The Theoretical And Technical Research On Maximum Benefit Of Offshore Wind Farm

With the rapid consumption of traditional fossil fuels,such as coal,oil and so on,the demands of a renewable and clean energy are imminent with their storage capacity dring up,the Greenhouse Effect and environmental problems has been increasingly serious.Among the renewable clean energy such as wind,solar,tide and geothermal,wind energy is one of the main sources of environment-friendly power generation.Meanwhile,their generation efficiency is higher and they are competitive with other power generation methods.In recent years,offshore wind farms have become a main object of investment in wind field construction,because offshore wind farms possess the high wind speed,low turbulence,besides that,their area is unrestricted,and they could mitigate the influence of noise on the surrounding environments and reduce the turbine fatigue loads,compared to onshore wind farms.However,the construction of offshore wind farm will bring expensive ocean treatment,installation,operation and maintenance costs,which will greatly reduce the use of renewable energy and hinder the construction of offshore wind farms.In order to maximize the benefits of offshore wind farm,that means minimizing costs of wind farm and maximizing its total annual production power(AEP),the theoretical and technical researches about the wind turbine selection,layout and control have been carried out in this paper.the detail optimization issues and works are as follows:(1)The optimization method of energy cost suitable for a wind turbine selection is proposed,and the accuracy and applicability of the method are studied and analyzed.Energy cost refers to the ratio of wind farm costs to AEP,and this method is widely applied to study the benefits of wind farm.The accuracy and applied fields of the existed wind turbine selection methods decreases for simplifying the cost mod els and ignoring the variation of wind speed at different hub heights,and even it applied to specific wind farms.In viewing the shortcomings of the above methods,an accurate energy cost model which reflecting the variation of wind resources and wind turbine parameters is proposed,and then an iterative method for calculating the optimal energy cost is proposed.The simulation results show that the proposed method based on the energy cost model can select the appropriate type of turbine which corresponding to maximizing the economic efficiency of offshore wind farm,no matter whether it is applied to wind farms with random or specific wind speed.This method could provide more ideal data of wind turbine for developers on pre-stage.(2)An energy cost model considering wind turbine and optimization wind farm layout is developed,which based on the proposed energy cost model which is related to COE of single wind turbine.In lots of researches,a wind turbine energy cost model is used to replace the whole wind field energy cost model,which ignore the influence of wake effect and wind field layout.This method reduce d the complexity and simplified the computational difficulty.In order to build up an accuracy energy cost model,firstly,the total cost function which based on NREL cost model is improved by considering wake effect and wind resource,and AEP is revised by optimizing the wind farm layout which adopting efficient optimization algorithm and optimization strategy.Considering the factors of wind turbine selection,cost,layout and wind resource distribution,this paper makes a detailed analysis and researche s on maximum benefit of offshore wind farm from the two aspects: theory and technology.(3)An exhaustive method for achieving maximum the active p ower output in fixed wind turbine layout is proposed.Typically,a single wind turbine uses maximum power point tracking to maximize power output.However,in the wind farm,the downstream wind turbine is affected by the wake effect of the upstream wind tu rbine,and its active power output is significantly reduced.In this chapter,the tip speed ratio and the pitch angle of the upstream wind turbine are optimum control,which would result in the wake distribution of upstream wind turbine changed.Thus,the loss of active power is reduced,the sum of the active power in offshore wind farm would maximize.(4)The research on the wind farm layout and control in offshore wind farm for selected turbine is carried out.In order to solve the problem about the big a nd complex calculation from the exhaustive method in offshore wind farm,the coordinated control method about a clustering and grouping is proposed.Firstly,according to different wind directions,the wind turbines in the wind farm are divided into regions to ensure the same inflow speed and wake flow field of the wind turbine in the same region.Then,the exhaustive method is used to optimize the individual wind turbines in different regions,so that the same parameters about the tip speed ratio and the pitch angle in same group of wind turbine can be adopted.Finally,the maximum total active power output in offshore wind farm can be realized.This paper aims at maximizing economic benefit in offshore wind farm,so the systematically studies about wind turbine selection,layout and control are carried out,the results reveal the influence of wind turbine type and location layout on wind farm cost.At the same time,it also shows the inherent mechanism of wind turbine location layout and control to maximize wind farm productivity.In a word,the proposed methods provide a theoretical and technical basis for to build up offshore wind farms.