Refined modeling and co-optimization of electric-hydrogen-thermal-gas integrated energy system with hybrid energy storage

To further explore the multi-energy complementary potential on multi-time scales under variable operating conditions, a refined modeling and collaborative configuration method for Electric-Hydrogen-Thermal-Gas Integrated Energy Systems (EHTG-IES) with hybrid energy storage system (HESS) is proposed in this paper. To commence with, an advanced operation model for the EHTG energy conversion equipment is formulated by incorporating their nonlinear operating characteristics under variable operating conditions. Next, the distinct features of HESS with different energy medium are accurately depicted with various effective linear-reduction and relaxation strategies. Then, the coupling design day method and the intra-day and inter-day state superposition strategy are combined to efficiently model the time horizon. Lastly, a co-optimal configuration model of the EHTG-IES is devised, with the aim of minimizing total annual cost. The case study validates that the refined modeling of coupled components leads to a 3.18% reduction in cost and 5.05% reduction in carbon emissions significantly. This paper also assessments the synergy and substitution benefits of multiple low-carbon technologies and finds that diurnal and seasonal hydrogen storage have a large part of overlapping roles, and hydrogen-based system contributes a deeper utilization of seasonal thermal storage. The sensitivity analysis indicates that the current carbon tax policy has a negligible impact on the carbon emissions, equivalent to about 1% of the gas price, but appropriately increasing attention on low carbon allows for an emission decrease of 28.62% at a cost increase of 4.38%.