Low-carbon flexible operation strategy of integrated electricity-gas systems considering dynamic hydrogen injection

Hydrogen doping in natural gas pipelines offers a promising pathway to integrate renewable energy and enable large-scale hydrogen delivery. This paper focuses on the low-carbon flexible operation problem of integrated electricity–gas systems (IEGS) with dynamic hydrogen injection. First, an energy-balance-based quasi-dynamic model is developed to address the different calorific values of the gas mixture in gas network. Second, a hydrogen-mixed gas turbine (HMGT) carbon emission and combustion model based on the system thermodynamics and chemical reaction kinetics is also presented. Third, a dynamic hydrogen doping strategy is leveraged to consider the impact of gas composition variations on HMGT operation and gas system to reflect the value of dynamic hydrogen doping in IEGS. Finally, tractable reformulation with multiple convex relaxation techniques, e.g., McCormick envelope, outer linear approximation, and binary expansion, is tailored to address the nonconvex and nonlinear terms arising from the electrolysis, HMGT, dynamic hydrogen doping, and the convex-concave energy balance-based quasi-dynamic flow model. Numerical results illustrate that the solution gap and pipeline error of the proposed method are fairly small. The dynamic hydrogen doping model can reduce operating costs by 2.78 % and 5.76 % compared to the fixed hydrogen doping strategy.