Abstract The incorporation of Power-to-Hydrogen (PtH) units as an energy conversion hub can significantly facilitate the transition toward a low-carbon energy system. However, utilizing existing natural gas infrastructure to transport hydrogen produced by water electrolysis leads to several challenges: inhomogeneous gas composition within the gas network, significant changes in the thermodynamic and hydraulic parameters, and substantial shifts in operational states such as pressure, flow, and linepack, which influence the energy flow of the integrated system. Existing literature presents the steady-state flow model and the equivalent energy flow model. Nevertheless, neither can simultaneously capture the transient transition periods or spatial gas quality differences within the gas network. To address these issues, this paper proposes a dynamic optimal energy flow model for integrated natural gas and electrical power system with hydrogen injection. Firstly, according to the fundamental principles of fluid mechanics, the dynamic gas flow model considering heterogeneous gas injection is derived. It quantitatively describes the relationship between hydrogen mass fraction and flow rate at electrolysis nodes, as well as the differences in gas quality at different positions within the pipeline. Secondly, in conjunction with boundary conditions, the intractable. bilinear terms are equivalently reconstructed into variables with physical significance, namely hydrogen mass flow rate. Assumptions of approximate homogeneous mixing and low hydrogen blending ratios are introduced, transforming the PDE-constrained nonlinear model into a linear difference form. Furthermore, the linearized dynamic gas flow is coupled with the DC power flow. By considering operational constraints and targeting the most economical dispatch of the integrated system, the dynamic optimal energy flow is calculated. The proposed model has been applied to systems of different scales. In the illustrative single pipe case, the transient process of pressure, flow, and mass fraction is analyzed. In the small-scale case, the optimal scheduling of the integrated systems with different models and energy conversion node configurations is comparatively assessed. With an upper limit of 2% for hydrogen blending, the equivalent gas production increases by 53.6%, and total carbon emission is reduced by 0.56% compared to systems with power-to-gas (PtG). It demonstrates that the introduction of PtH can enhance energy conversion efficiency and reduce carbon emissions. Moreover, effects such as a reduction in linepack and pressure in the gas network can impact the operating domain, thereby affecting optimization scheduling results. When solving the optimal dispatch of an integrated system consisting of an IEEE 118 case and a 36-node natural gas system, the computation time was only 20.08 seconds. The following conclusions can be drawn from the simulation analysis: (1) Compared with existing models, the proposed model can reflect the spatial and temporal distribution characteristics of state variables, and reveal the time scale difference of gas network after hydrogen blending. (2) With proper assumptions and simplifications, the dynamic flow model possesses good mathematical properties and superior computational accuracy, which is applicable to large-scale optimization problems. (3) The proposed model can be used in decision support for obtaining the optimal operation strategy of the coordinated systems. In addition, the effects of hydrogen blending on the integrated energy system are analyzed. On one hand, it enhances the efficiency of energy conversion stages and reduces carbon emissions. On the other hand, issues like the adaptability of equipment to hydrogen and a decrease in linepack can affect the operating domain of the system. These factors need to be taken into account during dispatch.
Liu Wenxin,Fang Jiakun,Hu Kewei等. Dynamic Optimal Energy Flow in the Integrated Natural Gas and Electrical Power Systems Considering Hydrogen-Blended Transient Transportation Process[J]. Transactions of China Electrotechnical Society, 2023, 38(zk1): 1-17.
[1] 李争, 张蕊, 孙鹤旭, 等. 可再生能源多能互补制-储-运氢关键技术综述[J]. 电工技术学报, 2021, 36(3): 446-462. Li Zheng, Zhang Rui, Sun Hexu, et al.Review on key technologies of hydrogen generation, storage and transportation based on multi-energy complementary renewable energy[J]. Transactions of China Electrotechnical Society, 2021, 36(3): 446-462. [2] 刘玮, 万燕鸣, 熊亚林, 等. 碳中和目标下电解水制氢关键技术及价格平准化分析[J]. 电工技术学报, 2022, 37(11): 2888-2896. Liu Wei, Wan Yanming, Xiong Yalin, et al.Key technology of water electrolysis and levelized cost of hydrogen analysis under carbon neutral vision[J]. Transactions of China Electrotechnical Society, 2022, 37(11): 2888-2896. [3] 任若轩, 游双矫, 朱新宇, 等. 天然气掺氢输送技术发展现状及前景[J]. 油气与新能源, 2021, 33(4): 26-32. Ren Ruoxuan, You Shuangjiao, Zhu Xinyu, et al.Development status and prospects of hydrogen compressed natural gas transportation technology[J]. Petroleum and New Energy, 2021, 33(4): 26-32. [4] 王玮, 王秋岩, 邓海全, 等. 天然气管道输送混氢天然气的可行性[J]. 天然气工业, 2020, 40(3): 130-136. Wang Wei, Wang Qiuyan, Deng Haiquan, et al.Feasibility analysis on the transportation of hydrogen-natural gas mixtures in natural gas pipelines[J]. Natural Gas Industry, 2020, 40(3): 130-136. [5] 于子龙, 张立业, 宁晨, 等. 天然气掺氢管道输运及终端应用[J]. 力学与实践, 2022, 44(3): 491-502. Yu Zilong, Zhang Liye, Ning Chen, et al.Natural gas hydrogen mixing pipeline transportation and terminal application[J]. Mechanics in Engineering, 2022, 44(3): 491-502. [6] Department for Energy and Mining. Hydrogen in the gas distribution networks[R]. Australia: Government of South Australia, 2019. [7] Topolski K, Reznicek E, Erdener B, et al.Hydrogen blending into natural gas pipeline infrastructure: review of the state of technology[R]. USA: National Renewable Energy Laboratory (NREL), 2022. [8] 朱继忠, 骆腾燕, 吴皖莉, 等. 综合能源系统运行可靠性评估评述Ⅰ:模型驱动法[J]. 电工技术学报, 2022, 37(11): 2761-2776. Zhu Jizhong, Luo Tengyan, Wu Wanli, et al.A review of operational reliability assessment of integrated energy systems Ⅰ: model-driven method[J]. Transactions of China Electrotechnical Society, 2022, 37(11): 2761-2776. [9] 高鹏飞, 周孝信, 杨小煜, 等. 计及异质气体混合的电-气-热综合能源系统能量流计算方法[J]. 电网技术, 2021, 45(7): 2523-2533. Gao Pengfei, Zhou Xiaoxin, Yang Xiaoyu, et al.Energy flow calculation of integrated electricity, natural gas and heating systems considering mixtures of gas with alternative qualities[J]. Power System Technology, 2021, 45(7): 2523-2533. [10] 严思韵, 王晨, 周登极. 含氢能气网掺混输运的综合能源系统优化研究[J]. 电力工程技术, 2021, 40(1): 10-16, 49. Yan Siyun, Wang Chen, Zhou Dengji.Optimization of integrated electricity and gas system considering hydrogen-natural-gas mixture transportation[J]. Electric Power Engineering Technology, 2021, 40(1): 10-16, 49. [11] 黄雨佳, 孙秋野, 王睿, 等. 计及气体成分变化的电-气-热综合能源系统能量流计算方法[J]. 全球能源互联网, 2022, 5(6): 563-573. Huang Yujia, Sun Qiuye, Wang Rui, et al.Combined energy flow calculation method for electric-gas-heat integrated energy system considering gas composition changes[J]. Journal of Global Energy Interconnection, 2022, 5(6): 563-573. [12] 胡枭, 尚策, 程浩忠, 等. 综合能源系统能流计算方法述评与展望[J]. 电力系统自动化, 2020, 44(18): 179-191. Hu Xiao, Shang Ce, Cheng Haozhong, et al.Review and prospect of calculation method for energy flow in integrated energy system[J]. Automation of Electric Power Systems, 2020, 44(18): 179-191. [13] Qadrdan M, Abeysekera M, Chaudry M, et al.Role of power-to-gas in an integrated gas and electricity system in Great Britain[J]. International Journal of Hydrogen Energy, 2015, 40(17): 5763-5775. [14] Fu Chen, Lin Jin, Song Yonghua, et al.Optimal operation of an integrated energy system incorporated with HCNG distribution networks[J]. IEEE Transactions on Sustainable Energy, 2020, 11(4): 2141-2151. [15] Raheli E, Wu Qiuwei, Zhang Menglin, et al.Optimal coordinated operation of integrated natural gas and electric power systems: a review of modeling and solution methods[J]. Renewable and Sustainable Energy Reviews, 2021, 145: 111134. [16] Jia Wenlong, Ren Qingyang, Zhang Hao, et al.Multicomponent leakage and diffusion simulation of natural gas/hydrogen mixtures in compressor plants[J]. Safety Science, 2023, 157: 105916. [17] Li Zhuoran, Zhang Caigong, Li Changjun, et al.Thermodynamic evaluation of the effects of hydrogen blending on the Joule-Thomson characteristics of hydrogen-blended natural gas[J]. Journal of Cleaner Production, 2023, 406: 137074. [18] Elaoud S, Hafsi Z, Hadj-Taieb L.Numerical modelling of hydrogen-natural gas mixtures flows in looped networks[J]. Journal of Petroleum Science and Engineering, 2017, 159: 532-541. [19] Cristello J B, Yang J M, Hugo R, et al.Feasibility analysis of blending hydrogen into natural gas networks[J]. International Journal of Hydrogen Energy, 2023, 48(46): 17605-17629. [20] 邱玥, 周苏洋, 顾伟, 等. “碳达峰、碳中和”目标下混氢天然气技术应用前景分析[J]. 中国电机工程学报, 2022, 42(4): 1301-1321. Qiu Yue, Zhou Suyang, Gu Wei, et al.Application prospect analysis of hydrogen enriched compressed natural gas technologies under the target of carbon emission peak and carbon neutrality[J]. Proceedings of the CSEE, 2022, 42(4): 1301-1321. [21] Soave G.Equilibrium constants from a modified Redlich-Kwong equation of state[J]. Chemical Engineering Science, 1972, 27(6): 1197-1203. [22] 杨晓鸿, 朱薇玲. 粗糙度对输气管道摩阻系数的影响[J]. 石油化工设备, 2005, 34(1): 25-28. Yang Xiaohong, Zhu Weiling.The influence of inner surface roughness on the fiction factor of gas transmission pipeline[J]. Petro-Chemical Equipment, 2005, 34(1): 25-28. [23] 李长俊, 刘雨寒, 贾文龙. 多组分非理想气体扩散系数的改进[J]. 油气储运, 2019, 38(3): 297-302. Li Changjun, Liu Yuhan, Jia Wenlong.Modification of the diffusion coefficient of multi-component nonideal gas[J]. Oil & Gas Storage and Transportation, 2019, 38(3): 297-302. [24] Eames I, Austin M, Wojcik A.Injection of gaseous hydrogen into a natural gas pipeline[J]. International Journal of Hydrogen Energy, 2022, 47(61): 25745-25754. [25] 艾小猛, 方家琨, 徐沈智, 等. 一种考虑天然气系统动态过程的气电联合系统优化运行模型[J]. 电网技术, 2018, 42(2): 409-416. Ai Xiaomeng, Fang Jiakun, Xu Shenzhi, et al.An optimal energy flow model in integrated gas-electric systems considering dynamics of natural gas system[J]. Power System Technology, 2018, 42(2): 409-416. [26] 严铭卿. 燃气输配工程分析[M]. 北京: 石油工业出版社, 2007. [27] 陈彬彬, 孙宏斌, 陈瑜玮, 等. 综合能源系统分析的统一能路理论(一): 气路[J]. 中国电机工程学报, 2020, 40(2): 436-444. Chen Binbin, Sun Hongbin, Chen Yuwei, et al.Energy circuit theory of integrated energy system analysis (I): gaseous circuit[J]. Proceedings of the CSEE, 2020, 40(2): 436-444. [28] 严思韵, 周登极. 综合能源天然气网混氢输运的仿真与调度综述[J]. 中国电机工程学报, 2022, 42(24): 8816-8832. Yan Siyun, Zhou Dengji.Review of simulation and scheduling of hydrogen-blended transportation in natural gas network of integrated energy system[J]. Proceedings of the CSEE, 2022, 42(24): 8816-8832. [29] Zhang Zihang, Saedi I, Mhanna S, et al.Modelling of gas network transient flows with multiple hydrogen injections and gas composition tracking[J]. International Journal of Hydrogen Energy, 2022, 47(4): 2220-2233. [30] Deng Lirong, Sun Hongbin, Li Baoju, et al.Optimal operation of integrated heat and electricity systems: a tightening McCormick approach[J]. Engineering, 2021, 7(8): 1076-1086. [31] 李敬法, 苏越, 张衡, 等. 掺氢天然气管道输送研究进展[J]. 天然气工业, 2021, 41(4): 137-152. Li Jingfa, Su Yue, Zhang Heng, et al.Research progresses on pipeline transportation of hydrogen-blended natural gas[J]. Natural Gas Industry, 2021, 41(4): 137-152. [32] Fang Jiakun, Zeng Qing, Ai Xiaomeng, et al.Dynamic optimal energy flow in the integrated natural gas and electrical power systems[J]. IEEE Transactions on Sustainable Energy, 2018, 9(1): 188-198. [33] 陈彬彬, 孙宏斌, 吴文传, 等. 综合能源系统分析的统一能路理论(三):稳态与动态潮流计算[J]. 中国电机工程学报, 2020, 40(15): 4820-4831. Chen Binbin, Sun Hongbin, Wu Wenchuan, et al.Energy circuit theory of integrated energy system analysis(Ⅲ): steady and dynamic energy flow calculation[J]. Proceedings of the CSEE, 2020, 40(15): 4820-4831. [34] Yang Jingwei, Zhang Ning, Kang Chongqing, et al.Effect of natural gas flow dynamics in robust generation scheduling under wind uncertainty[J]. IEEE Transactions on Power Systems, 2018, 33(2): 2087-2097. [35] 李佳蓉, 林今, 邢学韬, 等. 主动配电网中基于统一运行模型的电制氢(P2H)模块组合选型与优化规划[J]. 中国电机工程学报, 2021, 41(12): 4021-4032. Li Jiarong, Lin Jin, Xing Xuetao, et al.Technology portfolio selection and optimal planning of power-to-hydrogen (P2H) modules in active distribution network[J]. Proceedings of the CSEE, 2021, 41(12): 4021-4032. [36] 黄明, 吴勇, 文习之, 等. 利用天然气管道掺混输送氢气的可行性分析[J]. 煤气与热力, 2013, 33(4): 39-42. Huang Ming, Wu Yong, Wen Xizhi, et al.Feasibility analysis of hydrogen transport in natural gas pipeline[J]. Gas & Heat, 2013, 33(4): 39-42. [37] 齐世雄, 王秀丽, 邵成成, 等. 极端事件下电-气混联综合能源系统的恢复力分析[J]. 电网技术, 2019, 43(1): 41-51. Qi Shixiong, Wang Xiuli, Shao Chengcheng, et al.Resilience analysis of integrated electricity and natural gas energy system under extreme events[J]. Power System Technology, 2019, 43(1): 41-51. [38] 翟江, 周孝信, 李亚楼, 等. 综合能源系统天然气管道压力和流量的控制方案研究[J]. 中国电机工程学报, 2022, 42(11): 3911-3924. Zhai Jiang, Zhou Xiaoxin, Li Yalou, et al.Research on control strategy of pressure and flow of natural gas pipeline in integrated energy system[J]. Proceedings of the CSEE, 2022, 42(11): 3911-3924. [39] 陈红坤, 王雪纯, 陈磊. 考虑灵活性供给约束的区域综合能源系统节点边际能价分解分析[J]. 电工技术学报, 2023, 38(13): 3576-3589. Chen Hongkun, Wang Xuechun, Chen Lei.Decomposition analysis on locational marginal energy prices in regional integrated energy system considering flexibility provision constraints[J]. Transactions of China Electrotechnical Society, 2023, 38(13): 3576-3589.
2023, Vol. 38 
