QUALITY OF WIND POWER - Energistyrelsen

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QUALITY OFWIND POWERHow does quality affect thecost of electricity generationfrom wind power?

QUALITY OF WIND POWERWind power is a cornerstone in the greentransition of the power sector, and onshorewind power is in many cases competitivewith power production based on fossil fuels.Nevertheless, it is evident that many windfarms do not perform optimally. This paperillustrates how a consequent focus on quality can help to optimize wind farm energyproduction by a combination of quality inwind turbine design and manufacturing,wind farm project design, and wind farmoperation. This is done by calculating theimpacts on LCoE(Levelized Cost Of Energy) for a number ofexamples with assumptions chosen incooperation with industry experts.LCoE: LEVELIZED COST OF ENERGYLCoE includes both the investment and the operational costs of an energy technology tocalculate the average cost of energy during the lifetime. It also includes external costs suchas emissions, system integration costs, etc. LCoE is often used as a simple way to comparedifferent generation technologies’ socio economic energy production costs. The DanishEnergy Agency has prepared an international LCoE-calculator that can be freely downloaded and used. The tool allows the user to adapt all input data to a local or national context.Wind turbine design and manufacturingWind farm project designDesign,Wind farm operationQuality ofQuality ofManufacturing,Wind Data,O&M concepts,Site Assessment,Load managementsystems,WTG Selection,SCADA systems 2Wind farm Design andInstallationReliable windturbinesOptimised aerodynamic and mechanical performanceOptimized gridperformanceIntegrated O&Msupport Quality ofTraining and skillsSpare parts andsupportSCADA anddiagnostic systemsReliable AEP estimateOptimised arrayefficiencyOptimised rotordiameter and towerheightsVerified turbineloadsOptimized capacityfactor Verified performance and OEMsupportPreventive maintenanceIncreased outputthrough continuousoptimizationsOptimised availability

ABBREVIATIONSO&M: Operation and Maintenance, i.e. thenecessary works to keep the wind farm inoperation, including daily supervision, planned and unplanned maintenance, repairs,administration, etc.SCADA: Supervisory Control and DataAcquisition, i.e. the systems used to monitorand control the wind turbines and the windfarm, and to collect information about theoperation statistics.WTG: Wind Turbine Generator, i.e. the individual wind turbine units, which together withfoundations, cables, etc. forms a wind farm.PC: Power curve, i.e. the relation betweenwind speed in the turbines hub height (inm/s) and the power output (in kW).OEM: Original Equipment Manufacturer, i.e.the company that originally manufacturedthe wind turbine or its components.CFD : Computational Fluid Dynamics, i.e.numerical methods used to simulate theflow over a modelled surface by computercalculations, for example to determine windspeed and turbulences at each plannedturbine position in a wind farm. Especiallyimportant in mountain areas.AEP: Annual Energy Production, i.e. theexpected energy production of the windturbine/wind farm in a year with normalwind conditions.QUALITY IN WIND TURBINEDESIGN AND MANUFACTURINGWind turbines and their components areexposed to high dynamic loading for manyhours in rough climates. Quality in design isa main driver for cost effectiveness over thelifetime. Continuous technical developmentover decades has led to more efficient,reliable, and yet lighter turbines. Among thekey quality issues in design are: Optimization of aerodynamic andmechanical performanceReduced loads and weight, and increasedyields are obtained through the use of advanced methods for load simulations andintegrated design of drive train componentsand control systems. For instance, turbinesof a given platform can have many differentoptional rotor diameters and tower heightsto allow for an optimal choice for varioussite conditions. Similarly, a higher powerrating can be obtained by optimization ofexisting turbine platforms. Optimized grid performanceOptimized grid performance of wind farmsby use of power electronics in combination with wind farm control systems. Forinstance, wind farms can provide activegrid support through abilities for fault ridethrough , active power factor regulation,and gradual ramp-out at high wind speeds.This increases the value of wind in the gridsand minimizes down time. Solutions for improved reliability andoperation and maintenanceDesign for improved reliability and cost-effective operation and maintenance includeuse of full-scale accelerated testing, statistical fault analysis, condition monitoring(vibrations, temperatures etc.), and improved SCADA facilities. This can help to adaptthe design to minimize breakdowns andfacilitate preventive maintenance.In manufacturing, a high focus on qualitycontrol and factory testing of componentsand complete turbine nacelles reducesDanish Energy Agency, Tel: 45 3392 6700, website: www.ens.dk/en 3

QUANTIFICATION OF QUALITYIN WIND TURBINE DESIGN ANDMANUFACTURING FOR LCOECALCULATIONThe calculation assumes that the combination of turbine optimizations result in moreefficient turbines that leads to 10 percenthigher energy yields in average. However,a price increase of the turbines for addingmore advanced options is expected toincrease the overall investment costs by 10percent.down time due to teething and component failures over the lifetime. Test run andcertification of new turbine models helpsto prevent teething problems and obtain ahigh availability.QUALITY IN WIND FARMPROJECT DESIGNQuality in wind farm design is obtainedthrough experience, good planning, and application of best available methods. Amongthe most important issues are: Site assessment and wind dataSufficient and high quality wind data willprovide the basis for assessing the windresource and determine the specific loadbasis for the site, i.e. the wind class according to IEC 61400-1. This ensures that theoptimum turbines can be selected and thatthe turbine loads and energy productioncan be estimated with good accuracy. Selecting the optimal windturbines for the siteTurbines are designed and certified to IECClass that defines the allowable meanand extreme wind speeds and turbulencelevels. For a specific site turbines shall4be selected to optimize rotor diametersand tower heights relative to generatorrating, and thereby maximize the energyproduction and capacity factor withoutcompromising safety and lifetime. Thismust be seen in connection with costs ofother project elements such as transport,installation and foundations. Customizationby calculation of loads at individual turbinepositions allows for a further optimizationof rotor diameters and tower heights than aconservative selection by IEC class. Optimization of the layoutof turbines in the wind farmThe wind farm layout shall be optimized toensure the highest possible array efficiency (i.e. minimize wake losses), and at thesame time ensure that none of the turbinesbecome overloaded.The main tools to obtain quality in windfarm design are state of the art experienceand specialist knowledge in wind measurement and resource estimates, wind farmlay out, and turbine load calculations. Toassist the design and planning a number ofadvanced software solutions exist for windanalysis, dynamic load modelling, CFDmodels, and lay out optimization, which canhelp to maximize energy production andtailor the turbines to the actual sites.QUANTIFICATION OF QUALITY INWIND FARM PROJECT DESIGNFOR LCoE CALCULATIONThe calculation assumes an improvementof array efficiency from 85 percent to 90percent due to optimizations of site layout.Further, an average increase of the annualenergy production of 5 percent is expected because of optimizing the turbines tothe site.

QUALITY IN WINDFARM OPERATIONThe competitiveness of wind power mostdirectly depends on the performance inthe operation phase. The term ‘Availability’expresses the share of the total time forwhich the turbines are able to generate.Today, state of the art wind farms obtainavailabilities above 98%, whereas othersfall far below such levels due to continuousproblems of both technical and organizational nature. However, even when a highavailability is reached, the energy production can be further improved by prioritizinglow wind periods for the planned andnecessary service works. A high qualityin operation and maintenance includesamong other things: Proven performance at taking overIt is vital that the individual turbines, aswell as the overall wind farm control- andSCADA systems, are duly tested and freeof defects when the owner takes over thewind farm. Experience shows that evenminor initial faults and shortcomings canlimit the performance for several years. Training and skills ofthe service providerWind turbine technology of today is advanced and complex. The quality in operationand maintenance directly relies on thestaff’s theoretical and practical skills, bothin terms of basic education and specialisttraining with wind turbines. For long-termservice agreements, it is essential that service providers have full technical capabilities demonstrated by a proven record. Herecounts both the ability to operate the windfarm and solve problems efficiently on adaily basis, as well as the capability to planand carry out major operations. Spare parts and OEM supportA well-integrated spare parts and supportstrategy plays a key role to keep a windfarm in operation. The lack of even smallerparts can be critical to operation. Since allparts cannot be stored on site it becomescrucial to have agreements that secureavailability and short lead times of strategicmain components. Load management systemsand PC optimizationIn operation, continuous improvement ofthe wind farm energy production can beobtained by using analyses of operationalrecords, e.g. of load- and wind data to verifyand optimize the power curve for eachindividual turbine. At the same time loadmanagement systems ensure that lifetime is not compromised. For example, anoverall PC uprating can be combined withautomatic down regulation of turbines inwind directions with high turbulence loads.In addition, turbines can be allowed to operate at reduced output beyond the normalstop-wind.Danish Energy Agency, Tel: 45 3392 6700, website: www.ens.dk/en 5

Use of SCADA and diagnostic systemsTurbine faults and breakdowns often leadto consequential damage and repairs,which take time to plan and carry out,during which no energy will be generated.Best practice use of SCADA systems, including diagnostic systems based on condition monitoring and statistical methods,allows the O&M staff to prioritize and planpreventive maintenance instead of reactingon problems with stopped turbines. Thiscan both limit the costs and increase theavailability.Further, it is evident that, besides the technical and organizational competencies, ahigh commitment and focus on continuousimprovement by both the managementand staff involved with wind farm O&M isessential.Base caseCOST IMPACTS OF QUALITYOF WIND POWERThe table below summarizes the impacts ofquality improvements and optimizations ineach of the three stages of a wind farm project, where the starting point (base case)is a wind farm with poor, but not unrealistically low, performance, and the endpointis a combination of optimization efforts inall stages.In this example it is found that asignificant improvement of the energy yieldexpressed as the yearly full-load hours canQUANTIFICATION OF QUALITYIN WIND FARM OPERATION FORLCOE CALCULATIONThe calculation assumes that a best-inclass O&M performance combined withpower curve optimisations can improvewind farm availability by 3 percent and improve the overall wind farm power curve by3 percent. To achieve these improvementsthe total yearly O&M cost is expected toincrease by 7 percent.Design optimizationsProject design optimizationO&M performanceoptimizationWind Far Availability%95959598Wind Farm Array efficiency%85859090Power curve improvements%1053AEP (Full load Investment costMEuro/MW1,251,371,371,37Yearly O&M costsEuro/MW/Year48.11749.22650.59051.438O&M costsEuro/MWh20,819,417,913,1Life timeDiscount rate6

Example of LCoE in a Low and High Quality Scenario70,066,355,32015-EUR/MWh60,050,040,0System costs30,0O&M costs20,0Capital costTotal LCOE10,0System costsO&M costsCapital costTotal LCOEWind onshore7,820,837,766,3Quality Wind onshore6,317,131,955,3In the calculated example the combined improvements due to quality in turbine design, wind farm projectdesign, and in operation will mean a LCoE reduction of 17 percent even though more expensive turbines wereassumed to increase the investment costs by 10 percent and the overall yearly O&M costs were assumed toincrease by 7 percent.be achieved. However, at the same time amore expensive turbine is selected and theoverall yearly O&M costs are higher.The corresponding effects of the combinedquality of wind optimizations can be calculated using the LCoE-calculator available atthe Danish Energy Agency’s ooperation, and the result appear inthe graphic above. This shows how theimproved performance of the wind turbinesdecreases the LCoE considerably in theQuality Wind scenario, even though theInvestment and the O&M costs are higherin absolute terms.system due to its fluctuations and unpredictable nature. These system costs will varydepending on the actual power system andthe share of wind energy. However, withmore full-load hours and thereby highercapcity factor, the system integration costswill decrease, so wind power has morevalue. Based on Danish model studies,an increase of full load hours as shown inthe example would reduce the integrationcosts from 5.8 EUR/MWh to 4.3 EUR/MWh.Further system costs are the balancingcosts estimated to 2 EUR/MWh.The LCoE calculator also values the systemproperties of the quality wind turbines. Windpower has a reduced value in the energyDanish Energy Agency, Tel: 45 3392 6700, website: www.ens.dk/en 7

The content of this document is prepared byEA Energianalyse in cooperation withindustry experts. The Danish Energy Agency isnot responsible for any content orassumptions presented in this document.The Danish Energy Agency’s Centre forGlobal Cooperation supports emergingeconomies to combine sustainable futureenergy supplies with economic growth. Theinitiative is based on four decades of Danishexperience with renewable energy and energyefficiency, transforming the energy sectors todeploy increasingly more low-carbontechnologies.Learn more on our bal-cooperationFor further information, please contact:Henrik [email protected] 45 3392 7812Jacob Hø[email protected] 45 33 92 67 20Danish Energy Agency,Amaliegade 44, DK 1256 CopenhagenPhone: 45 33 92 67 00website: www.ens.dk/en

turbine/wind farm in a year with normal wind conditions. SCADA: Supervisory Control and Data Acquisition, i.e. the systems used to monitor and control the wind turbines and the wind farm, and to collect information about the operation statistics. PC: Power curve, i.e. the relation between wind