Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid

Cold energy generation is an important part of liquefied natural gas (LNG) cold energy cascade utilization, and existing studies lack a specific descriptive model for LNG cold energy transmission to the AC subgrid. Therefore, this paper proposes a descriptive model for the grid-connected process of...

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Main Authors: Yu Qi, Pengliang Zuo, Rongzhao Lu, Dongxu Wang, Yingjun Guo
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/17/21/5323
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author Yu Qi
Pengliang Zuo
Rongzhao Lu
Dongxu Wang
Yingjun Guo
author_facet Yu Qi
Pengliang Zuo
Rongzhao Lu
Dongxu Wang
Yingjun Guo
author_sort Yu Qi
collection DOAJ
description Cold energy generation is an important part of liquefied natural gas (LNG) cold energy cascade utilization, and existing studies lack a specific descriptive model for LNG cold energy transmission to the AC subgrid. Therefore, this paper proposes a descriptive model for the grid-connected process of cold energy generation at LNG stations. First, the expansion kinetic energy transfer of the intermediate work mass is derived and analyzed in the LNG unipolar Rankine cycle structure, the mathematical relationship between the turbine output mechanical power and the variation in the work mass flow rate and pressure is established, and the variations in the LNG heat exchanger temperature difference, seawater flow rate, and the turbine temperature difference in the cycle system are investigated. Secondly, based on the fifth-order equation of state of the synchronous generator, the expressions of its electromagnetic power, output AC frequency, and voltage were analyzed. Finally, the average equivalent models of the machine-side and grid-side converters are established using a direct-fed grid-connected structure, thus forming a descriptive model of the overall drive process. The ORC model is built in Aspen HYSIS to obtain the time series expression of the torque output of the turbine; based on the ORC output torque, the permanent magnet synchronous generator (PMGSG) as well as the direct-fed grid-connected structure are built in MATLAB/Simulink, and the active power and current outputs of the grid-following-type voltage vector control method and the grid-forming-type power-angle synchronous control method are also verified.
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spelling doaj-art-3ed92938e64d474a9a3332fd0778e49e2024-11-08T14:35:18ZengMDPI AGEnergies1996-10732024-10-011721532310.3390/en17215323Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution GridYu Qi0Pengliang Zuo1Rongzhao Lu2Dongxu Wang3Yingjun Guo4School of Electric Engineering, Hebei University of Science and Technology, Shijiazhuang 050027, ChinaCaofeidian Xintian LNG Co., Ltd., Tangshan 063200, ChinaCaofeidian Xintian LNG Co., Ltd., Tangshan 063200, ChinaCaofeidian Xintian LNG Co., Ltd., Tangshan 063200, ChinaSchool of Electric Engineering, Hebei University of Science and Technology, Shijiazhuang 050027, ChinaCold energy generation is an important part of liquefied natural gas (LNG) cold energy cascade utilization, and existing studies lack a specific descriptive model for LNG cold energy transmission to the AC subgrid. Therefore, this paper proposes a descriptive model for the grid-connected process of cold energy generation at LNG stations. First, the expansion kinetic energy transfer of the intermediate work mass is derived and analyzed in the LNG unipolar Rankine cycle structure, the mathematical relationship between the turbine output mechanical power and the variation in the work mass flow rate and pressure is established, and the variations in the LNG heat exchanger temperature difference, seawater flow rate, and the turbine temperature difference in the cycle system are investigated. Secondly, based on the fifth-order equation of state of the synchronous generator, the expressions of its electromagnetic power, output AC frequency, and voltage were analyzed. Finally, the average equivalent models of the machine-side and grid-side converters are established using a direct-fed grid-connected structure, thus forming a descriptive model of the overall drive process. The ORC model is built in Aspen HYSIS to obtain the time series expression of the torque output of the turbine; based on the ORC output torque, the permanent magnet synchronous generator (PMGSG) as well as the direct-fed grid-connected structure are built in MATLAB/Simulink, and the active power and current outputs of the grid-following-type voltage vector control method and the grid-forming-type power-angle synchronous control method are also verified.https://www.mdpi.com/1996-1073/17/21/5323liquefied natural gascold energy generationorganic Rankine cycleenergy drive modelinggrid-connected converter
spellingShingle Yu Qi
Pengliang Zuo
Rongzhao Lu
Dongxu Wang
Yingjun Guo
Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
Energies
liquefied natural gas
cold energy generation
organic Rankine cycle
energy drive modeling
grid-connected converter
title Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
title_full Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
title_fullStr Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
title_full_unstemmed Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
title_short Modeling of Liquefied Natural Gas Cold Power Generation for Access to the Distribution Grid
title_sort modeling of liquefied natural gas cold power generation for access to the distribution grid
topic liquefied natural gas
cold energy generation
organic Rankine cycle
energy drive modeling
grid-connected converter
url https://www.mdpi.com/1996-1073/17/21/5323
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