Mooring Sense Project: A Risk-Based Integrity Management Strategy for Mooring System of Floating Offshore Wind

2021 ◽  
Author(s):  
Alessandro La Grotta ◽  
Róisín Louise Harris ◽  
Clive Da Costa
Keyword(s):  
Energy Production ◽  
Management Strategy ◽  
Offshore Wind ◽  
Risk Level ◽  
Mooring System ◽  
Inspection Planning ◽  
Potential Cost ◽  
Operational Costs ◽  
Floating Offshore Wind Turbines ◽  
Integrity Management

Abstract While Floating Offshore Wind (FOW) represents a significant opportunity to foster wind energy development and to contribute to remarkable CO2 emissions reductions, its associated operational costs are still substantially above grid parity, and significant innovation is needed. MooringSense is a research and innovation project which explores digitisation technologies to enable the implementation of risk-based integrity management strategies for mooring systems in the FOW sector with the aim to optimise Operations and Maintenance (O&M) activities, reduce costs, and increase energy production. As part of this project, a risk-based assessment methodology specific for the mooring system of Floating Offshore Wind Turbines (FOWT) has been developed; this allows the development of a risk-based Mooring Integrity Management Strategy that can result in more cost-effective inspection planning. The methodology shall utilise the information made available by numerical tools, sensors, and algorithms developed in the project to update the risk level of the mooring system and set the required plan to mitigate the risk. Leveraging the additional information from monitoring technologies and predictive capabilities to determine the mooring system condition and remaining lifetime, the strategy provides the criteria for optimal decision making with regards to selection of O&M activities. The risk-based strategy developed allows for optimal planning of inspection and maintenance activities based on dynamic risk level that is periodically updated through the interface with the Digital Twin (DT). The validation of the strategy will demonstrate potential cost saving and economic advantages, however, it is expected that the overall MooringSense approach can reduce FOW farm operational costs by 10-15% and increase operational efficiency by means of an Annual Energy Production increase by 2-3%. The MooringSense project comprises of the development and validation of innovative solutions coming from multiple disciplines such as numerical modelling, simulation, Global Navigation Satellite System (GNSS), Structural Health Monitoring (SHM), and control systems which will provide valuable input to the risk-based mooring integrity management strategy.

scholarly journals Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

2021 ◽  
Vol 11 (24) ◽  
pp. 11665
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chao Wang ◽  
Yuangang Tu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Included Angle ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

A Concept for Floating Offshore Wind Mooring System Integrity Management Based on Monitoring, Digital Twin and Control Technologies

2021 ◽  
Author(s):  
Alberto Puras Trueba ◽  
Jonathan Fernández ◽  
Carlos A. Garrido-Mendoza ◽  
Alessandro La Grotta ◽  
Jon Basurko ◽  
...  
Keyword(s):  
Control Strategies ◽  
Offshore Wind ◽  
Motion Sensor ◽  
Mooring System ◽  
Mooring Lines ◽  
Efficient Operation ◽  
Digital Twin ◽  
System Integrity ◽  
Integrity Management ◽  
And Control

Abstract Efficient operation of mooring systems is of paramount importance to reduce floating offshore wind (FOW) energy costs. MooringSense is an R&D project which explores digitization to enable the implementation of more efficient integrity management strategies (IMS) for FOW mooring systems. In this work, the MooringSense concept is presented. It includes the development of several enablers such as a mooring system digital twin, a smart motion sensor, a structural health monitoring (SHM) system and control strategies at the individual turbine and farm levels. The core of the digital twin (DT) is a high-fidelity fully coupled numerical model which integrates simulation tools to allow predictive operation and maintenance (O&M). Relevant parameters of the coupled model are updated as physical properties evolve due to damages or degradation. The DT assimilates information coming from the physical asset and environmental sensors. Besides, a smart motion sensor provides feedback of the attitude, position, and velocity of the floater to allow the computation of virtual loads in the mooring lines, the detection of damages by the SHM system and the implementation of closed-loop control strategies. Finally, the IMS takes advantage of the mooring system updated condition information to optimize O&M, reduce costs and increase energy production.

Dynamic Responses of a Spar Type Floating Offshore Wind Turbine With Failed Moorings

2020 ◽  
Author(s):  
Yajun Ren ◽  
Vengatesan Venugopal
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Platform Motions

Abstract The complex dynamic characteristics of Floating Offshore Wind Turbines (FOWTs) have raised wider consideration, as they are likely to experience harsher environments and higher instabilities than the bottom fixed offshore wind turbines. Safer design of a mooring system is critical for floating offshore wind turbine structures for station keeping. Failure of mooring lines may lead to further destruction, such as significant changes to the platform’s location and possible collisions with a neighbouring platform and eventually complete loss of the turbine structure may occur. The present study focuses on the dynamic responses of the National Renewable Energy Laboratory (NREL)’s OC3-Hywind spar type floating platform with a NREL offshore 5-MW baseline wind turbine under failed mooring conditions using the fully coupled numerical simulation tool FAST. The platform motions in surge, heave and pitch under multiple scenarios are calculated in time-domain. The results describing the FOWT motions in the form of response amplitude operators (RAOs) and spectral densities are presented and discussed in detail. The results indicate that the loss of the mooring system firstly leads to longdistance drift and changes in platform motions. The natural frequencies and the energy contents of the platform motion, the RAOs of the floating structures are affected by the mooring failure to different degrees.

Demonstration of the Intelligent Mooring System for Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Magnus J. Harrold ◽  
Philipp R. Thies ◽  
Peter Halswell ◽  
Lars Johanning ◽  
David Newsam ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Wind ◽  
Mooring System ◽  
Gas Industry ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Physical Testing ◽  
Line Loads

Abstract Existing mooring systems for floating offshore wind turbines are largely based on designs from the oil and gas industry. Even though these can ensure the safe station keeping of the floating wind platform, the design of the mooring system is currently largely conservative, leading to additional expense in an industry striving to achieve cost reduction. Recent interest in the usage of mooring materials with non-linear stiffness has shown that they have the potential to reduce peak line loads, ultimately reducing cost. This paper reports on the combined physical testing and numerical modeling of a hydraulic-based mooring component with these characteristics. The results suggest that the inclusion of the component as part of the OC4 semi-submersible platform can reduce the peak line loads by 10%. The paper also discusses a number of challenges associated with modeling and testing dynamic mooring materials.

Integrity Management Challenges for Commercial-Scale Floating Wind Farms

2018 ◽  
Author(s):  
Christopher Carra ◽  
Andrew Kilner ◽  
Andrew Potts ◽  
David Rowley ◽  
Victoria Ryan
Keyword(s):  
Dynamic Behavior ◽  
Wind Farm ◽  
Deep Understanding ◽  
Offshore Wind ◽  
Operating Costs ◽  
Local Dynamic ◽  
Mooring System ◽  
Commercial Scale ◽  
Integrity Management ◽  
Offshore Oil

Large-scale deployment of multiple structures within a Floating Offshore Wind Farm (FOWF) will place many challenges on both the approach to effective integrity management and the demand to reduce through-life operating costs. Additionally, wind farm designers and operators will need to consider the issues related to design robustness in the design of their systems, whereby rational robustness criteria are applied to address possible accidental conditions that are not explicitly addressed in code-specified design basis conditions. This paper will review the significant advances in the approach to integrity management that have been recently made in the mature offshore oil industry and relate them to the nascent offshore wind industry. In particular, the requirement for consideration across the full lifecycle of the potential for threat introduction and the application of controls to prevent or mitigate the evolution of those threats will be described. This includes threats that may be inadvertently introduced during the design, manufacturing and installation phases, in addition to the more traditional rate-based degradation mechanisms such as fatigue, corrosion and wear that occur once the facility is in operation. The challenges that commercial-scale wind farm developments will face relate particularly to integrity issues arising in the design, manufacturing and installation phases, where the focus needs to ensure that degradation threats are not being introduced into the deployment of multiple repeat-copy units. The issues of common cause/common mode degradation threats will have much higher significance for a commercial-scale wind farm, where rectification of a common issue across a large number of floating units could have significant impacts in terms of reliability, operating costs, insurance premiums and power purchase agreements. FOWF mooring system designs are also likely to be more optimized than that for a typical one-off offshore oil facility. This will require the wind farm designer to have a deep understanding of the fundamental dynamic behavior of the overall system and the local dynamic behaviors of the components within the mooring system in order to be able to fully identify the types of threats that may be present. This may also involve robustness considerations where there may be step changes in the dynamic behavior of the system, often termed as cliff-edge effects. The paper will outline issues that wind farm designers will need to consider in building integrity considerations into the design and execution phases of a development, as well as the opportunities that risk-based integrity management processes offer in terms of through-life condition verification and inspection optimization.

scholarly journals Fault Detection of the Mooring system in Floating Offshore Wind Turbines based on the Wave-excited Linear Model

2020 ◽  
Vol 1618 ◽  
pp. 022049
Author(s):  
Yichao Liu ◽  
Alessandro Fontanella ◽  
Ping Wu ◽  
Riccardo M.G. Ferrari ◽  
Jan-Willem van Wingerden
Keyword(s):  
Fault Detection ◽  
Linear Model ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Mooring System ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Snap Load Criteria for Mooring Lines of a Floating Offshore Wind Turbine

2018 ◽  
Author(s):  
Wei-Ting Hsu ◽  
Krish P. Thiagarajan ◽  
Lance Manuel
Keyword(s):  
Numerical Simulations ◽  
Shallow Water ◽  
Line Tension ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Floating Offshore Wind Turbines ◽  
Storm Condition ◽  
Impact Events

There are several challenges facing the design of mooring system of floating offshore wind turbines (FOWTs), including installation costs, stability of lightweight minimalistic platforms, and shallow water depths (50–300m). For station keeping of FOWTs, a proper mooring system is required in order to maintain the translational motions in surge and sway and the rotational motions in yaw of the platform within an adequate range. A combination of light pre-tension, shallow water depth and large platform motions in response to a survival storm condition can result in snap-type impact events on mooring lines, thus increasing the line tension dramatically. In this paper, we present a new snap load criterion applicable to a catenary mooring system and compare it with Det Norske Veritas’ criterion for marine operations. As a case study, we examine the extreme tension on a catenary mooring system of a semi-submersible FOWT exposed to a 100-year storm condition. The software OrcaFlex was used for numerical simulations of the mooring system. NREL’s FAST software was coupled to OrcaFlex to obtain aerodynamic loads along with hydrodynamic loads for FOWT analyses. Snap-type impact events were observed in the numerical simulations and were characterized by two criteria. Tension maxima were fitted using composite Weibull distributions (CWDs) and comparisons of probability exceedance were made for the two different snap load criteria.

scholarly journals Investigation of Hydrodynamic Forces for Floating Offshore Wind Turbines on Spar Buoys and Tension Leg Platforms with the Mooring Systems in Waves

2019 ◽  
Vol 9 (3) ◽  
pp. 608 ◽  
Author(s):  
Yu-Hsien Lin ◽  
Shin-Hung Kao ◽  
Cheng-Hao Yang
Keyword(s):  
Wind Turbines ◽  
Time Domain ◽  
Simulation System ◽  
Offshore Wind ◽  
Modular System ◽  
Mooring System ◽  
Mooring Lines ◽  
Offshore Wind Turbines ◽  
Motion Responses ◽  
Floating Offshore Wind Turbines

This study aims to develop a modularized simulation system to estimate dynamic responses of floating Offshore Wind Turbines (OWTs) based on the concepts of spar buoy and Tension Leg Platform (TLP) corresponding with two typical mooring lines. The modular system consists of the hydrodynamic simulator based the Cummins time domain equation, the Boundary Element Method (BEM) solver based on the 3D source distribution method, and an open-source visualization software ParaView to analyze the interaction between floating OWTs and waves. In order to realize the effects of mooring loads on the floating OWTs, the stiffness and damping matrices are applied to the quasi-static mooring system. The Response Amplitude Operators (RAOs) are compared between our predicted results and other published data to verify the modularized simulation system and understand the influence of mooring load on the motion responses in regular or irregular waves. It is also demonstrated that the quasi-static mooring system is applicable to different types of mooring lines as well as determining real-time motion responses. Eventually, wave load components at the resonance frequencies of different motion modes for selected floating OWTs would be present in the time domain.

An Overview of Risk-Based Inspection Planning for Flexible Pipeline

2018 ◽  
Author(s):  
Hamad Hameed ◽  
Guowei Sun ◽  
Yong Bai
Keyword(s):  
Failure Mechanisms ◽  
Cost Effective ◽  
Initial Assessment ◽  
Risk Level ◽  
Pipeline System ◽  
Inspection Planning ◽  
Flexible Pipes ◽  
System Risk ◽  
Integrity Management ◽  
Detailed Assessment

There are many failure mechanisms that may occur in flexible pipes during their service life, such as external sheath damage, damage of tensile armours due to fatigue, kinks due to corrosion, and over-bending. The above mentioned defects are very common and can lead to the failure of flexible pipes. Therefore, huge operational costs have to be spent to ensure the integrity of the flexible pipeline system. Risk-Based inspection (RBI) methodology can establish a cost-effective strategy for inspection and monitoring, while maintaining the expected level of safety. However, there are some factors that can hamper the development of an optimized RBI for the integrity management of flexible pipelines, such as the complexity and variety of flexible pipes’ multi-layer structures with their interacting failure mechanisms, the somewhat poor defect capability of the existing inspection techniques and the lack of broad [1]. In this paper, RBI planning is described thoroughly to ensure the integrity management of flexible pipelines. All risk terms have been described in detail with respect to integrity management strategy. The working process of RBI, including initial assessment and detailed assessment, is introduced. Estimation and evaluation of risk level, including the development of optimized inspection planning, have been described completely.

scholarly journals Large-scale testing of a hydraulic non-linear mooring system for floating offshore wind turbines

2020 ◽  
Vol 206 ◽  
pp. 107386
Author(s):  
Magnus J. Harrold ◽  
Philipp R. Thies ◽  
David Newsam ◽  
Claudio Bittencourt Ferreira ◽  
Lars Johanning
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Offshore Wind ◽  
Mooring System ◽  
Offshore Wind Turbines ◽  
Large Scale Testing ◽  
Floating Offshore Wind Turbines ◽  
Non Linear
Sign in / Sign up

Export Citation Format

Share Document