MILP-based distributed hydrogen-blended integrated electricity and gas system operation with variable gas properties

Hydrogen-blended integrated electricity and gas system (H-IEGS) can promote cost-effective hydrogen utilization. However, distributed hydrogen blending also causes variable gas compositions across networks and changes the physical properties of gas, which significantly increases problem modeling and solving difficulties. This paper presents a computationally efficient method to solve the H-IEGS operation problem. First, we model the distributed hydrogen-blended gas system with bidirectional gas flows and variable gas properties, including calorific value, specific gravity, and compressibility factor. Based on this, we establish an H-IEGS operation problem, in which hydrogen, electricity, and gas are coupled through power-to-gas (P2G) and gas-fired generators (GGs). Then, we utilize tailored approximation techniques to transform the nonlinear terms of energy conservation equations into linear ones with high accuracy and propose a penalty trust-region-based sequential linear programming (PTR-SLP) method to solve the H-IEGS optimization problem. Simulation results show that the classic SLP method cannot obtain converged results. Our PTR-SLP computes 75.3 % faster than the fixed decreased trust-region SLP method. The increasing hydrogen volume fractions in pipelines reduce operating costs and carbon emissions.