scholarly journals Maintenance Optimization of Offshore Wind Turbines Based on an Opportunistic Maintenance Strategy

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2650 ◽  
Author(s):  
Lubing Xie ◽  
Xiaoming Rui ◽  
Shuai Li ◽  
Xin Hu
Keyword(s):  
Wind Turbines ◽  
Preventive Maintenance ◽  
Weather Conditions ◽  
Offshore Wind ◽  
Maintenance Optimization ◽  
Maintenance Strategy ◽  
Distribution Method ◽  
Opportunistic Maintenance ◽  
Maintenance Costs ◽  
Offshore Wind Turbines

Owing to the late development of offshore wind power in China, operational data and maintenance experience are relatively scarce. Due to the harsh environmental conditions, a reliability analysis based on limited sample fault data has been regarded as an effective way to investigate maintenance optimization for offshore wind farms. The chief aim of the present work is to develop an effective strategy to reduce the maintenance costs of offshore wind turbines in consideration of their accessibility. The three-parameter Weibull distribution method was applied to failure rate estimation based on limited data. Moreover, considering the impacts of weather conditions on the marine maintenance activities, the Markov method and dynamic time window were used to depict the weather conditions. The opportunistic maintenance strategy was introduced to cut down on the maintenance costs through optimization of the preventive maintenance age and opportunistic maintenance age. The simulation analysis we have performed showed that the maintenance costs of the opportunistic maintenance strategy were 10% lower than those of the preventive maintenance strategy, verifying the effectiveness of the proposed maintenance strategy.

An opportunistic maintenance strategy for offshore wind turbine based on accessibility evaluation

2019 ◽  
Vol 44 (5) ◽  
pp. 455-468
Author(s):  
Xie Lubing ◽  
Rui Xiaoming ◽  
Li Shuai ◽  
Hu Xin
Keyword(s):  
Wind Turbine ◽  
Preventive Maintenance ◽  
Wind Farm ◽  
Weather Conditions ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Strategy ◽  
Offshore Wind Farm ◽  
Opportunistic Maintenance ◽  
Operation And Maintenance

The maintenance costs of offshore wind turbines operated under the irregular, non-stationary conditions limit the development of offshore wind power industry. Unlike onshore wind farms, the weather conditions (wind and waves) have greater impacts on the operation and maintenance of offshore wind farm. Accessibility is a key factor related to the operation and maintenance of offshore wind turbine. Considering the impact of weather conditions on the maintenance activities, the Markov method and dynamic time window are applied to represent the weather conditions, and an index used to evaluate the maintenance accessibility is then proposed. As the wind turbine is a multi-component complex system, this article uses the opportunistic maintenance strategy to optimize the preventive maintenance age and opportunistic maintenance age for the main components of the wind turbine. Taking the minimum expectation cost as objective function, this strategy integrates the maintenance work of the key components. Finally, an offshore wind farm is taken for simulation case study of this strategy; the results showed that the maintenance cost of opportunistic maintenance strategy is 10% lower than that of the preventive maintenance strategy, verifying the effectiveness of the opportunistic maintenance.

scholarly journals Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Petri Net ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Major Repair ◽  
Wind Turbine System ◽  
Periodic Maintenance

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.

Controller Design to Reduce Mechanical Fatigue in Offshore Wind Turbines Affected by Ice and Tide

2011 ◽  
Author(s):  
Katherine Faley ◽  
Mario Garcia-Sanz
Keyword(s):  
Wind Turbines ◽  
Controller Design ◽  
Weather Conditions ◽  
Offshore Wind ◽  
Control Technique ◽  
Offshore Wind Turbines ◽  
Mechanical Fatigue ◽  
New Strategy ◽  
Equivalent Mass ◽  
Stiffness And Damping

This paper presents a novel control structure to mitigate the mechanical fatigue in towers of onshore and offshore wind turbines. A general wind turbine dynamic model for both, (1) onshore and (2) offshore systems with the effects of ice and tide is included. These weather conditions further contribute to the uncertainties in the model, most importantly, in the values of tower equivalent mass, stiffness, and damping and increase the amplitude of the velocity of tip-tower vibrations at some particular frequencies, which creates greater mechanical fatigue. A novel control technique to attenuate such a mechanical fatigue is presented in the paper. It is based on the variation of the generator torque in the above rated wind speed region. The control strategy, designed by using Quantitative Feedback Theory (QFT), decreases the velocity of the nacelle movement due to the wind turbulences, thus reducing the associated mechanical fatigue. The new strategy is validated with a realistic nonlinear simulator under a set of different input scenarios and a Monte Carlo method for the uncertainty selection.

scholarly journals Low-Height Lifting System for Offshore Wind Turbine Installation: Modelling and Hydrodynamic Response Analysis Using the Commercial Simulation Tool SIMA

2020 ◽  
Author(s):  
David Vågnes ◽  
Thiago Gabriel Monteiro ◽  
Karl Henning Halse ◽  
Hans Petter Hildre
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Economic Feasibility ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Offshore Wind Turbines ◽  
Lifting System

Abstract With the increasing demand for renewable energy sources in the past years, the interest in expanding the use of wind energy has grown. The next frontier in this expansion process is the use of floating wind turbines offshore. One of the main factors dictating the economic feasibility of such wind turbines is the complexity of their installation process. The dimensions of modern offshore wind turbines, the distance from the installation sites to the coast and demanding environmental factors all contribute to the difficult of developing an efficient installation concept for this kind of structures. In this work, we present a new concept for a catamaran vessel capable of handling the deployment of offshore wind turbines on floating spar platforms using a low-height lifting system that connects to the lower end of the wind turbine. The low-height lifting system is controlled by an active heave compensation system and constant tension tugger wires attached to the turbine mid-section are used to ensure the balance of the tower during the installation process. We conducted a series of hydrodynamic analysis using the software suit SIMA to study the dynamic response of the proposed system under different weather conditions and different operational layouts. This preliminary concept was proven feasible from a hydrodynamic point of view and can now be pushed forward for further studies regarding other aspects of the operation, such as impact and structural loads and mechanical design of components.

Blade Response on Offshore Bottom Fixed Wind Turbines With Down-Wind Rotors

2010 ◽  
Author(s):  
Marit Reiso ◽  
Geir Moe
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Direction ◽  
Offshore Wind ◽  
Simulation Studies ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Numeric Simulation ◽  
Pass Through ◽  
Tower Shadow

Offshore wind turbines are becoming more common due to the scarcity of suitable land sites. By going offshore, maintenance costs become one of the driving expenses. Hence more reliable components should be implemented on offshore wind turbines. The down-wind rotor configuration does not require as powerful yaw drive as the upwind rotor configuration to align with the wind direction. Thus the yaw system can be simpler with fewer components that can fail and require maintenance. This paper presents numeric simulation studies of how the tower shadow impacts the blades when they pass through the wake behind the tower. The work concentrates on bottom-fixed offshore wind turbines designed for the specifications of the NREL offshore 5-MW baseline wind turbine. The blade response has been compared for a full truss tower and a conventional tubular tower to show how the different tower shadows influence the blades. The blades on the more transparent truss tower experience less root flapwise moment fluctuations due to the weaker tower shadow. The simulations were performed by means of GH Bladed, version 3.82.

scholarly journals New perspectives in offshore wind energy

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140228 ◽  
Author(s):  
Giuseppe Failla ◽  
Felice Arena
Keyword(s):  
Renewable Energy ◽  
Wind Turbines ◽  
State Of The Art ◽  
Experimental Studies ◽  
Power Production ◽  
Offshore Wind ◽  
Theme Issue ◽  
Broad Perspective ◽  
Maintenance Costs ◽  
Offshore Wind Turbines

The design of offshore wind turbines is one of the most fascinating challenges in renewable energy. Meeting the objective of increasing power production with reduced installation and maintenance costs requires a multi-disciplinary approach, bringing together expertise in different fields of engineering. The purpose of this theme issue is to offer a broad perspective on some crucial aspects of offshore wind turbines design, discussing the state of the art and presenting recent theoretical and experimental studies.

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