Effect of vessel hydrodynamic mass on the station-keeping response of a moored offshore vessel

An anchoring system for an offshore vessel must meet certain prescribed requirements controlled by factors such as the environment at site, the operational constraints and the vessel employed. Its adequacy, survival and ability to stay on site must therefore be checked out with proper methods of analysis. Since the inclusion of added mass is generally an important consideration in the dynamic analysis of a moored vessel, the effect of the hydrodynamic mass terms on the station-keeping response of an offshore construction vessel is investigated in this study from a viewpoint of mooring system design.     

Numerical study of a concept for major repair and replacement of offshore wind turbine blades

Repair and replacement of offshore wind turbine blades are necessary for current and future offshore wind turbines. To date, repair activities are often conducted using huge jack‐up crane vessels and by applying a reverse installation procedure. Because of the high costs associated with installation and removal of offshore wind turbine components and the low profit margin of the offshore wind industry, alternative methods for installation and removal are needed. This paper introduces a novel concept for replacement or installation of offshore wind turbine blades. The concept involves a medium‐sized jack‐up crane vessel and a tower climbing mechanism. This mechanism provides a stable platform for clamping, lowering, and lifting of a blade. A case study of a 5‐MW offshore wind turbine is shown, where common engineering practices were applied and numerical simulations of the marine operations were carried out using finite element and multibody simulation tools. Operational limits for wave and wind actions were established to demonstrate the technical feasibility of the proposed concept.     

一种新技术在海上风机基础冲刷防护的应用研究

  目的  随着我国海上风电开发的迅速发展,大直径单桩基础得到广泛应用,基础冲刷情况也日益严峻,选择合理适用的防冲刷方案对风电场长周期安全稳定运行、保证经济效益具有重要意义。  方法  通过某海上风电项目运行一年后大直径单管桩基础出现严重冲刷现象引出问题,对桩基础冲刷原理、目前国内外常规采取的防冲刷方案进行了概述,对某海上风电项目采用淤泥固化方案进行桩基础防冲刷试验的原理、参数、方案、工程实施进行了详述。  结果  通过对试验桩位长达两年的多次扫测、潜水员下水探摸,基本确定淤泥固化土层与桩身结合紧密、覆盖完整、试验效果良好。  结论  淤泥固化这种新型材料在海上风电基础的防冲刷应用具有一定的借鉴、推广意义。     

SPOWTT: Improving the safety and productivity of offshore wind technician transit

This paper describes the SPOWTT project. The intention of this project was to understand how sailing by crew transfer vessel (CTVs) to offshore wind farms affects the mental and physical wellbeing of individuals on board. The focus was on quantifying this impact, understanding the key drivers, with an aim to ensuring personnel can arrive to the wind turbines in a fit state to work safely and effectively. Impacts looked at subjective state beyond simply vomiting. Key results include the ability now to predict vessel motions from given Metocean conditions and vessel designs. We also discovered that the impact of vessel motions on seasickness is different for different symptoms and is driven not only by vertical z-axis accelerations but also by certain frequencies of motion in the y-axis. Frequencies other than 0.16 Hz were found to be impactful, and x-axis movements appeared to have a longer-lasting effect on the day's work. Through the formulation of a new, evidence-based understanding of seasickness, we have created an operational planning tool, designed to have a direct benefit on the safety and productivity of offshore wind farm operations.     

海上风电船机与风电设备故障分析及应对策略综述

[目的]海上风电船机及风电设备故障时常发生.为了减少风电故障发生的频率,需要对安装船机设备提出新的设计要求和具体故障的应对策略.[方法]通过对风电船机及设备的故障类型的对比研究分析,深入剖析各个故障类型发生的原因并提出相对应的应对策略.[结果]海上风电工程建设中,安装船机及风电设备主体是两大工程器械,也是施工过程中出现...     

An integrated systems framework for service vessel forecasting in the Gulf of Mexico

Throughout the world wherever oil and gas is discovered, a support industry will develop and evolve with the needs of industry and government regulation. In the Gulf of Mexico, a large variety of marine vessels transport goods and provide services to exploration, development and production activity, and play an important role in the economic and ecological impacts across communities. The spatial and temporal dynamics of the logistics network is complex and dynamic and closely related to the magnitude, duration, type, and sequence of offshore workflows and activities. The purpose of this paper is to develop a methodological framework to quantify the number of offshore supply vessel and crew boat departures by activity across the Gulf’s coastal regions in support of the oil and gas industry. The logistics network is modeled as a linear time-invariant deterministic system and implemented using an input-output model. We provide a methodological framework to quantify the magnitude and distribution of service vessel trips to forecast port activity. This is the first integrated modeling study on service vessel trips in the Gulf of Mexico and special attention is paid to the analytic framework, model assumptions, and limitations of the analysis. Generic examples illustrate the model implementation.     

新型40 m级测量船动力系统设计优化

针对40 m级测量船功能需求的提高,对新建40 m级测量船的动力系统进行优化,采用技术成熟的滑差齿轮箱驱动螺旋桨的推进方式取代可调螺距螺旋桨推进方式,使新建船在作业航区、测量作业能力等方面有较明显的提升,且船舶的灵活性和安全性得到进一步提高,满足了近海测量作业的实际需求。     

中右化胜利石油工程有限公司钻井工艺研究院

中石化胜利石油工程有限公司钻井工艺研宄院创建于1973年8月,主要从事石油钻完井、滩海石油工程新工艺、新技术、新材料、新装备的研究开发应用,钻井工程设计和技术服务。下设10个专业技术研究所、1个博士后工作分站、2个生产实验中心,配套形成了较完善的实验体系。先后取得ISO9001质量体系认证、API规范产品认证、HSE管理体系认证、海陆安全生产许可证、海洋工程及船舶设计资质,具有定向井水平井钻井工程技术、钻井液技术、钻井工程设计技术、取心技术、欠平衡和气体钻井技术5个中国石化集团公司甲级资质。每年承担省部级以上科研课题40项左右。     

广东海上风电岩土勘察船只平台技术研究

[目的]随着国家能源结构的加速演变,海上风电将进入快速稳定开发期.目前,国内多个省份近岸海上风电开发已接近完成,海上风电逐步向近海深水区开发并将大规模发展.近海深水区海上风电对海洋岩土勘察技术的要求更高,海洋岩土勘察船只和设备要求趋于专业化.国内大型专业海洋岩土勘察平台数量有限,其主要服务于国家海洋资源勘探和科考工作,...     

Environmental and social footprint of offshore wind energy. Comparison with onshore counterpart

Offshore wind power comprises a relatively new challenge for the international wind industry with a demonstration history of around twenty years and a ten-year commercial history for large, utility-scale projects. By comparison to other forms of electric power generation, offshore wind energy is generally considered to have relatively benign effects on the marine environment. However, offshore projects include platforms, turbines, cables, substations, grids, interconnection and shipping, dredging and associated construction activity. The Operation & Maintenance (O&M) activities include the transport of employees by vessel or helicopter and occasional hardware retrofits. Therefore, various impacts are incurred in the construction, operation and decommissioning phases; mainly the underwater noise and the impacts on the fauna. Based on the fact that in many of the aforementioned issues there are still serious environmental uncertainties, contradictive views and emerging research, the present work intents to provide a thorough literature review on the environmental and social impacts of offshore wind energy projects in comparison with the onshore counterparts.     

Likelihood of a marine vessel accident from wind energy development in the Atlantic

Offshore wind energy development is planned for areas off the Atlantic coast. Many of the planned wind development areas fall within traditional commercial vessel routes. In order to mitigate possible hazards to ships and to wind turbines, it is important to understand the potential for increased risk to commercial shipping from the presence of wind farms. Risk is identified as the likelihood that an occurrence will happen, and the consequences of that occurrence, should it occur. This paper deals with the likelihood of commercial vessel accidents, because of the development of offshore wind energy along the US Atlantic coast. Using Automatic Identification System (AIS) data, historical shipping routes between ports in the Atlantic were identified, from Maine to the Florida Straits. The AIS data were also used as inputs to a numerical model that can simulate cargo, tanker and tug/towing vessel movement along typical routes. The model was used to recreate present day vessel movement, as well as to simulate future routing that may be required to avoid wind farms. By comparing the present and future routing of vessels, an analysis of potential maritime accidents was used to determine the increased marginal risk of vessel collisions, groundings and allisions with stationary objects, because of the presence of wind farms. The outcome of the analysis showed little increase in vessel collisions or allisions, and a decrease in groundings as more vessels were forced seaward by the wind farms. Copyright © 2015 John Wiley & Sons, Ltd.     

双体风电运维船阻力CFD计算及降阻设计研究

[目的]船舶阻力直接影响着船舶的快速性能,对于一艘海上风电运维船,快速性能是此船舶的重要性能指标之一.因此,需要计算船舶的阻力并研究有效的阻力优化方法.[方法]基于CFD方法,建立了数值模型,对某19.1 m长的双体海上风电运维船的阻力性能进行了研究,计算并分析10 kn、13 kn、16 kn和20 kn这四个不同航...     

A Bayesian hierarchical assessment of night shift working for offshore wind farms

This article presents a Bayesian data-modelling approach to assessing operational efficiency at offshore wind farms. Input data are provided by an operational database provided by a large offshore wind farm which employs an advanced data management system. We explore the combination of datasets making up the database, using them to train a Bayesian hierarchical model which predicts weekly lost production from corrective maintenance and time-based availability. The approach is used to investigate the effect of technician work shift patterns, specifically addressing a strategy involving night shifts for corrective maintenance which was employed at the site throughout the winter. It was found that, for this particular site, there is an approximate annual increase in time-based technical availability of 0.64%. We explore the effect of modelling assumptions on cost savings; specifically, we explore variations in failure rate, price of electricity, number of technicians working night shift, extra staff wages, months of the year employing 24/7 working and extra vessel provision. Results vary quite significantly among the scenarios investigated, exemplifying the need to consider the question on a farm-by-farm basis.     

海上风电场智能船舶调度及人员管理系统

  [目的]  对海上风电场的人员、船舶进行管理、指挥、调度,是海上风电领域的新课题。建立了国内首个海上风电场智能船舶调度及人员管理系统。  [方法]  主要包括（1）高效指挥调度方式:基于海事高频VHF的船用对讲系统,用以实现稳定的对讲通信;利用AIS接收机和海事电台,可获取周围船只的信息和地理位置,并同时对进入警戒区域的船只进行记录的存档和对讲驱赶;人员落水后陆上项目部指挥中心会得到报警信号并获取落水人员的位置;（2）海域实时监测系统:通过一台远红外热成像摄像机,用于远程监控海上风电场的情况;同时,通过测风塔上的两台摄像机、气象传感器,用来监控海上风电场附近的海域状况和浪涌情况;（3）精准气象预测系统:海洋气象预报可对现场环境的风速、风浪、浪涌等进行一周的预报,并可对台风进行跟踪预报。  [结果]  结果表明:方案可靠,能有效对海上风电场人员和船只进行管理,降低建设运维成本。  [结论]  智能船舶调度及人员管理系统,对海上风电场的生产安全管理和运维效率的提升,起到重要的作用。     

大规模海上风电集中送出建设模式研究

[目的]当前海上风电已成为全球风电发展的研究热点。我国海上风电尚处于起步阶段,而当前的运营模式存在不利于海上风电大规模集中送出等缺点,无法适应新形势下的长远发展。另一方面,欧洲各国对海上风电的补贴政策与我国当前的发展思路有所冲突,可借鉴性不强,且欧洲模式本身仍存在弊端。因此亟需探索适合我国近海深水区海上风电发展的新模式。[方法]首先分析了欧洲各国海上风电发展现状,并对海上风电输电模式进行总结;其次给出了四种海上风电输电技术应用场景;最后对海上风电商业模式进行了可行性分析。[结果]结果表明：在拆分海上发、输电侧环节后,广东省预计“十四五”期间能够实现平价上网;相比于分散式开发,深水区海上风电统筹集约式开发从经济性及环境集约利用层面更具有优势。[结论]形成的研究结论可以为后续大规模海上风电集中送出项目的方案设计和建设模式提供技术支持,具有很好的示范应用前景。     

Visual impact assessment of offshore wind farms and prior experience

Energy planners have shifted their attention towards offshore wind power generation and the decision is supported by the public in general, which in the literature has a positive attitude towards offshore wind generation. However, globally only a few offshore wind farms are operating. As more wind farms start operating and more people become experienced with especially the visual impacts from offshore wind farms, the public positive attitude could change if the experienced impacts are different from the initially perceived visual interference. Using a binary logit model, the present paper investigates the relation between different levels of prior experience with visual disamenities from offshore wind farms and perception of visual impacts from offshore wind farms. The differences in prior experience are systematically controlled for sampling respondents living in the areas close to the large scale offshore wind farms Nysted and Horns Rev and by sampling the a group of respondents representing the Danish population, which has little experience with offshore wind farms. Compared to previous results in the literature, the present paper finds that perception of wind power generation is influenced by prior experience. More specifically, the results show that people with experience from offshore wind farms located far from the coast have a significant more positive perception of the visual impacts from offshore wind farms than people with experience from wind farms located closer to the coast. These results are noteworthy on two levels. First of all, the results show that perceptions of offshore wind generation are systematically significantly influenced by prior experience with offshore wind farms. Secondly, and in a policy context, the results indicate that the future acceptance of future offshore wind farms is not independent of the location of existing and new offshore wind farms. This poses for caution in relation to locating offshore wind farms too close to the coast.     

Ecological and economic cost-benefit analysis of offshore wind energy

Wind energy has experienced dramatic growth over the past decade. A small fraction of this growth has occurred offshore, but as the best wind resources become developed onshore, there is increasing interest in the development of offshore winds. Like any form of power production, offshore wind energy has both positive and negative impacts. The potential negative impacts have stimulated a great deal of opposition to the first offshore wind power proposals in the U.S. and have delayed the development of the first offshore wind farm in the U.S. Here we discuss the costs and benefits of offshore wind relative to onshore wind power and conventional electricity production. We review cost estimates for offshore wind power and compare these to estimates for onshore wind and conventional power. We develop empirical cost functions for offshore wind based on publicly reported projects from 2000 to 2008, and describe the limitations of the analysis. We use this analysis to inform a discussion of the tradeoffs between conventional, onshore and offshore wind energy usage.     

LNG-FPSO: Offshore LNG solution

The floating production, storage and offloading system for liquefied natural gas (LNG-FPSO), is a new conceptual unit and an effective and realistic way for exploitation, recovery, storage, transportation and end-use applications of marginal gas fields and offshore associated-gas resources. However, a real LNG-FPSO unit cannot be built unless some breakthroughs in many key technologies are produced. Many unique characteristics of LNG-FPSO, such as restricted space, platform motion, LNG sloshing in inner storage tank and offloading system, which have not been considered in the onshore projects, are the most rigorous factors to be taken into account during design. In this paper, the overall layout of a typical LNG-FPSO unit is reviewed; the leading liquefaction technologies and processes are compared and discussed. Taking the effects of the vessel motion and limited space into account, the applicability of the main systems and key equipments of storage, offloading and power supply, are analyzed.     

Offshore wind energy in the world context

The interest for the exploitation of the offshore wind energy is growing in Europe, where man land use is very high resulting in strong limitation to the installation of onshore wind farms. The today offshore operating wind power is 12 MW, with two wind farms in Denmark and one in Netherlands; it starts to be significant (0.6%) in terms of the onshore power, 2000 MW in Europe.In the world the onshore installed wind power is exceeding 4000 MW, but not so much up to now has been done on the offshore area outside Europe.The European four years experience on the prototypical offshore wind farms looks significantly promising and suggests to promote a similar approach in many densely populated coastal countries in the world with high electricity demand.Results of studies are presented on the offshore wind potential in the European countries and of the tentative evaluation for the Mediterranean basin, and the seas of USA and China. A review is made of the offshore applications, particularly for the Nothern European seas.Economy and environmental trends are illustrated in parallel to those of maturing offshore technology. It is suggested to prepare an action plan to promote the development of the offshore applications in the world context.     

Coordinate control strategy for stability operation of offshore wind farm integrated with Diode-rectifier HVDC

Due to low investment cost and high reliability, a new scheme called DR-HVDC (Diode Rectifier based HVDC) transmission was recently proposed for grid integration of large offshore wind farms. However, in this scheme, the application of conventional control strategies for stability operation face several challenges due to the uncontrollability of the DR. In this paper, a coordinated control strategy of offshore wind farms using the DR-HVDC transmission technology to connect with the onshore grid, is investigated. A novel coordinated control strategy for DR-HVDC is proposed based on the analysis of the DC current control ability of the full-bridge-based modular multilevel converter (FB-MMC) at the onshore station and the input and output characteristics of the diode rectifier at the offshore. Considering the characteristics of operation stability and decoupling between reactive power and active power, a simplified design based on double-loop droop control for offshore AC voltage is proposed after power flow and voltage–current (I–V) characteristics of the offshore wind farm being analyzed. Furthermore, the impact of onshore AC fault to offshore wind farm is analyzed, and a fast fault detection and protection strategy without relying on communication is proposed. Case studies carried out by PSCAD/EMTDC verify the effectiveness of the proposed control strategy for the start up, power fluctuation, and onshore and offshore fault conditions.