Abstract: Under the strong impetus of the "dual carbon" strategic goal, building efficient and low-carbon integrated energy systems has become an important task. In response to the high carbon emissions and operating costs of the energy system, as well as the low energy utilization rate, this paper proposes a low-carbon economic operation optimization model for the integrated energy system based on multi-stage utilization of hydrogen production from electricity. Firstly, by combining two-stage power-to-gas conversion with carbon capture and storage technology, the internal carbon recycling of the system can be achieved. On this basis, a multi-stage utilization system for electric hydrogen production is constructed, which includes methane preparation, gas mixed with hydrogen, and hydrogen storage, in order to improve the utilization efficiency of hydrogen energy. Finally, taking into account the ladder carbon trading mechanism, an optimization model is established with the goal of minimizing the total operating cost. The case analysis shows that the optimization model proposed in this paper increased the utilization rate of hydrogen energy by 8.2%, promoting the multi-level utilization of hydrogen energy. At the same time, with the help of this model, the total operating cost and carbon emissions of the system were reduced by 7.58% and 10.1% respectively, effectively advancing the low-carbon economic operation of the integrated energy system.

Key words: integrated energy system, ladder carbon trading mechanism, carbon capture and storage, two-stage power-to-gas conversion, gas mixed with hydrogen