Optimization of photovoltaic-based microgrid with hybrid energy storage: A P-graph approach

Abstract Renewable energy is the key to decarbonize energy use despite the growing global energy demand. However, energy storage is required to tackle the supply-demand mismatch caused by the intermittent nature of renewable energy sources. As each type of energy storage has a distinct discharge duration, a hybrid energy storage system can be more cost-effective than a single energy storage system. While various process integration tools have been employed for the optimization of microgrid with hybrid energy storage, a graph theoretic algorithm known as P-graph allows the identification of optimal and near-optimal solutions for practical decision making. P-graph involves modelling by graphs and the embedded accelerated branch-and-bound algorithm enables efficient determination of optimal solution. This study proposes a multi-period P-graph optimization framework for the optimization of photovoltaic-based microgrid with battery-hydrogen energy storage and the proposed approach is demonstrated through two case studies. Results showed that the optimal cost of microgrid with hybrid battery-hydrogen storage is 704,990 USD/y, a carbon price of 1000 USD/t and above is required to make it more economical than conventional electricity use. Replacing the hydrogen storage system with grid support reduces the total cost and required carbon price to 262,334 USD /y and 300 USD /y respectively.