Zhe Xu

Modern energy internets and large-scale industrial systems are becoming increasingly complex. Consequently, the rapid response capability of energy infrastructure during sudden failures has become a core element to ensure the stable operation of the social economy. Emergency repair path planning (ERPP) is a complex nonlinear combinatorial optimization problem. It is characterized by dynamic uncertainties, such as fluctuating task durations and variable traffic accessibility. This paper proposes a cross-regional emergency repair path planning (CR-ERPP) optimization model considering dynamic path conditions. The model takes into account jurisdiction ownership, cross-regional dispatch costs, path weights (congestion coefficient, grade coefficient, quality coefficient) and accident risk levels. The primary objective of this model is to minimize the total repair cost. Furthermore, an Adaptive Bitterling Fish Optimization with Evolutionary Game Theory (ABFO-EGT) is developed. It introduces adaptive mechanisms, evolutionary game theory, and a symmetric mutation strategy. These enhancements are designed to overcome the inherent limitations of traditional swarm intelligence algorithms, namely unbalanced search behavior and premature convergence to local optima. Performance analysis demonstrates that the ABFO-EGT algorithm exhibits superior convergence stability and global search capability. Case study results show that the proposed method significantly reduces the total repair cost. Specifically, the cost is reduced by 33.2% compared to manual decision-making, 27.6% compared to the GWO algorithm, and 9.1% compared to both the ACO and PSO algorithms. This study provides an efficient and reliable decision support tool for emergency management of large-scale energy systems.

Hydrogen-blended natural gas (HBNG) enhances the sustainable use of fossil fuels and significantly boosts hydrogen utilization rates. Thus, the optimal design of HBNG distribution pipelines constitute a pivotal research focus for future advancement. This paper develops a model for optimizing pipeline layouts to minimize investment costs, providing a reference model on optimizing HBNG distribution pipes. An innovative multi-strategy enhanced Harris Hawk algorithm (GHHO) is proposed. The GHHO algorithm enhances the original HHO algorithm chiefly by incorporating the chaos reverse learning initialization strategy, AO global search, a non-linear escape energy factor, and an adaptive T-distribution mutation strategy. Experimental tests are performed on the CEC2017 and CEC2022 test datasets to validate the performance of the enhanced method. The results indicate that the GHHO algorithm improves the convergence and stability of the original algorithm, exhibiting considerable advantages over rival algorithms. Additionally, the GHHO algorithm is applied to obtain the optimal layout schme of the practical HBNG pipeline. Compared with other methods, this method reduces pipeline length and investment cost by at least 7.03% and 4.1%, respectively. The findings definitively confirm the efficacy of the layout optimization model and GHHO algorithm, bearing substantial significance for advancing the sustainable growth of HBNG pipeline networks.

The development of hydrogen-blended natural gas (HBNG) increases the risk of gas transportation and presents challenges for pipeline security in utility tunnels. The objective of this study is to investigate the diffusion properties of HBNG in utility tunnels and evaluate the effectiveness of various ventilation mechanisms. The numerical simulation software Fluent 2023 R1 is applied to simulate and analyze the leakage of small holes in a HBNG pipeline in the natural gas compartment. By examining the leaking behavior of HBNG through small holes in different circumstances, we aimed to identify the most unfavorable operational situation for leakage. Subsequently, we analyzed the ventilation strategy for sub-high-pressure pipes at various pressure levels in this unfavorable condition. This study’s findings demonstrate that blending hydrogen improves the gas diffusion capacity and increases the likelihood of explosion. The primary factors that influence the pattern of leakage are the size of the leaking holes and the pressure of the pipeline. The gas compartment experiences the most unfavorable working conditions for natural gas pipeline leaks when there are higher pressures, wider leak openings, higher hydrogen blending ratios (HBRs), and leaks in close proximity to an air inlet. When the HBR is 20%, the minimum accident ventilation rates for pressures of 0.4 MPa and 0.8 MPa are 15 air changes per hour and 21 air changes per hour, respectively. The maximum allowable wind speed for accident ventilation is 5 m/s, as regulated by China’s national standard, GB 50838-2015. This regulation makes it difficult to minimize the risk of leakage in a 1.6 MPa gas pipeline. It is recommended to install a safety interlock device to quickly shut off the pipeline in the event of a leak in order to facilitate the dispersion of the substance.

Urban underground construction projects are intertwined vertically and horizontally, and adjacent confined spaces such as water supply and drainage pipelines, side ditches and underground canals may exist near buried gas pipelines. Once the buried gas pipeline leaks, the gas will diffuse into the confined space through the soil and even enter the residential room by the confined space, which brings serious potential safety hazards. In this paper, the underground adjacent confined space hazardous boundary (HB) of underground gas pipeline leakage was defined, the distribution properties of gas leakage diffusion flow field were analyzed by numerical simulation and the distribution law of gas entering the confined space was studied. Using the least-squares method and multiple regression theory, the gas concentration prediction model in the adjacent confined space of buried gas pipeline leakage was established, the HB calculation model was further deduced, and the HB drawing board was drawn. The results showed that in the initial stages, the internal and external pressure and velocity distribution of the pipeline near the leakage hole were unstable, reaching a stable state after 60 s, and then the reverse flow occurred in the pipeline downstream of the leak hole. Reducing the minimum construction distance between the buried gas pipeline and the confined space improved the gas distribution concentration in the confined space. When the minimum construction distance increased from 3 m to 9 m, the gas concentration distribution decreased from 90.21% to 0.88%. Meanwhile, increasing the pipeline pressure and leakage diameter enhanced the gas concentration distribution in the confined space. The HB calculation model and HB drawing board realize the rapid determination of the HB between buried gas pipeline and confined space and offer a more reasonable basis for the design of gas pipeline safe distance in urban underground engineering construction.