The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform

David Mcmillan - One of the best experts on this subject based on the ideXlab platform.

  • operational strategies for offshore wind turbines to mitigate failure rate uncertainty on operational costs and revenue
    Iet Renewable Power Generation, 2014
    Co-Authors: Iain Dinwoodie, David Mcmillan
    Abstract:

    Several operational strategies for offshore wind farms have been established and explored in order to improve understanding of operational costs with a focus on Heavy Lift Vessel strategies. Additionally, an investigation into the uncertainty surrounding failure behaviour has been performed identifying the robustness of different strategies. Four operational strategies were considered: fix on fail, batch repair, annual charter and purchase. A range of failure rates have been explored identifying the key cost drivers and under which circumstances an operator would choose to adopt them. When failures are low, the fix on fail and batch strategies perform best and allow flexibility of operating strategy. When failures are high, purchase becomes optimal and is least sensitive to increasing failure rate. Late life failure distributions based on mechanical and electrical components behaviour have been explored. Increased operating costs because of wear-out failures have been quantified. An increase in minor failures principally increase lost revenue costs and can be mitigated by deploying increased maintenance resources. An increase in larger failures primarily increases Vessel and repair costs. Adopting a purchase strategy can negate the Vessel cost increase; however, significant cost increases are still observed. Maintenance actions requiring the use of Heavy Lift Vessels, currently drive train components and blades are identified as critical for proactive maintenance to minimise overall maintenance costs.

  • Forecasting long term jack up Vessel demand for offshore wind
    2013
    Co-Authors: David Mcmillan, Iain Dinwoodie
    Abstract:

    Offshore wind deployment has greatly increased in the last decade. The number and size of installations have historically determined the requirement for jack up Vessels, as installation was the only driver for Heavy Lift Vessel requirement. The next phase of offshore wind development will change this situation, as jack up requirement for operations and maintenance will certainly increase as assets age, and in parallel larger sites con-tinue to be installed and commissioned. The approach taken in this paper is to develop a long-term Vessel demand model. This is achieved by a two stage process: firstly an installation jack up demand model is developed using UK offshore wind data for projects installed in the period 2003-2016. This model is utilized in tandem with an operations and maintenance jack up requirement model which is based on published reliability figures and failure duration data. The combined model captures the requirement for jack up Vessels in the period 2012-2030. The paper concludes that demand for jack up Vessels in UK waters will ramp up significantly in this decade, with an initial peak in 2014. A secondary peak around 2028 is highly dependent on assumptions regarding the trajectory of the turbine failure rate over time.

  • Heavy Lift Vessel strategy analysis for offshore wind
    2013
    Co-Authors: Iain Dinwoodie, David Mcmillan
    Abstract:

    To minimise the future cost of energy for future large, remote offshore wind farms, new maintenance methodologies may be required. This paper presents a modelling framework to test these maintenance methodologies in order to determine where different operational choices represent the cost optimal solution. The sensitivity of operational strategies to wind farm size as well as failure rates of major components has been examined in order to demonstrate the capability of the modelling approach as well as identify the strengths and weaknesses of the strategies. Fix on fail methodology has been identified as cost effective only for small wind farms where failure rates are low. Vessel purchase becomes cost effective when the wind farm is sufficiently large or failure rate is high. A batch repair approach is shown to provide comparable costs to purchasing a Vessel without the large capital costs but reduces the overall power produced. Several additional areas for future model development and research have been identified.

René Huijsmans - One of the best experts on this subject based on the ideXlab platform.

  • ‘WET HANDSHAKE’, WORKABILITY STUDY OF AN OFFSHORE THRUSTER EXCHANGE OPERATION
    2015
    Co-Authors: Henk Feikens, Roel Verwey, Jorrit-jan Serraris, Wageningen The Netherlands, René Huijsmans
    Abstract:

    Thruster exchange operations are performed when an azimuth thruster on a DP operated Vessel needs to be replaced for repair or maintenance purposes. At present these operations are performed either during a dry-dock call or in sheltered waters with the assistance of a shearleg or Heavy Lift Vessel moored alongside the DP operated Vessel. In order to reduce downtime of the DP operated Vessel a clear trend is observed of operations being carried out more offshore and in deeper waters by means of a wet handshake between a Heavy Lift Vessel (HLV) and a DP operated Vessel. To get insight into the workability of such offshore thruster exchange operations it is important to study the dynamic interactions between the bodies involved. This paper describes the development of a methodology which accurately determines the workability of an offshor

  • ‘Wet Handshake’: Workability Study of an Offshore Thruster Exchange Operation
    Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology, 2011
    Co-Authors: Henk Feikens, Roel Verwey, Jorrit-jan Serraris, René Huijsmans
    Abstract:

    Thruster exchange operations are performed when an azimuth thruster on a DP operated Vessel needs to be replaced for repair or maintenance purposes. At present these operations are performed either during a dry-dock call or in sheltered waters with the assistance of a shearleg or Heavy Lift Vessel moored alongside the DP operated Vessel. In order to reduce downtime of the DP operated Vessel a clear trend is observed of operations being carried out more offshore and in deeper waters by means of a wet handshake between a Heavy Lift Vessel (HLV) and a DP operated Vessel. To get insight into the workability of such offshore thruster exchange operations it is important to study the dynamic interactions between the bodies involved. This paper describes the development of a methodology which accurately determines the workability of an offshore thruster exchange operation. The methodology is developed by BigLift Shipping, which has performed several thruster exchange operations in sheltered waters in the past few years. Furthermore the results of a workability analysis of a thruster exchange operation offshore Ghana are presented. In order to determine workability, first the hydrodynamic behavior including interaction effects of the coupled configuration of the DP operated Vessel, the Heavy Lift Vessel and the azimuthing thruster is calculated for a range of seastates, which results in the response spectra of the Vessels. Then for each seastate the response is compared with the defined operational criteria to determine whether this seastate is workable, critical or non-workable, which results in a workability diagram. The workability can be quantified by combining this workability diagram with a wave-scatter diagram of the location of interest. In general this is a thoroughly studied topic. In order to achieve a higher level of accuracy of the workability prediction the focus of the methodology described in this paper has been pointed on two aspects that can be of significant influence. • First the persistency of a certain seastate is investigated. In the approach described above any variation of the environmental conditions over the duration of the operation is not considered. The effect of changing weather in time can be of significant influence on the overall workability. In order to take into account persistency information a numerical dataset of 3 hours statistics over a period of 10 years is used. Combining this information with the duration of all consecutive steps of the operation, results in a more realistic workability prediction. Similar approaches in seakeeping of ships are shown by Dallinga et al. (2004) [1], Naito et al. (2006) [2]. • Secondly the influence of a frequency domain approach compared to a time domain approach is analyzed. The nonlinear effects that occur in the coupled configuration of multiple bodies can not be taken into account in the frequency domain approach. Therefore the motion analysis is performed in the time domain. As an example case a thruster exchange operation offshore Ghana has been studied. The results of the study show that the workability prediction based on scatter diagram metocean data is influenced substantially when persistency information of metocean data is taken into account. The effect of the duration and criteria of independent operational steps on the workability are clearly visible in the persistency approach. This enables a to-the-point approach in improving the workability. Although time domain analysis is taking into account nonlinear effects, the difference between time and frequency domain analysis can be neglected for the presently studied configuration.Copyright © 2011 by ASME

Iain Dinwoodie - One of the best experts on this subject based on the ideXlab platform.

  • operational strategies for offshore wind turbines to mitigate failure rate uncertainty on operational costs and revenue
    Iet Renewable Power Generation, 2014
    Co-Authors: Iain Dinwoodie, David Mcmillan
    Abstract:

    Several operational strategies for offshore wind farms have been established and explored in order to improve understanding of operational costs with a focus on Heavy Lift Vessel strategies. Additionally, an investigation into the uncertainty surrounding failure behaviour has been performed identifying the robustness of different strategies. Four operational strategies were considered: fix on fail, batch repair, annual charter and purchase. A range of failure rates have been explored identifying the key cost drivers and under which circumstances an operator would choose to adopt them. When failures are low, the fix on fail and batch strategies perform best and allow flexibility of operating strategy. When failures are high, purchase becomes optimal and is least sensitive to increasing failure rate. Late life failure distributions based on mechanical and electrical components behaviour have been explored. Increased operating costs because of wear-out failures have been quantified. An increase in minor failures principally increase lost revenue costs and can be mitigated by deploying increased maintenance resources. An increase in larger failures primarily increases Vessel and repair costs. Adopting a purchase strategy can negate the Vessel cost increase; however, significant cost increases are still observed. Maintenance actions requiring the use of Heavy Lift Vessels, currently drive train components and blades are identified as critical for proactive maintenance to minimise overall maintenance costs.

  • Forecasting long term jack up Vessel demand for offshore wind
    2013
    Co-Authors: David Mcmillan, Iain Dinwoodie
    Abstract:

    Offshore wind deployment has greatly increased in the last decade. The number and size of installations have historically determined the requirement for jack up Vessels, as installation was the only driver for Heavy Lift Vessel requirement. The next phase of offshore wind development will change this situation, as jack up requirement for operations and maintenance will certainly increase as assets age, and in parallel larger sites con-tinue to be installed and commissioned. The approach taken in this paper is to develop a long-term Vessel demand model. This is achieved by a two stage process: firstly an installation jack up demand model is developed using UK offshore wind data for projects installed in the period 2003-2016. This model is utilized in tandem with an operations and maintenance jack up requirement model which is based on published reliability figures and failure duration data. The combined model captures the requirement for jack up Vessels in the period 2012-2030. The paper concludes that demand for jack up Vessels in UK waters will ramp up significantly in this decade, with an initial peak in 2014. A secondary peak around 2028 is highly dependent on assumptions regarding the trajectory of the turbine failure rate over time.

  • Heavy Lift Vessel strategy analysis for offshore wind
    2013
    Co-Authors: Iain Dinwoodie, David Mcmillan
    Abstract:

    To minimise the future cost of energy for future large, remote offshore wind farms, new maintenance methodologies may be required. This paper presents a modelling framework to test these maintenance methodologies in order to determine where different operational choices represent the cost optimal solution. The sensitivity of operational strategies to wind farm size as well as failure rates of major components has been examined in order to demonstrate the capability of the modelling approach as well as identify the strengths and weaknesses of the strategies. Fix on fail methodology has been identified as cost effective only for small wind farms where failure rates are low. Vessel purchase becomes cost effective when the wind farm is sufficiently large or failure rate is high. A batch repair approach is shown to provide comparable costs to purchasing a Vessel without the large capital costs but reduces the overall power produced. Several additional areas for future model development and research have been identified.

Henk Feikens - One of the best experts on this subject based on the ideXlab platform.

  • ‘WET HANDSHAKE’, WORKABILITY STUDY OF AN OFFSHORE THRUSTER EXCHANGE OPERATION
    2015
    Co-Authors: Henk Feikens, Roel Verwey, Jorrit-jan Serraris, Wageningen The Netherlands, René Huijsmans
    Abstract:

    Thruster exchange operations are performed when an azimuth thruster on a DP operated Vessel needs to be replaced for repair or maintenance purposes. At present these operations are performed either during a dry-dock call or in sheltered waters with the assistance of a shearleg or Heavy Lift Vessel moored alongside the DP operated Vessel. In order to reduce downtime of the DP operated Vessel a clear trend is observed of operations being carried out more offshore and in deeper waters by means of a wet handshake between a Heavy Lift Vessel (HLV) and a DP operated Vessel. To get insight into the workability of such offshore thruster exchange operations it is important to study the dynamic interactions between the bodies involved. This paper describes the development of a methodology which accurately determines the workability of an offshor

  • ‘Wet Handshake’: Workability Study of an Offshore Thruster Exchange Operation
    Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology, 2011
    Co-Authors: Henk Feikens, Roel Verwey, Jorrit-jan Serraris, René Huijsmans
    Abstract:

    Thruster exchange operations are performed when an azimuth thruster on a DP operated Vessel needs to be replaced for repair or maintenance purposes. At present these operations are performed either during a dry-dock call or in sheltered waters with the assistance of a shearleg or Heavy Lift Vessel moored alongside the DP operated Vessel. In order to reduce downtime of the DP operated Vessel a clear trend is observed of operations being carried out more offshore and in deeper waters by means of a wet handshake between a Heavy Lift Vessel (HLV) and a DP operated Vessel. To get insight into the workability of such offshore thruster exchange operations it is important to study the dynamic interactions between the bodies involved. This paper describes the development of a methodology which accurately determines the workability of an offshore thruster exchange operation. The methodology is developed by BigLift Shipping, which has performed several thruster exchange operations in sheltered waters in the past few years. Furthermore the results of a workability analysis of a thruster exchange operation offshore Ghana are presented. In order to determine workability, first the hydrodynamic behavior including interaction effects of the coupled configuration of the DP operated Vessel, the Heavy Lift Vessel and the azimuthing thruster is calculated for a range of seastates, which results in the response spectra of the Vessels. Then for each seastate the response is compared with the defined operational criteria to determine whether this seastate is workable, critical or non-workable, which results in a workability diagram. The workability can be quantified by combining this workability diagram with a wave-scatter diagram of the location of interest. In general this is a thoroughly studied topic. In order to achieve a higher level of accuracy of the workability prediction the focus of the methodology described in this paper has been pointed on two aspects that can be of significant influence. • First the persistency of a certain seastate is investigated. In the approach described above any variation of the environmental conditions over the duration of the operation is not considered. The effect of changing weather in time can be of significant influence on the overall workability. In order to take into account persistency information a numerical dataset of 3 hours statistics over a period of 10 years is used. Combining this information with the duration of all consecutive steps of the operation, results in a more realistic workability prediction. Similar approaches in seakeeping of ships are shown by Dallinga et al. (2004) [1], Naito et al. (2006) [2]. • Secondly the influence of a frequency domain approach compared to a time domain approach is analyzed. The nonlinear effects that occur in the coupled configuration of multiple bodies can not be taken into account in the frequency domain approach. Therefore the motion analysis is performed in the time domain. As an example case a thruster exchange operation offshore Ghana has been studied. The results of the study show that the workability prediction based on scatter diagram metocean data is influenced substantially when persistency information of metocean data is taken into account. The effect of the duration and criteria of independent operational steps on the workability are clearly visible in the persistency approach. This enables a to-the-point approach in improving the workability. Although time domain analysis is taking into account nonlinear effects, the difference between time and frequency domain analysis can be neglected for the presently studied configuration.Copyright © 2011 by ASME

Heinen Hopman - One of the best experts on this subject based on the ideXlab platform.