Bi-level Optimal Design of Integrated Energy System with Synergy of Renewables, Conversion, Storage and Demand

Biogas-solar integrated energy system (IES) can effectively utilize renewable energy and is helpful to carbon neutrality, but its performance improvement relies on the utilized optimal design methods. The optimal design of system needs to consider not only the combination of capacity and operation, but also the synergy of biogas production, energy conversion, storage and demand. Therefore, this study proposes a bi-level optimal design method of the biogas-solar IES. First, a thermodynamic model of biogas production and an electrical demand response (DR) program are introduced to construct a synergy optimal design problem. Then, the optimization problem is formulated as a bi- level iterative model. The upper-level model aims to improve the IES economy and optimizes the capacities of renewables, energy conversion and storage components; the lower-level model minimizes the operation cost and optimizes the operation scheme of supply and demand sides. And the iterative optimization mechanisms between the two levels are established. Finally, a hybrid algorithm combining a genetic algorithm and sequential quadratic programming method is proposed to solve the bi-level model. Simulation results show the advantages of the proposed method in reducing total cost and carbon emissions.