STANDARDDNVGL-ST-0437Edition November 2016Loads and site conditions for wind turbinesThe electronic pdf version of this document found through http://www.dnvgl.com is the officially binding version.The documents are available free of charge in PDF format.DNV GL AS
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Changes – currentCHANGES – CURRENTGeneralThis is a new document.Standard, DNVGL-ST-0437 – Edition November 2016DNV GL ASPage 3
CHANGES – CURRENT . 3Sec.1Sec.2Sec.3Introduction . 81.1General.81.2Objectives .81.3Scope and application .91.4Normative references .91.5Informative references.101.6Terminology .111.7Acronyms, abbreviations and symbols .121.7.1 Acronyms and abbreviations. 121.7.2 Symbols . 131.7.3 Greek symbols. 16External conditions . 182.1Fundamentals.182.1.1 Relevant types of external conditions. 182.1.2 External conditions for turbine types and wind farm sites . 182.1.3 Consideration of external conditions in the design . 182.2Wind turbine classes .192.2.1 Wind data for turbine classes. 192.2.2 Wave data for offshore wind turbine classes . 202.2.3 Wind turbine classes. 202.3Wind conditions.222.3.1 General . 222.3.2 Offshore normal turbulence model. 222.3.3 Offshore extreme turbulence model . 242.4Marine conditions for offshore wind turbines .242.4.1 General . 242.4.2 Wave climate . 252.4.3 Wind-wave misalignment . 252.4.4 Reference sea states and wave heights . 252.4.5 Wave modelling . 262.4.6 Wave theories and wave kinematics . 312.4.7 Breaking waves . 312.4.8 Sea currents . 322.4.9 Sea level, bathymetry . 332.4.10 Sea ice . 342.4.11 Marine growth . 352.5Other environmental conditions .362.5.1 General . 362.5.2 Other environmental conditions . 372.5.3 Extreme temperatures . 372.5.4 Atmospheric ice formation. 372.5.5 Earthquakes . 382.5.6 Wind farm influence . 382.5.7 Soil properties . 382.5.8 Risk analysis . 392.5.9 Sea bed and scour . 392.5.10 Electrical power network conditions . 39Determination of site specific design conditions . 40Standard, DNVGL-ST-0437 – Edition November 2016DNV GL ASPage 4ContentsContents
Sec.4General.403.1.1 External conditions. 403.1.2 Wind farm location data . 413.2Methods for determining site specific meteorological designconditions .413.2.1 General . 413.2.2 Meteorological data bases . 413.2.3 Meteorological measurements. 413.2.4 Numerical methods . 423.3Determination of meteorological data .423.3.1 General . 423.3.2 Turbulence intensity . 433.3.3 Extreme wind extrapolation . 433.4Site specific marine conditions .443.4.1 General . 443.4.2 Wave data . 453.4.3 Current data . 463.4.4 Water level data . 463.4.5 Sea ice . 463.4.6 Marine growth . 463.4.7 Seabed movement and scour. 463.5Determination of other environmental conditions .463.5.1 Foundation/soil properties . 463.5.2 Influence of earthquakes. 473.5.3 Complex terrain . 473.5.4 Corrosive and/or abrasive effects . 483.5.5 Electrical network conditions . 483.5.6 Weather window and weather down time . 48Calculation of loads . 494.1Fundamentals.494.1.1 General . 494.1.2 Assessment documents. 494.1.3 Design methods. 514.1.4 Safety classes . 514.2Calculation of loads .514.2.1 General . 514.2.2 Loads . 524.2.3 Operational loads . 524.2.4 Inertia and gravitation loads. 534.2.5 Aerodynamic loads . 534.2.6 Hydrodynamic loads . 544.2.7 Hydrostatic loads . 594.2.8 Sea ice loads . 594.2.9 Seismic loads . 604.2.10 Boat impact loads . 604.2.11 Combination of external conditions . 624.2.12 Combination of loads . 624.2.13 Load impact due to extreme temperatures . 624.2.14 Variation of support structure natural frequency and operationwithin the resonance range . 624.2.15 Load-relevant control and safety system functions. 624.2.16 Other loads . 634.3Partial safety factors for loads .63Standard, DNVGL-ST-0437 – Edition November 2016DNV GL ASPage 5Contents3.1
126.96.36.199.188.8.131.52.5Sec.5Partial safety factors for the loads in the analysis of the ultimatelimit state/ultimate strength . 64Partial safety factors in the analysis of the fatigue limit state/fatiguestrength . 64Partial safety factors in the analysis of the accidental limit states. 64Serviceability limit states . 64Special partial safety factors. 654.4Load case tables for onshore and offshore loads .654.5Design situations and load cases for wind turbines .694.5.1 Power production (DLC 1.1 to 1.7) . 694.5.2 Power production plus occurrence of fault (DLC 2.1 to 2.5) . 704.5.3 Start-up (DLC 3.1 to 3.3). 714.5.4 Normal shut-down (DLC 4.1 and 4.2) . 714.5.5 Emergency shut-down (DLC 5.1). 724.5.6 Parked (DLC 6.1 to 6.5) . 724.5.7 Parked plus fault conditions (DLC 7.1 and 7.2) . 734.5.8 Transport, installation, maintenance and repair (DLC 8.1 to 8.5) . 744.5.9 General influences . 754.5.10 Operational influences . 764.6Design load cases for extended design situations .764.6.1 Drifting sea ice (DLC 9.1 to 9.5). 794.6.2 Temperature effect (DLC 10.1 and 10.2) . 794.6.3 Earthquakes (DLC 11.1 to 11.3). 794.6.4 Wind farm influence (DLC 12.1) . 794.7Evaluation of loads .794.7.1 General . 794.7.2 Evaluation of load cases applying deterministic gusts . 804.7.3 Evaluation of load cases applying turbulent wind . 804.7.4 Evaluation of DLC 1.1 and DLC1.3 . 804.8Site specific evaluation .814.8.1 Site specific evaluation through comparison of site wind conditionsand design class conditions . 814.8.2 Site specific evaluation through load calculations. 82Measurements. 845.1General.845.2Requirements for the wind turbine to be tested .845.3Power curve measurements .855.4Load measurements .855.4.1 Measurement of mechanical loads according IEC 61400-13. 855.4.2 Verification of design loads via model verification by comparingsimulation and measurement results . 85App. A Coordinate systems. 87App. B Statistical extrapolation procedure .
wind turbines are identical to those in IEC 61400-1, wh ereas marine conditions are covered in depth in this standard and refer partly to IEC 61400-3. Sec.3 covers site conditions and requirements for determin ing site specific design conditions as part of the design basis.