DEPENDABILITY OF OFFSHORE  WIIND TURBIINES
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

DEPENDABILITY OF OFFSHORE WIIND TURBIINES

on

  • 506 views

In recent years more and more demanding structures are designed, built and operated ...

In recent years more and more demanding structures are designed, built and operated
to satisfy the increasing needs of the Society. This kind of structures can be denoted
as complex ones. Among large constructions arrangements, Offshore Wind Turbines
(OWT) are definitely complex structural systems, being this complexity related to
different aspects such as hard nonlinearities, wide uncertainties and strong
interactions, either among the single parts or between the whole structure and the
design environment.
On the whole, the quality of a complex system is denoted by the idea of
dependability, while for a structure the performances are connected to the property of
structural integrity, considered as the completeness and consistency of the structural
configuration. Even if these concepts have been originally developed, respectively, in
computer science and for aerospace applications they can be applied to other high
performance systems as OWT.
The present paper will show some specific aspects of the modern approach
for the design and the analysis of complex structural systems. In the first part of the
paper, the general aspects are recalled like the System Engineering approach and the
Performance-based Design. Attention is devoted to some important aspects, such as
the structure breakdown and the safety and performance allocations. In the second
part of the paper, a basic application of the concepts introduced is presented.

Statistics

Views

Total Views
506
Views on SlideShare
506
Embed Views
0

Actions

Likes
0
Downloads
4
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

DEPENDABILITY OF OFFSHORE WIIND TURBIINES Presentation Transcript

  • 1. DEPENDABILITY OF OFFSHOREDEPENDABILITY OF OFFSHOREWIND TURBINESWIND TURBINESFranco Bontempi, Marcello Ciampoli, Stefania ArangioUniversity of RomeUniversity of Rome ““La SapienzaLa Sapienza””Department ofDepartment ofStructural and Geotechnical EngineeringStructural and Geotechnical EngineeringHonolulu, March 17th 2010
  • 2. OUTLINEOUTLINEConclusionsConclusionsConclusionsConclusionsConclusionsSystem approach for structural engineering applicationsIntroductionIntroductionIntroductionIntroductionThe concept of dependabilityPartIPartIPartIPartIPartIIPartIIPartIIPartIIApplication to an offshore wind turbine support structureBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 3. Definition of structureStefania Arangio - Structural integrity monitoring of long span bridges using adaptive models“device for channeling loads that results from the use and/or presence of thebuilding to the ground”STRUCTUREThis definition does not consider some important aspects:INTERACTION AMONGDIFFERENTSTRUCTURAL PARTSINTERACTIONBETWEEN THEWHOLE STRUCTURESAND THE DESIGNENVIRONMENTInteractions arecharacterized bynonlinearities anduncertaintiesCOMPLEXITY
  • 4. Structure vs. Structural SystemSTRUCTURESYSTEM APPROACHSTRUCTURALSYSTEM“a set of interrelatedcomponents workingtowards a commonpurpose”INTERACTION AMONGDIFFERENTSTRUCTURAL PARTSINTERACTIONBETWEEN THEWHOLE STRUCTURESAND THE DESIGNENVIRONMENTInteractions arecharacterized bynonlinearities anduncertaintiesCOMPLEXITYBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 5. NASA System complexityBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 6. Structure vs. Structural SystemStefania Arangio - Structural integrity monitoring of long span bridges using adaptive modelsSTRUCTURALDECOMPOSITIONBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesSYSTEM APPROACHSTRUCTURALSYSTEMINTERACTION AMONGDIFFERENTSTRUCTURAL PARTSINTERACTIONBETWEEN THEWHOLE STRUCTURESAND THE DESIGNENVIRONMENTInteractions arecharacterized bynonlinearities anduncertaintiesCOMPLEXITY
  • 7. Structural decompositionBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 8. OWT Structural decompositionSCALEDETAILLEVELFINITEELEM.SYSTEM LEVEL MACRO LEVEL MESO-LEVEL MICRO-LEVELWind farm Single turbine Single turbineIndividualcomponentsIdealized modelcomponentsApproximateshape of thecomponentsDetailedshape of thecomponentsDetailed shape ofthe connectionsBLOCK elements BEAM elements SHELL andSOLID elementsSHELL andSOLID elements
  • 9. OUTLINEOUTLINEBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesSystem approach for structural engineering applicationsIntroductionIntroductionIntroductionIntroductionThe concept of dependabilityPartIPartIPartIPartIPartIIPartIIPartIIPartIIApplication to an offshore wind turbine support structure
  • 10. How is possible to define (and measure ) the quality of complex structuralsystems as the OWT farms?We need a concept able to take properly into account the different aspectsrelated to conceptual and structural design, construction and maintenanceduring the whole lifetime.DEPENDABILITYIt is a global concept that describes the aspects assumed as relevant withregards to the quality performance and its influencing factors (Bentley,1993)In rigorous terms, the dependability of a system reflects the user’s degree oftrust in that system, i.e. the user’s confidence that the system will operate asexpected and will not “fail” in normal use (Sommerville, 2000): the systemshall give the expected performance during the whole lifetimeDependability (1)Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 11. Dependability (2)DEPENDABILITYOF STRUCTURALSYSTEMSMEANSTHREATSATTRIBUTESObjective measure of thedependabilityThings that can underminethe dependabilityWays to improve thedependabilityBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 12. AvailabilityIntegritySafetyReliabilityMaintainabilitySecurityHigh level/ ActiveperformanceLow level/ PassiveperformanceAttributes of the dependabilityATTRIBUTESBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 13. ReliabilityReliability: the system capacity of failure-free operation over aspecified time in a given environment for a given performance(can be expressed quantitatively by a probability … )AvailabilityAvailability: the system capacity (or readiness) at a point in timeof being operational and able to perform as required (can beexpressed quantitatively by a probability … )MaintainabilityMaintainability: the system attribute concerned with the ease ofrepairing the system after a failure has been discovered orimproving the system to include new featuresActive performanceBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 14. IntegrityIntegrity: absence of alterations of structural response (related tothe completeness and consistency of the structural configuration)SafetySafety: is a property of the system that reflects its ability tooperate, normally or abnormally, without danger of causinghuman injury or death and without damage to the system’senvironment (safety-related prescriptions usually excludeundesirable situations, rather than specify requiredperformances)SecuritySecurity: The system property that reflects the system’s ability toprotect itself from accidental or deliberate external attack(robustnessrobustness)Passive performanceBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 15. Reliability and safety are related but distincto In general, reliability (and availability) is necessary but not sufficientcondition for system safetyo Reliability is concerned with conformance to a given specification for agiven performanceo Safety is concerned with ensuring system cannot cause damageirrespective of whether or not it conforms to its specificationReliabilityReliability SafetySafetySecuritySecurityIt is an essential pre-requisite for availability, reliability and safety.Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 16. FailureFaultErrorPermanent interruption of the systemability to perform a required functionunder assigned operating conditionsTHREATS The system is in an incorrect state: itmay or may not cause failureDefect that represents a potentialcause of error, active or dormantFault managingFault detectionFault diagnosisMEANSFault tolerantdesignInverse problems
  • 17. ATTRIBUTESTHREATSMEANSRELIABILITYFAILUREERRORFAULTFAULT TOLERANTDESIGNFAULT DETECTIONFAULT DIAGNOSISFAULT MANAGINGDEPENDABILITYofSTRUCTURALSYSTEMSAVAILABILITYSAFETYMAINTAINABILITYpermanent interruption of a system abilityto perform a required functionunder specified operating conditionsthe system is in an incorrect state:it may or may not cause failureit is a defect and represents apotential cause of error, active or dormantINTEGRITYways to increasethe dependability of a systemAn understanding of the thingsthat can affect the dependabilityof a systemA way to assessthe dependability of a systemthe trustworthinessof a system which allowsreliance to be justifiably placedon the service it deliversSECURITYHigh level / activeperformanceLow level / passiveperformanceATTRIBUTESTHREATSMEANSMEANSRELIABILITYRELIABILITYFAILUREERRORFAULTFAULT TOLERANTDESIGNFAULT TOLERANTDESIGNFAULT DETECTIONFAULT DETECTIONFAULT DIAGNOSISFAULT DIAGNOSISFAULT MANAGINGFAULT MANAGINGDEPENDABILITYofSTRUCTURALSYSTEMSAVAILABILITYSAFETYMAINTAINABILITYpermanent interruption of a system abilityto perform a required functionunder specified operating conditionsthe system is in an incorrect state:it may or may not cause failureit is a defect and represents apotential cause of error, active or dormantINTEGRITYways to increasethe dependability of a systemAn understanding of the thingsthat can affect the dependabilityof a systemA way to assessthe dependability of a systemthe trustworthinessof a system which allowsreliance to be justifiably placedon the service it deliversSECURITYHigh level / activeperformanceLow level / passiveperformanceDependabilityBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 18. Analysis and design of complex structural systemsStefania Arangio - Structural integrity monitoring of long span bridges using adaptive modelsSTRUCTURALSYSTEMINTERACTION AMONGDIFFERENTSTRUCTURAL PARTSINTERACTIONBETWEEN THE WHOLESTRUCTURE AND THEDESIGN ENVIRONMENTInteractions arecharacterized by strongcharacter, nonlinearityand uncertaintyCOMPLEXITYDECOMPOSITIONSTRATEGYSYSTEMAPPROACHQUALITYON THE WHOLEFOR THESTRUCTURALSYSTEM:DEPENDABILITYATTRIBUTESTHREATSMEANSSTRUCTURAL INTEGRITYPERFORMANCEBASED DESIGNIntroductionIntroductionPartIPartIPartIIPartIIConclusionConclusionss
  • 19. OUTLINEOUTLINEBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines1/31System approach for structural engineering applicationsIntroductionIntroductionIntroductionIntroductionThe concept of dependabilityPartIPartIPartIPartIPartIIPartIIPartIIPartIIApplication to an offshore wind turbine support structure
  • 20. Progressive loss of structural integrity105m35m• Water level: 35 m• Heigth of the structureabove water level:105 m• Pile length under sea bed• Steel 355•Turbine 5/6 MWFor wind farms with a lot ofstructures it is interesting toinvestigate the ability of thesystem to sustain further levels ofdemand after the ULS up toextreme loading conditionsBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesIntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 21. Description of the analysis (1)The survivability of the system is investigated allowing large damage developinginside the structural system: the spread of the plasticity is allowed until the lastconfiguration of equilibrium is reachedNon linear analysis:-Material plasticity-Large displacementsInteger structure (ULS) Loss of structural integrityλ = 1.00 λ = 1.44
  • 22. Increase of damage from the reference baseline ULS configuration tothe last equilibrium configurationλ = 1.44λ = 1.00 λ = 1.32λ = 1.10Description of the analysis (2)Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 23. Measuring the loss of integrity1st freq2nd freq3rd freqA quantitative measure canbe obtained considering themodal behaviorLoad multiplierFrequencies
  • 24. OUTLINEOUTLINEBontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbinesSystem approach for structural engineering applicationsIntroductionIntroductionIntroductionIntroductionThe concept of dependabilityPartIPartIPartIPartIPartIIPartIIPartIIPartIIApplication to an offshore wind turbine support structure
  • 25. ConclusionsOffshore wind turbines (OWT) are complex structural systemsTheir complexity is related to:- nonlinearities- uncertainties- interaction between the parts- interaction between the whole structure and the environmentaldesignUniversity of Rome “La Sapienza”A global concept is needed to the define the quality of the OWTin a comprehensive wayDEPENDABILITY
  • 26. Conclusions (2)The concept of dependability has been applied to OWT supportstructures to investigate the survivability of the system inpresence of extreme actionsUniversity of Rome “La Sapienza”λ = 1.44λ = 1.00The increasing of damage fromthe reference ULS configurationhas been considered by means ofthe load multiplier and consideringthe modal behavior of the structure