This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mod...This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mode Control(GFISMC)is proposed based on the tip speed ratio method and sliding mode control.The algorithm uses fast integral sliding mode surface and fuzzy fast switching control items to ensure that the offshore wind power generation system can track the maximum power point quickly and with low jitter.An offshore wind power generation system model is presented to verify the algorithm effect.An offshore off-grid wind-solar hybrid power generation systemis built in MATLAB/Simulink.Compared with other MPPT algorithms,this study has specific quantitative improvements in terms of convergence speed,tracking accuracy or computational efficiency.Finally,the improved algorithm is further analyzed and carried out by using Yuankuan Energy’s ModelingTech semi-physical simulation platform.The results verify the feasibility and effectiveness of the improved algorithm in the offshore wind-solar hybrid power generation system.展开更多
The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,th...The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector.In this study,a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry,called the SSM-Cement framework,is proposed.The framework comprises four main modules:the cement plant suitability screening module,the storage site assessment module,the source–sink matching optimization model module,and the economic assessment module.By applying this framework to China,919 candidates are initially screened from 1132 existing cement plants.Further,603 CCUS-ready cement plants are identified,and are found to achieve a cumulative emission reduction of 18.5 Gt CO_(2) from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO_(2) transportation routes.The levelized cost of cement(LCOC)is found to range from 30 to 96(mean 73)USD·(t cement)^(-1),while the levelized carbon avoidance cost(LCAC)ranges from^(-5) to 140(mean 88)USD·(t CO_(2))^(-1).The northeastern and northwestern regions of China are considered priority areas for CCUS implementation,with the LCAC concentrated in the range of 35 to 70 USD·(t CO_(2))^(-1).In addition to onshore storage of 15.8 Gt CO_(2) from 2030 to 2060,offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants,with comparable LCACs around 90 USD·(t CO_(2))^(-1).展开更多
This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the A...This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the Absolute Nodal Coordinate Formulation(ANCF)and a spatial-temporal density variation equation to analyze how slug flow parameters affect the SIV response of risers.Structural displacement,stress,and fatigue responses are systematically evaluated to characterize the structural behavior under SIV conditions.Longer slugs induce more pronounced traveling wave characteristics,while shorter slugs facilitate a mixed traveling-standing wave mode.Moreover,higher slug frequencies lead to increased fatigue accumulation,especially over an extended touchdown zone,thereby compromising the structural integrity of the riser.The findings yield valuable insights into the dynamic interactions between slug flow and riser response.This research advances the understanding of SIV mechanisms and provides a theoretical foundation for fatigue assessment and structural optimization,contributing to the safe and efficient design of offshore risers in deepwater environments.展开更多
At the"Deep Sea New Offshore Equipment Development Forum"held during the 2025 Nantong Shipbuilding and Offshore Engineering Industry Exhibition,industry experts and enterprise representatives conducted in-de...At the"Deep Sea New Offshore Equipment Development Forum"held during the 2025 Nantong Shipbuilding and Offshore Engineering Industry Exhibition,industry experts and enterprise representatives conducted in-depth exchanges on key topics such as technological innovation and industrial chain synergy in the offshore equipment industry,offshore oil and gas development market trends,green and low-carbon technology development,and deep-sea equipment,providing an important reference for the future development path of the offshore equipment industry.The vips said that at present,although the offshore equipment market is facing short-term fluctuations,its long-term potential is highlighted,and the green and intelligent transformation is injecting strong new momentum into the development of the industry.展开更多
Anomaly detection in wind turbines involves emphasizing its ability to improve operational efficiency,reduce maintenance costs,extend their lifespan,and enhance reliability in the wind energy sector.This is particular...Anomaly detection in wind turbines involves emphasizing its ability to improve operational efficiency,reduce maintenance costs,extend their lifespan,and enhance reliability in the wind energy sector.This is particularly necessary in offshore wind,currently one of the most critical assets for achieving sustainable energy generation goals,due to the harsh marine environment and the difficulty of maintenance tasks.To address this problem,this work proposes a data-driven methodology for detecting power generation anomalies in offshore wind turbines,using normalized and linearized operational data.The proposed framework transforms heterogeneous wind speed and power measurements into a unified scale,enabling the development of a new wind power index(WPi)that quantifies deviations from expected performance.Additionally,spatial and temporal coherence analyses of turbines within a wind farm ensure the validity of these normalized measurements across different wind turbine models and operating conditions.Furthermore,a Support Vector Machine(SVM)refines the classification process,effectively distinguishing measurement errors from actual power generation failures.Validation of this strategy using real-world data from the Alpha Ventus wind farm demonstrates that the proposed approach not only improves predictive maintenance but also optimizes energy production,highlighting its potential for broad application in offshore wind installations.展开更多
The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as sour...The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.展开更多
The novel structural reliability methodology presented in this study is especially well suited for multidimensional structural dynamics that are physically measured or numerically simulated over a representative timel...The novel structural reliability methodology presented in this study is especially well suited for multidimensional structural dynamics that are physically measured or numerically simulated over a representative timelapse.The Gaidai multivariate reliability method is applied to an operational offshore Jacket platform that operates in Bohai Bay.This study demonstrates the feasibility of this method to accurately estimate collapse risks in dynamic systems under in situ environmental stressors.Modern reliability approaches do not cope easily with the high dimensionality of real engineering dynamic systems,as well as nonlinear intercorrelations between various structural components.The Jacket offshore platform is chosen as the case study for this reliability analysis because of the presence of various hotspot stresses that synchronously arise in its structural parts.The authors provide a straightforward,precise method for estimating overall risks of operational failure,damage,or hazard for nonlinear multidimensional dynamic systems.The latter tool is important for offshore engineers during the design stage.展开更多
Offshore platforms are large,complex structures designed for long-term service,and they are characterized by high risk and significant investment.Ensuring the safety and reliability of in-service offshore platforms re...Offshore platforms are large,complex structures designed for long-term service,and they are characterized by high risk and significant investment.Ensuring the safety and reliability of in-service offshore platforms requires intelligent operation and maintenance strategies.Digital twin technology can enable the accurate description and prediction of changes in the platform’s physical state through real-time monitoring data.This technology is expected to revolutionize the maintenance of existing offshore platform structures.A digital twin system is proposed for real-time assessment of structural health,prediction of residual life,formulation of maintenance plans,and extension of service life through predictive maintenance.The system integrates physical entities,digital models,intelligent predictive maintenance tools,a visualization platform,and interconnected modules to provide a comprehensive and efficient maintenance framework.This paper examines the current development status of core technologies in physical entity monitoring,digital model construction,and intelligent predictive maintenance.It also outlines future directions for the advancement of these technologies within the digital twin system,offering technical insights and practical references to support further research and applications of digital twin technology in offshore platform structures.展开更多
To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground moti...To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.展开更多
The jacket structure and transition piece comprise the supporting structure of a bottom-fixed offshore wind turbine(OWT)connected to the steel tower,which determines the overall structural dynamic performance of the e...The jacket structure and transition piece comprise the supporting structure of a bottom-fixed offshore wind turbine(OWT)connected to the steel tower,which determines the overall structural dynamic performance of the entire OWT.Ideally,optimal performance can be realized by effectively coordinating two components,notwithstanding their separate design processes.In pursuit of this objective,this paper proposes a concurrent design methodology for the jacket structure and transition piece by exploiting topology optimization(TO).The TO for a three-legged jacket foundation is formulated by minimizing static compliance.In contrast to conventional TO,two separated volume fractions are imposed upon the structural design domain of the jacket structure and transition piece to ensure continuity.A 5 MW(megawatt)OWT supported by a four-legged or three-legged jacket substructure is under investigation.The external loads are derived from various design load cases that are acquired using the commercial software platform DNV Bladed(Det Norske Veritas).Through a comparative analysis of the fundamental frequency and maximum nodal deformation,it was found that the optimized solution demonstrates a reduced weight and superior stiffness.The findings demonstrate the present concurrent design approach using TO can yield significant benefits by reducing the overall design cycle and enhancing the feasibility of the final design.展开更多
Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experi...Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.展开更多
The rapid expansion of offshore wind energy necessitates robust and cost-effective electrical collector system(ECS)designs that prioritize lifetime operational reliability.Traditional optimization approaches often sim...The rapid expansion of offshore wind energy necessitates robust and cost-effective electrical collector system(ECS)designs that prioritize lifetime operational reliability.Traditional optimization approaches often simplify reliability considerations or fail to holistically integrate them with economic and technical constraints.This paper introduces a novel,two-stage optimization framework for offshore wind farm(OWF)ECS planning that systematically incorporates reliability.The first stage employs Mixed-Integer Linear Programming(MILP)to determine an optimal radial network topology,considering linearized reliability approximations and geographical constraints.The second stage enhances this design by strategically placing tie-lines using a Mixed-Integer Quadratically Constrained Program(MIQCP).This stage leverages a dynamic-aware adaptation of Multi-Source Multi-Terminal Network Reliability(MSMT-NR)assessment,with its inherent nonlinear equations successfully transformed into a solvable MIQCP form for loopy networks.A benchmark case study demonstrates the framework’s efficacy,illustrating how increasing the emphasis on reliability leads to more distributed and interconnected network topologies,effectively balancing investment costs against enhanced system resilience.展开更多
In offshore maritime communication sys-tems,base stations(BSs)are employed along the coastline to provide high-speed data service for ves-sels in coastal sea areas.To ensure the line-of-sight propagation of BS-vessel ...In offshore maritime communication sys-tems,base stations(BSs)are employed along the coastline to provide high-speed data service for ves-sels in coastal sea areas.To ensure the line-of-sight propagation of BS-vessel links,high transceiver an-tenna height is required,which limits the number of geographically available sites for BS deployment,and imposes a high cost for realizing effective wide-area coverage.In this paper,the joint user association and power allocation(JUAPA)problem is investigated to enhance the coverage of offshore maritime systems.By exploiting the characteristics of network topology as well as vessels’motion in offshore communica-tions,a multi-period JUAPA problem is formulated to maximize the number of ships that can be simultane-ously served by the network.This JUAPA problem is intrinsically non-convex and subject to mixed-integer constraints,which is difficult to solve either analyt-ically or numerically.Hence,we propose an iterative augmentation based framework to efficiently select the active vessels,where the JUAPA scheme is iteratively optimized by the network for increasing the number of the selected vessels.More specifically,in each itera-tion,the user association variables and power alloca-tion variables are determined by solving two separate subproblems,so that the JUAPA strategy can be up-dated in a low-complexity manner.The performance of the proposed JUAPA method is evaluated by exten-sive simulation,and numerical results indicate that it can effectively increase the number of vessels served by the network,and thus enhances the coverage of off-shore systems.展开更多
Fracture conductivity is a key factor to determine the fracturing effect.Optimizing proppant particle size distribution is critical for ensuring efficient proppant placement within fractures.To address challenges asso...Fracture conductivity is a key factor to determine the fracturing effect.Optimizing proppant particle size distribution is critical for ensuring efficient proppant placement within fractures.To address challenges associated with the low-permeability reservoirs in the Lufeng Oilfield of the South China Sea—including high heterogeneity,complex lithology,and suboptimal fracturing outcomes—JRC(Joint Roughness Coefficient)was employed to quantitatively characterize the lithological properties of the target formation.A CFD-DEM(Computational Fluid Dynamics-Discrete Element Method)two-way coupling approach was then utilized to construct a fracture channel model that simulates proppant transport dynamics.Theproppant particle size under different lithology was optimized.Theresults show that:(1)In rough fractures,proppant particles exhibit more chaotic migration behavior compared to their movement on smooth surfaces,thereby increasing the risk of fracture plugging;(2)Within the same particle size range,for proppants with mesh sizes of 40/70 or 20/40,fracture conductivity decreases as roughness increases.In contrast,for 30/50 mesh proppants,conductivity initially increases and then decreases with rising roughness;(3)Under identical roughness conditions,the following recommendations apply based on fracture conductivity behavior relative to proppant particle size:When JRC<46,conductivity increases with larger particle sizes,with 20/40 mesh proppant recommended;When JRC>46,conductivity decreases as particle size increases;40/70 mesh proppant is thus recommended to maintain effective conductivity;At JRC=46,conductivity first increases then decreases with increasing particle size,making 30/50mesh the optimal choice.Theresearch findings provide a theoretical foundation for optimizing fracturing designs and enhancing fracturing performance in the field.展开更多
Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experim...Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.展开更多
With the rapid advancement of offshore wind power and the increasing scarcity of nearshore site resources,the development of offshore wind energy is inevitably moving towards deep seas.Floating offshore wind power tec...With the rapid advancement of offshore wind power and the increasing scarcity of nearshore site resources,the development of offshore wind energy is inevitably moving towards deep seas.Floating offshore wind power technology is considered the primary technology for future offshore wind power development in deep seas.展开更多
This study employed a computational fluid dynamics model with an overset mesh technique to investigate the thrust and power of a floating offshore wind turbine(FOWT)under platform floating motion in the wind–rain fie...This study employed a computational fluid dynamics model with an overset mesh technique to investigate the thrust and power of a floating offshore wind turbine(FOWT)under platform floating motion in the wind–rain field.The impact of rainfall on aerodynamic performance was initially examined using a stationary turbine model in both wind and wind–rain conditions.Subsequently,the study compared the FOWT’s performance under various single degree-of-freedom(DOF)motions,including surge,pitch,heave,and yaw.Finally,the combined effects of wind–rain fields and platform motions involving two DOFs on the FOWT’s aerodynamics were analyzed and compared.The results demonstrate that rain negatively impacts the aerodynamic performance of both the stationary turbines and FOWTs.Pitch-dominated motions,whether involving single or multiple DOFs,caused significant fluctuations in the FOWT aerodynamics.The combination of surge and pitch motions created the most challenging operational environment for the FOWT in all tested scenarios.These findings highlighted the need for stronger construction materials and greater ultimate bearing capacity for FOWTs,as well as the importance of optimizing designs to mitigate excessive pitch and surge.展开更多
The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir....The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir.The reuse plan involves removing outdated equipment from the platform’s decks while retaining essential components such as wellheads and separators.Exploiting a depleted reservoir for the injection of an H_(2)-CH_(4) mixture requires a thorough understanding of its specific characteristics.This paper focuses on the engineering approach adopted in the basic design phase for such a conversion,providing recommendations and HSE guidelines.Given the hazardous nature of substances like hydrogen in the gas mixture,the paper also examines potential risk scenarios,particularly those involving containment loss.A qualitative and quantitative assessment of these risks is conducted to evaluate their impact on the structure and equipment.The results of this assessment serve as a foundation for later studies on layout optimization and domino effect prevention.Additionally,some critical scenarios are simulated using an innovative approach known as the Source Box Accident Model(SBAM),which was proposed in previous works.SBAM leverages Computational Fluid Dynamics(CFD)but decouples the accidental phenomenon into a release phase and a dispersion phase.This method overcomes the challenges conventional CFD tools face in assessing congested plant configurations,providing more precise estimations of gas cloud behavior.The simulation results indicate that the released gas remains within the platform deck domain,and the flammable cloud is significantly smaller than what traditional,simplified tools predict.展开更多
Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,w...Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,we applied machine learning techniques to obtain hydrodynamic and aerodynamic loads of FOWTs by measuring platform motion responses and wave-elevation sequences.First,a computational fluid dynamics(CFD)simulation model of the floating platform was established based on the dynamic fluid body interaction technique and overset grid technology.Then,a long short-term memory(LSTM)neural network model was constructed and trained to learn the nonlinear relationship between the waves,platform-motion inputs,and hydrodynamic-load outputs.The optimal model was determined after analyzing the sensitivity of parameters such as sample characteristics,network layers,and neuron numbers.Subsequently,the effectiveness of the hydrodynamic load model was validated under different simulation conditions,and the aerodynamic load calculation was completed based on the D'Alembert principle.Finally,we built a hybrid-scale FOWT model,based on the software in the loop strategy,in which the wind turbine was replaced by an actuation system.Model tests were carried out in a wave basin and the results demonstrated that the root mean square errors of the hydrodynamic and aerodynamic load measurements were 4.20%and 10.68%,respectively.展开更多
Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atm...Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atmospheric Administration)CRW(Coral Reef Watch)daily mean sea surface temperature dataset spanning from 1985 to 2022 to comprehensively analyze the fundamental attributes and evolving patterns of marine heatwaves in the offshore waters of China.Eight pronounced marine heatwaves from frequently affected sensitive regions were investigated to explore their formation mechanisms.The relationship between the occurrences of marine heatwave and large-scale climate mode in the region was explored.Results show that the western Pacific subtropical high plays an essential role in triggering marine heatwaves in Chinese offshore waters,with an anomalous downward shortwave radiation flux acting to warm the sea surface,which is remotely associated to the large-scale sea surface temperature state.Distinct mechanisms for the MHWs were identified in the northern and southern offshore waters of China.MHWs in high latitudes(such as the Bohai Sea and the Yellow Sea)mainly occur during the negative phase of the Pacific Decadal Oscillation(PDO),while those in low latitudes(such as the South China Sea)are more common in about 5-month lags behind the El Niño,for which we purposed a mechanism to describe the main differences in the formation of MHWs in China and discussed the related implications.展开更多
基金supported by the 2022 Sanya Science and Technology Innovation Project,China(No.2022KJCX03)the Sanya Science and Education Innovation Park,Wuhan University of Technology,China(Grant No.2022KF0028)the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City,China(Grant No.2021JJLH0036).
文摘This study investigates the Maximum Power Point Tracking(MPPT)control method of offshore windphotovoltaic hybrid power generation system with offshore crane-assisted.A new algorithm of Global Fast Integral Sliding Mode Control(GFISMC)is proposed based on the tip speed ratio method and sliding mode control.The algorithm uses fast integral sliding mode surface and fuzzy fast switching control items to ensure that the offshore wind power generation system can track the maximum power point quickly and with low jitter.An offshore wind power generation system model is presented to verify the algorithm effect.An offshore off-grid wind-solar hybrid power generation systemis built in MATLAB/Simulink.Compared with other MPPT algorithms,this study has specific quantitative improvements in terms of convergence speed,tracking accuracy or computational efficiency.Finally,the improved algorithm is further analyzed and carried out by using Yuankuan Energy’s ModelingTech semi-physical simulation platform.The results verify the feasibility and effectiveness of the improved algorithm in the offshore wind-solar hybrid power generation system.
基金financial support of National Natural Science Foundation of China(72174196 and 71874193)the Open Fund of State Key Laboratory of Coal Resources and Safe Mining(SKLCRSM21KFA05)National Program for Support of Top-Notch Young Professionals.
文摘The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector.In this study,a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry,called the SSM-Cement framework,is proposed.The framework comprises four main modules:the cement plant suitability screening module,the storage site assessment module,the source–sink matching optimization model module,and the economic assessment module.By applying this framework to China,919 candidates are initially screened from 1132 existing cement plants.Further,603 CCUS-ready cement plants are identified,and are found to achieve a cumulative emission reduction of 18.5 Gt CO_(2) from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO_(2) transportation routes.The levelized cost of cement(LCOC)is found to range from 30 to 96(mean 73)USD·(t cement)^(-1),while the levelized carbon avoidance cost(LCAC)ranges from^(-5) to 140(mean 88)USD·(t CO_(2))^(-1).The northeastern and northwestern regions of China are considered priority areas for CCUS implementation,with the LCAC concentrated in the range of 35 to 70 USD·(t CO_(2))^(-1).In addition to onshore storage of 15.8 Gt CO_(2) from 2030 to 2060,offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants,with comparable LCACs around 90 USD·(t CO_(2))^(-1).
基金financially supported by the National Natural Science Foundation of China(Grant No.52222111)the Science Foundation of China University of Petroleum,Beijing(Grant No.2462025SZBH002)。
文摘This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the Absolute Nodal Coordinate Formulation(ANCF)and a spatial-temporal density variation equation to analyze how slug flow parameters affect the SIV response of risers.Structural displacement,stress,and fatigue responses are systematically evaluated to characterize the structural behavior under SIV conditions.Longer slugs induce more pronounced traveling wave characteristics,while shorter slugs facilitate a mixed traveling-standing wave mode.Moreover,higher slug frequencies lead to increased fatigue accumulation,especially over an extended touchdown zone,thereby compromising the structural integrity of the riser.The findings yield valuable insights into the dynamic interactions between slug flow and riser response.This research advances the understanding of SIV mechanisms and provides a theoretical foundation for fatigue assessment and structural optimization,contributing to the safe and efficient design of offshore risers in deepwater environments.
文摘At the"Deep Sea New Offshore Equipment Development Forum"held during the 2025 Nantong Shipbuilding and Offshore Engineering Industry Exhibition,industry experts and enterprise representatives conducted in-depth exchanges on key topics such as technological innovation and industrial chain synergy in the offshore equipment industry,offshore oil and gas development market trends,green and low-carbon technology development,and deep-sea equipment,providing an important reference for the future development path of the offshore equipment industry.The vips said that at present,although the offshore equipment market is facing short-term fluctuations,its long-term potential is highlighted,and the green and intelligent transformation is injecting strong new momentum into the development of the industry.
基金supported by the Spanish Ministry of Science and Innovation under the MCI/AEI/FEDER project number PID2021-123543OBC21.
文摘Anomaly detection in wind turbines involves emphasizing its ability to improve operational efficiency,reduce maintenance costs,extend their lifespan,and enhance reliability in the wind energy sector.This is particularly necessary in offshore wind,currently one of the most critical assets for achieving sustainable energy generation goals,due to the harsh marine environment and the difficulty of maintenance tasks.To address this problem,this work proposes a data-driven methodology for detecting power generation anomalies in offshore wind turbines,using normalized and linearized operational data.The proposed framework transforms heterogeneous wind speed and power measurements into a unified scale,enabling the development of a new wind power index(WPi)that quantifies deviations from expected performance.Additionally,spatial and temporal coherence analyses of turbines within a wind farm ensure the validity of these normalized measurements across different wind turbine models and operating conditions.Furthermore,a Support Vector Machine(SVM)refines the classification process,effectively distinguishing measurement errors from actual power generation failures.Validation of this strategy using real-world data from the Alpha Ventus wind farm demonstrates that the proposed approach not only improves predictive maintenance but also optimizes energy production,highlighting its potential for broad application in offshore wind installations.
文摘The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.
文摘The novel structural reliability methodology presented in this study is especially well suited for multidimensional structural dynamics that are physically measured or numerically simulated over a representative timelapse.The Gaidai multivariate reliability method is applied to an operational offshore Jacket platform that operates in Bohai Bay.This study demonstrates the feasibility of this method to accurately estimate collapse risks in dynamic systems under in situ environmental stressors.Modern reliability approaches do not cope easily with the high dimensionality of real engineering dynamic systems,as well as nonlinear intercorrelations between various structural components.The Jacket offshore platform is chosen as the case study for this reliability analysis because of the presence of various hotspot stresses that synchronously arise in its structural parts.The authors provide a straightforward,precise method for estimating overall risks of operational failure,damage,or hazard for nonlinear multidimensional dynamic systems.The latter tool is important for offshore engineers during the design stage.
基金Supported by the National Natural Science Foundation of China under Grant No.11472076Heilongjiang Provincial Universities Basic Scientific Research Business Fee Research Project No.145209210.
文摘Offshore platforms are large,complex structures designed for long-term service,and they are characterized by high risk and significant investment.Ensuring the safety and reliability of in-service offshore platforms requires intelligent operation and maintenance strategies.Digital twin technology can enable the accurate description and prediction of changes in the platform’s physical state through real-time monitoring data.This technology is expected to revolutionize the maintenance of existing offshore platform structures.A digital twin system is proposed for real-time assessment of structural health,prediction of residual life,formulation of maintenance plans,and extension of service life through predictive maintenance.The system integrates physical entities,digital models,intelligent predictive maintenance tools,a visualization platform,and interconnected modules to provide a comprehensive and efficient maintenance framework.This paper examines the current development status of core technologies in physical entity monitoring,digital model construction,and intelligent predictive maintenance.It also outlines future directions for the advancement of these technologies within the digital twin system,offering technical insights and practical references to support further research and applications of digital twin technology in offshore platform structures.
基金National Natural Science Foundation of China under Grant No.52478568National Key R&D Program of China under Grant Nos.2021YFC3100701 and 2022YFC3003503the Nature Science Foundation of Hubei Province under Grant No.2023AFA030。
文摘To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.
基金supports were received from the National Key Research and Development Program of China(2024YFE0208600)New Energy Joint Laboratory of China Southern Power Grid Corporation(GDXNY2024KF03)+2 种基金the National Natural Science Foundation of China(Grant No.U24B2090)National Key R&D Program(No.2022YFB4201300)Science and Technology Project of Huaneng Group(HNKJ24-H78).
文摘The jacket structure and transition piece comprise the supporting structure of a bottom-fixed offshore wind turbine(OWT)connected to the steel tower,which determines the overall structural dynamic performance of the entire OWT.Ideally,optimal performance can be realized by effectively coordinating two components,notwithstanding their separate design processes.In pursuit of this objective,this paper proposes a concurrent design methodology for the jacket structure and transition piece by exploiting topology optimization(TO).The TO for a three-legged jacket foundation is formulated by minimizing static compliance.In contrast to conventional TO,two separated volume fractions are imposed upon the structural design domain of the jacket structure and transition piece to ensure continuity.A 5 MW(megawatt)OWT supported by a four-legged or three-legged jacket substructure is under investigation.The external loads are derived from various design load cases that are acquired using the commercial software platform DNV Bladed(Det Norske Veritas).Through a comparative analysis of the fundamental frequency and maximum nodal deformation,it was found that the optimized solution demonstrates a reduced weight and superior stiffness.The findings demonstrate the present concurrent design approach using TO can yield significant benefits by reducing the overall design cycle and enhancing the feasibility of the final design.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2021YFB2601100)the National Natural Science Foundation of China (Grant No. 51979190)。
文摘Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
基金supported by the Science and Technology Project of China South Power Grid Co.,Ltd.,Grant Nos.036000KK52222044,GDKJXM20222430。
文摘The rapid expansion of offshore wind energy necessitates robust and cost-effective electrical collector system(ECS)designs that prioritize lifetime operational reliability.Traditional optimization approaches often simplify reliability considerations or fail to holistically integrate them with economic and technical constraints.This paper introduces a novel,two-stage optimization framework for offshore wind farm(OWF)ECS planning that systematically incorporates reliability.The first stage employs Mixed-Integer Linear Programming(MILP)to determine an optimal radial network topology,considering linearized reliability approximations and geographical constraints.The second stage enhances this design by strategically placing tie-lines using a Mixed-Integer Quadratically Constrained Program(MIQCP).This stage leverages a dynamic-aware adaptation of Multi-Source Multi-Terminal Network Reliability(MSMT-NR)assessment,with its inherent nonlinear equations successfully transformed into a solvable MIQCP form for loopy networks.A benchmark case study demonstrates the framework’s efficacy,illustrating how increasing the emphasis on reliability leads to more distributed and interconnected network topologies,effectively balancing investment costs against enhanced system resilience.
基金supported by the National Key Research and Development Program of China under Grant 2018YFA0701601by the Program of Jiangsu Province under Grant NTACT-2024-Z-001.
文摘In offshore maritime communication sys-tems,base stations(BSs)are employed along the coastline to provide high-speed data service for ves-sels in coastal sea areas.To ensure the line-of-sight propagation of BS-vessel links,high transceiver an-tenna height is required,which limits the number of geographically available sites for BS deployment,and imposes a high cost for realizing effective wide-area coverage.In this paper,the joint user association and power allocation(JUAPA)problem is investigated to enhance the coverage of offshore maritime systems.By exploiting the characteristics of network topology as well as vessels’motion in offshore communica-tions,a multi-period JUAPA problem is formulated to maximize the number of ships that can be simultane-ously served by the network.This JUAPA problem is intrinsically non-convex and subject to mixed-integer constraints,which is difficult to solve either analyt-ically or numerically.Hence,we propose an iterative augmentation based framework to efficiently select the active vessels,where the JUAPA scheme is iteratively optimized by the network for increasing the number of the selected vessels.More specifically,in each itera-tion,the user association variables and power alloca-tion variables are determined by solving two separate subproblems,so that the JUAPA strategy can be up-dated in a low-complexity manner.The performance of the proposed JUAPA method is evaluated by exten-sive simulation,and numerical results indicate that it can effectively increase the number of vessels served by the network,and thus enhances the coverage of off-shore systems.
基金funded by China NationalOffshore Oil Corporation(CNOOC)14th Five-Year Plan Major Science and Technology Project:Research on Integrated Geological Engineering Technology for Fracturing and Development of Offshore Low-Permeability Reservoirs(Grant NO.KJGG2022-0701).Mao Jiang,Chengyong Peng,JiangshuWu and Xuesong Xing.https://www.cnooc.com.cn.
文摘Fracture conductivity is a key factor to determine the fracturing effect.Optimizing proppant particle size distribution is critical for ensuring efficient proppant placement within fractures.To address challenges associated with the low-permeability reservoirs in the Lufeng Oilfield of the South China Sea—including high heterogeneity,complex lithology,and suboptimal fracturing outcomes—JRC(Joint Roughness Coefficient)was employed to quantitatively characterize the lithological properties of the target formation.A CFD-DEM(Computational Fluid Dynamics-Discrete Element Method)two-way coupling approach was then utilized to construct a fracture channel model that simulates proppant transport dynamics.Theproppant particle size under different lithology was optimized.Theresults show that:(1)In rough fractures,proppant particles exhibit more chaotic migration behavior compared to their movement on smooth surfaces,thereby increasing the risk of fracture plugging;(2)Within the same particle size range,for proppants with mesh sizes of 40/70 or 20/40,fracture conductivity decreases as roughness increases.In contrast,for 30/50 mesh proppants,conductivity initially increases and then decreases with rising roughness;(3)Under identical roughness conditions,the following recommendations apply based on fracture conductivity behavior relative to proppant particle size:When JRC<46,conductivity increases with larger particle sizes,with 20/40 mesh proppant recommended;When JRC>46,conductivity decreases as particle size increases;40/70 mesh proppant is thus recommended to maintain effective conductivity;At JRC=46,conductivity first increases then decreases with increasing particle size,making 30/50mesh the optimal choice.Theresearch findings provide a theoretical foundation for optimizing fracturing designs and enhancing fracturing performance in the field.
基金The National Natural Science Foundation of China(No.52171274).
文摘Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.
文摘With the rapid advancement of offshore wind power and the increasing scarcity of nearshore site resources,the development of offshore wind energy is inevitably moving towards deep seas.Floating offshore wind power technology is considered the primary technology for future offshore wind power development in deep seas.
基金Supported by the National Natural Science Foundation of China(51679080 and 51379073)the Fundamental Research Funds for the Central Universities(B230205020).
文摘This study employed a computational fluid dynamics model with an overset mesh technique to investigate the thrust and power of a floating offshore wind turbine(FOWT)under platform floating motion in the wind–rain field.The impact of rainfall on aerodynamic performance was initially examined using a stationary turbine model in both wind and wind–rain conditions.Subsequently,the study compared the FOWT’s performance under various single degree-of-freedom(DOF)motions,including surge,pitch,heave,and yaw.Finally,the combined effects of wind–rain fields and platform motions involving two DOFs on the FOWT’s aerodynamics were analyzed and compared.The results demonstrate that rain negatively impacts the aerodynamic performance of both the stationary turbines and FOWTs.Pitch-dominated motions,whether involving single or multiple DOFs,caused significant fluctuations in the FOWT aerodynamics.The combination of surge and pitch motions created the most challenging operational environment for the FOWT in all tested scenarios.These findings highlighted the need for stronger construction materials and greater ultimate bearing capacity for FOWTs,as well as the importance of optimizing designs to mitigate excessive pitch and surge.
基金funded by the Italian Ministry of Environment and Energy Security(MASE)-Direzione Generale per le Fonti energetiche e Titoli Abilitativi(DGFTA).
文摘The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir.The reuse plan involves removing outdated equipment from the platform’s decks while retaining essential components such as wellheads and separators.Exploiting a depleted reservoir for the injection of an H_(2)-CH_(4) mixture requires a thorough understanding of its specific characteristics.This paper focuses on the engineering approach adopted in the basic design phase for such a conversion,providing recommendations and HSE guidelines.Given the hazardous nature of substances like hydrogen in the gas mixture,the paper also examines potential risk scenarios,particularly those involving containment loss.A qualitative and quantitative assessment of these risks is conducted to evaluate their impact on the structure and equipment.The results of this assessment serve as a foundation for later studies on layout optimization and domino effect prevention.Additionally,some critical scenarios are simulated using an innovative approach known as the Source Box Accident Model(SBAM),which was proposed in previous works.SBAM leverages Computational Fluid Dynamics(CFD)but decouples the accidental phenomenon into a release phase and a dispersion phase.This method overcomes the challenges conventional CFD tools face in assessing congested plant configurations,providing more precise estimations of gas cloud behavior.The simulation results indicate that the released gas remains within the platform deck domain,and the flammable cloud is significantly smaller than what traditional,simplified tools predict.
基金This work is supported by the National Key Research and Development Program of China(No.2023YFB4203000)the National Natural Science Foundation of China(No.U22A20178)
文摘Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,we applied machine learning techniques to obtain hydrodynamic and aerodynamic loads of FOWTs by measuring platform motion responses and wave-elevation sequences.First,a computational fluid dynamics(CFD)simulation model of the floating platform was established based on the dynamic fluid body interaction technique and overset grid technology.Then,a long short-term memory(LSTM)neural network model was constructed and trained to learn the nonlinear relationship between the waves,platform-motion inputs,and hydrodynamic-load outputs.The optimal model was determined after analyzing the sensitivity of parameters such as sample characteristics,network layers,and neuron numbers.Subsequently,the effectiveness of the hydrodynamic load model was validated under different simulation conditions,and the aerodynamic load calculation was completed based on the D'Alembert principle.Finally,we built a hybrid-scale FOWT model,based on the software in the loop strategy,in which the wind turbine was replaced by an actuation system.Model tests were carried out in a wave basin and the results demonstrated that the root mean square errors of the hydrodynamic and aerodynamic load measurements were 4.20%and 10.68%,respectively.
基金Supported by the National Natural Science Foundation of China(No.41905089)the Laoshan Laboratory(No.LSKJ202202404)+1 种基金the Startup Foundation for Introducing Talent of NUIST,Jiangsu Innovation Research Group(No.JSSCTD202346)the Undergraduates Innovation and Entrepreneurship Training Program of Jiangsu Province(No.202310300087Y)。
文摘Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atmospheric Administration)CRW(Coral Reef Watch)daily mean sea surface temperature dataset spanning from 1985 to 2022 to comprehensively analyze the fundamental attributes and evolving patterns of marine heatwaves in the offshore waters of China.Eight pronounced marine heatwaves from frequently affected sensitive regions were investigated to explore their formation mechanisms.The relationship between the occurrences of marine heatwave and large-scale climate mode in the region was explored.Results show that the western Pacific subtropical high plays an essential role in triggering marine heatwaves in Chinese offshore waters,with an anomalous downward shortwave radiation flux acting to warm the sea surface,which is remotely associated to the large-scale sea surface temperature state.Distinct mechanisms for the MHWs were identified in the northern and southern offshore waters of China.MHWs in high latitudes(such as the Bohai Sea and the Yellow Sea)mainly occur during the negative phase of the Pacific Decadal Oscillation(PDO),while those in low latitudes(such as the South China Sea)are more common in about 5-month lags behind the El Niño,for which we purposed a mechanism to describe the main differences in the formation of MHWs in China and discussed the related implications.
