An Optimal Dispatch Method of Integrated Electricity and Gas Systems Incorporating Hydrogen Injection Flexibility

Hydrogen enriched compressed natural gas provides a promising way of decarbonizing integrated electricity and gas systems. Considering the flexible characteristics of hydrogen enriched compressed natural gas, this paper proposes an optimal dispatch method for integrated electricity and gas systems incorporating hydrogen injection. A hydrogen blending transmission model is developed for hydrogen enriched compressed natural gas. The dynamic characteristics and the line pack are captured considering the impacts of hydrogen injection on pipeline transmission and line pack parameters. From the overall system operation aspect, a detailed energy flow model of hydrogen enriched compressed natural gas involving pipeline, compressor, and nodal gas flow balance is established incorporating the coupling relationship with hydrogen volume fraction. This model allows for the consideration of the impacts of time-varying hydrogen volume fractions on the optimal dispatch of systems. A novel estimation model is proposed to effectively determine the hydrogen volume fraction, which considers the impacts of line pack on hydrogen enriched compressed natural gas. Based on the proposed energy flow model, the line pack and the flexible adjustment of hydrogen volume fraction are aggregated into the flexible characteristics of hydrogen enriched compressed natural gas. A low-carbon dispatch method incorporating these flexible characteristics is developed to decarbonize integrated electricity and gas systems. Case studies on two test systems are presented to validate the effectiveness and applicability of the proposed model and method. The simulation results demonstrate that the accommodation levels of renewable energy and green hydrogen injection can be largely enhanced.