Maintenance Decision Modeling And Optimization Research For Wind Farm And Wind Turbines

Owing to the shortage of fossil fuels and environmental deterioration,people‘s global environmental protection awareness has been increased,and the renewable energy has gained wide attention.Wind power is considered as one of the inexhaustible sources of the clean energy for electricity generation and has achieved a milestone development in the past few decades due to its low cost and pollution-free advantages.The significant reductions in energy cost and the potential as a source of electricity demand has amply demonstrated that the wind power will continue to grow strongly for decades.However,wind farms are generally located in remote areas or offshore districts,and the high operational and maintenance costs due to adverse condition pose challenges for the wind industry.Therefore,to improve the economic benefit and market competitiveness of wind farms and considering the problems,such as the high maintenance costs due to the huge complex structure,poor conditions,the practical maintenance effectiveness is not easy to evaluate,the inevitable energy production stoppage caused by the intermittent wind speed,and so on,this paper present a systematic research from two dimensions of wind farm and wind turbines considering the strong economic dependence among wind turbines,and the main innovative studies are as follows:(1)From the perspective of a multi-device parallel system,the maintenance decision modeling and optimization of the wind farm is researched.The individual wind turbine is considered as an independent device,and the whole wind farm can be reviewed as a parallel system with multiple devices,and the queuing theory framework is used to construct the group maintenance decision model for the wind farm from two levels of the fixed failure rate and the variable failure rate.(2)The expression of the imperfect maintenance effectiveness of a repairable system and the periodic imperfect preventive dynamic maintenance decision model for wind turbine are studied.Considering the maintenance effectiveness for repairable systems are typically imperfect,the observable factors affecting the imperfect maintenance effectiveness of system are analyzed according to the operational and maintenance characteristics of system,and a failure rate function update model is constructed.In light of this model,a preventive dynamic maintenance strategy with imperfect maintenance effectiveness for wind turbines is proposed.(3)The dynamic imperfect group maintenance decision modeling and optimization for wind farm system is researched.On the basis of the group maintenance framework and the failure rate function update model proposed before,a dynamic group maintenance decision model is presented for a wind farm.The validity and effectiveness of the proposed model have been verified by the numerical experiment and example analysis.(4)The problem upon the condition group maintenance decision modeling and optimization for a wind farm system is studied.Using the condition monitoring technology,and the method of constructing the condition group maintenance for wind farm are further discussed based on the constructed group maintenance model before.In this process,a stationary probability density function is derived by analyzing all of the possible maintenance scenarios at each maintenance decision point,and this solves problem of the maintenance correlation between devices.(5)An external opportunistic maintenance strategy for wind turbines is proposed considering the influence of the intermittent wind speed.The intermittence of random wind speed leads to the inevitable production interruption,which provides an external opportunity for the device maintenance.This opportunity is used to study the condition maintenance decision model for a wind turbine from two aspects,i.e.the normal operation and the external opportunity condition,and the economic advantage of the proposed model is demonstrated by the numerical analysis.(6)The internal and external joint opportunities maintenance decision modeling and optimization for a wind turbine is studied.On the basis of the external opportunity maintenance decision model discussed above,the internal opportunity provided by a failed turbine is integrated.The case study results show that the model can allocate the maintenance resources reasonably and the optimal economic benefit of wind turbine can be achieved.