onsite renewable energy system. Hydrokinetic is a promising renewable technology that has proved to offer a cost-effective electrification solution in areas with flowing water resources when compared to solar and wind technologies. This paper proposes an optimal energy management model for a grid-connected micro-hydrokinetic pumped hydro storage (MHK-PHS) system supplying the industrial load profile. The aim of the study is to investigate the behavior of model when minimizing the grid energy costs through power-flow control variables and time-of-use (TOU) tariff scheme. The optimization problem has been solved through the use of the linprog solver in the MATLAB’s optimization toolbox for a period of 192 h as a means of including week days and weekend days. The simulation results show that the developed model can assist the onsite MHK-PHS system to optimally reduce the electricity cost for the industrial load profile. An 86% grid cost saving has been achieved through the optimally managed MHK-PHS system.