1、 Guidance Notes on Global Performance Analysis for Floating Offshore Wind Turbine Installations GUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS FEBRUARY 2014 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Co
2、pyright 2014 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA ii ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 Foreword Foreword The Guidance Notes contained herein should be used in conjunction with the ABS
3、Guide for Building and Classing Floating Offshore Wind Turbine Installations (FOWTI Guide). These Guidance Notes provide suggested global performance analysis methodologies, modeling strategies and numerical simulation approaches for floating offshore wind turbines. These Guidance Notes do not set a
4、dditional design requirements and criteria other than those specified in the FOWTI Guide, and should be used as a supporting document to the FOWTI Guide. These Guidance Notes become effective on the first day of the month of publication. Users are advised to check periodically on the ABS website www
5、.eagle.org to verify that this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be sent electronically by email to rsdeagle.org. ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 iii Table
6、 of Contents GUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS CONTENTS SECTION 1 Introduction 1 1 General . 1 3 Applications . 1 5 Terms and Definitions . 1 5.1 Terminology . 1 5.3 Abbreviations . 6 7 References 6 SECTION 2 Characteristics of Floating Of
7、fshore Wind Turbines 8 1 General . 8 3 Floating Support Structures 8 3.1 TLP-Type Floating Support Structures 8 3.3 Spar-Type Floating Support Structures . 9 3.5 Column-Stabilized (Semi-submersible) Floating Support Structures 10 3.7 Other Types of Floating Support Structures 10 5 Stationkeeping Sys
8、tems . 10 5.1 General 10 5.3 Catenary Moorings 11 5.5 Taut Moorings . 11 5.7 Tendons 11 7 RNA and Control and Safety Systems 12 9 Coupling Effects 12 9.1 General 12 9.3 Aero-elastic Coupling 12 9.5 Aero-control Coupling 12 9.7 Tower-Hull and Mooring Coupling . 12 9.9 Hull-Mooring Coupling . 13 9.11
9、Other Coupling 13 TABLE 1 Representative Natural Periods of Typical FOWT Floating Support Structures 8 iv ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 SECTION 3 Modeling of Floating Offshore Wind Turbines . 14 1 General . 14 3 Modeling of th
10、e Hull 14 3.1 Hydrostatic Loads 14 3.3 Wave Loads on the Large-Volume Floating Hull . 15 3.5 Wind Loads, Current Loads and Hull VIM 16 3.7 Instability 16 5 Modeling of Flexibility of Tower 16 7 Modeling of Stationkeeping System . 16 7.1 General 16 7.3 Mooring Line Nonlinearity 17 7.5 Finite Element
11、Analysis Approach . 17 9 Modeling of Dynamics of Drive Trains 18 11 Modeling of Rotor Blade and Control and Safety Systems 18 11.1 General 18 11.3 Gravitational and Inertia Loads 18 11.5 Aerodynamic Loads . 19 11.7 Actuation Loads (Operational Loads) 19 13 Modeling of Wind Farm Wake Effects 20 15 El
12、ectrical Cable Considerations 20 SECTION 4 Determination of Environmental Loads 21 1 General . 21 3 Aerodynamic Loads on RNA . 21 5 Typical Environmental Loads on Mooring Lines . 21 5.1 Current Induced Loads 21 5.3 Ice-induced Loads . 22 5.5 Vortex-induced Vibrations of the Mooring Lines 22 5.7 Dire
13、ct Wave Loads on Mooring Lines 22 5.9 Marine Growth . 22 7 Typical Environmental Loads on Floating Support Structures 22 7.1 Wind Loads 22 7.3 Wave Loads . 23 7.5 Current Loads 23 7.7 Marine Growth . 23 7.9 Vortex-Induced Motions (VIM) of the Floating Support Structure 24 7.11 Directional Distributi
14、on . 24 9 Ice and Snow Accumulation Induced Loads . 24 11 Earthquake Loads . 24 13 Ice Loads . 25 SECTION 5 Definition of Analysis Methodologies . 26 1 Frequency-Domain and Time-Domain Analysis . 26 1.1 Frequency-Domain Analysis 26 1.3 Time-Domain Analysis . 26 1.5 Combined Time-Domain and Frequency
15、-Domain Analysis . 27 ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 v 3 Quasi-Static and Dynamic Analysis 27 3.1 Quasi-Static Analysis 27 3.3 Dynamic Analysis 27 5 Coupled, Semi-Coupled, and Uncoupled Analysis . 28 5.1 Coupled Analysis . 28 5
16、.3 Semi-Coupled Analysis . 28 5.5 Uncoupled Analysis . 28 SECTION 6 Global Motion Analysis 29 1 General . 29 3 Static and Mean Responses . 29 5 Low Frequency Motions 30 7 Wave Frequency Motions . 30 9 High Frequency Motions . 30 11 Tower and Turbine RNA Load Induced Vibrations . 30 13 Damping 30 13.
17、1 Damping of Low Frequency Motions . 30 13.3 Damping of High Frequency Motions 31 15 Analysis Methods 31 15.1 Frequency-Domain Approach 31 15.3 Time-Domain Approach. 32 15.5 Combined Time-Domain and Frequency-Domain Approach. 32 SECTION 7 Air Gap Analysis 33 1 General . 33 3 Air Gap Analysis Methods
18、. 33 3.1 Frequency-Domain Analysis 33 3.3 Time-Domain Analysis 33 3.5 Combined Time-Domain and Frequency-Domain Analysis . 34 3.7 Other Considerations 34 SECTION 8 Mooring Strength Analysis 35 1 General . 35 3 Mooring Strength Analysis Methods . 35 3.1 Frequency-Domain Analyses for Spread Mooring Sy
19、stems 36 3.3 Frequency-Domain Analyses for Single Point Mooring Systems . 36 3.5 Time-Domain Analyses . 36 3.7 Combined Time-Domain and Frequency-Domain Analyses 36 3.9 Maximum and Minimum Tendon Tensions 37 5 Suggested Time-Domain Analysis Procedure 37 7 Design Checks 37 9 Line Length and Geometry
20、Constraints 37 11 Anchor Forces . 38 vi ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 SECTION 9 Mooring Fatigue Analysis 39 1 General . 39 3 T-N Curve 40 5 Accumulated Fatigue Damage 40 7 Time-Domain Fatigue Analysis Method 41 9 Frequency-Dom
21、ain Fatigue Analysis Method . 41 11 Tendon Fatigue Analysis 41 13 Fatigue Design Checks . 42 SECTION 10 Suggestions for Numerical Simulations . 43 1 General . 43 3 Time Step 43 5 Initial Transient Response 43 7 Wind Generation and Grid Size 44 9 Simulation of Wave Conditions . 44 11 Flexibility of R
22、NA and Tower . 45 13 Simulation Length and Number of Random Seeds 45 15 Analysis Methods and Tools . 47 TABLE 1 Adjustment of Wind Conditions with Different Averaging Time Durations 44 TABLE 2 Adjustment of the Significant Wave Height . 45 TABLE 3 Suggested Minimum DOFs for Modeling Flexibility of t
23、he RNA and the Tower. 45 TABLE 4 Suggested Simulation Time Duration and Number of Random Seeds for the DLCs 47 TABLE 5 Suggested Analysis Methods for the DLCs 48 ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 1 Section 1: Introduction SECTION
24、1 Introduction 1 General Global performance analyses determine the global effects of environmental conditions and other loads on the Floating Offshore Wind Turbine (FOWT) and its components including the tower, hull structure, mooring lines or tendons, anchors, export electrical cable, etc. Global p
25、erformance analyses should be carried out for all critical conditions in the pre-service and in-service phases, represented by the design load conditions specified in Chapter 5, Section 2 of the ABS Guide for Building and Classing Floating Offshore Wind Turbine Installations (FOWTI Guide). Because s
26、ignificant interactions could occur among the Rotor-Nacelle Assembly (RNA) and control system, the floating support structure and the stationkeeping system, an integrated (coupled) model including all these components is recommended to be used for global performance analyses. An alternative method,
27、where the dynamic analyses of the stationkeeping system are performed separately by using the responses of the floating support structure as boundary conditions, may also be acceptable, provided that the coupling effect of the stationkeeping system and the floating support structure is adequately ta
28、ken into account. The global performance analysis software should have the capability of considering complex interactions among aerodynamic loads, hydrodynamic loads, actions of turbine safety and control systems and structural dynamic responses of the FOWT. The analysis procedures should reflect th
29、e application limits of the selected software. Both publically available, industry-recognized software and in-house software may be used for the analyses. However, in-house software has to be adequately calibrated against model tests, field tests or the industry-recognized software. General guidance
30、 on global performance analyses of the floating support structure and the stationkeeping systems can be found in: ABS Rules for Building and Classing Floating Production Installations (FPI Rules), API RP 2T, API RP 2FPS and ISO 19904-1 for the design of floating offshore structures API RP 2SK, API R
31、P 2SM and ISO 19901-7 for catenary mooring and taut leg mooring systems. API RP 2T for TLP tendon systems. References are also made to other appropriate ABS Rules, Guides and Guidance Notes such as those listed in Subsection 1/7. 3 Applications These Guidance Notes provide global performance analysi
32、s methodologies, modeling strategies and suggestions for numerical simulations for FOWTs. These Guidance Notes do not set additional design requirements and criteria other than those specified in the FOWTI Guide, and should be used as a supporting document to the FOWTI Guide. The global performance
33、analysis guidelines provided in these Guidance Notes are only applicable to FOWTs. 5 Terms and Definitions 5.1 Terminology 5.1.1 Added Mass Effective addition to system mass, which is proportional to the mass of displaced water. 5.1.2 Air Gap Clearance between the highest water surface that occurs d
34、uring design environmental conditions and the lowest exposed structures not designed to withstand wave impingement. Section 1 Introduction 2 ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBINE INSTALLATIONS .2014 5.1.3 Catenary Mooring Mooring system where the restori
35、ng action is provided by the distributed weight of mooring lines. 5.1.4 Cut-In Wind Speed (Vin) The lowest 10-minute mean wind speed at Hub Height at which the wind turbine starts to produce power in the case of steady wind without turbulence. 5.1.5 Cut-Out Wind Speed (Vout) The highest 10-minute me
36、an wind speed at Hub Height at which the wind turbine is designed to produce power in the case of steady wind without turbulence. 5.1.6 Design Life Assumed period for which a structure, a structural component, a system or equipment is expected to be used for its intended purpose with anticipated mai
37、ntenance, but without substantial repair being necessary. 5.1.7 Dip and Thrash Zone A chain or wire rope section above and close to the seafloor that may touch the seabed due to the motions of the Floating Support Structure. 5.1.8 Dynamic Positioning (DP) Stationkeeping technique primarily using a s
38、ystem of automatically controlled on-board thrusters to generate appropriate thrust vectors to counter the environmental actions and maintain an intended position within prescribed tolerances. 5.1.9 Emergency Shutdown Rapid shutdown of the wind turbine triggered by a protection function or by manual
39、 intervention. 5.1.10 Floating Offshore Wind Turbine (FOWT) Wind Turbine consisting of the Rotor-Nacelle Assembly (RNA), the Floating Support Structure and the Stationkeeping System. 5.1.11 Floating Offshore Wind Turbine Installation (FOWTI) A Floating Offshore Wind Turbine Installation encompasses
40、three principal areas: the Floating Support Structure (see 1/5.1.12) for carrying the wind turbine RNA (see 1/5.1.33), the Stationkeeping System (see 1/5.1.43) and the onboard machinery, equipment and systems that are not part of the RNA. In these Guidance Notes, the Floating Offshore Wind Turbine I
41、nstallation does not include the RNA. 5.1.12 Floating Support Structure A Floating Support Structure of an offshore wind turbine is a site dependent offshore structure supported by buoyancy and maintained on location by the Stationkeeping System. The Floating Support Structure consists of the Tower
42、(see 1/5.1.48) and the Hull (see 1/5.1.15) structure. 5.1.13 Foundation System (for Tendons) Structural, mechanical and geotechnical components which are located on and beneath the sea floor and transfer the loads acting on the TLP Tendons into the sea bed. 5.1.14 Gust Brief rise and fall in wind sp
43、eed lasting less than 1 minute. 5.1.15 Hull Combination of connected buoyant structural components such as columns, pontoons and intermediate structural braces; see also Monohull (see 1/5.1.23). Section 1 Introduction ABSGUIDANCE NOTES ON GLOBAL PERFORMANCE ANALYSIS FOR FLOATING OFFSHORE WIND TURBIN
44、E INSTALLATIONS .2014 3 5.1.16 Hub Height Height of the center of the swept area of the wind turbine rotor above the Still Water Level. 5.1.17 Idling Condition of a wind turbine that is rotating slowly and not producing power. 5.1.18 Load External load applied to the structure (direct load) or an im
45、posed deformation or acceleration (indirect load). 5.1.19 Load Effect Effect of a single load or combination of loads on a structural component or system, e.g. internal force, stress, strain, motion etc. 5.1.20 Mean Sea Level or Mean Still Water Level (MSL) Average level of the sea over a period lon
46、g enough to remove variations due to waves, tides and storm surges (see also 4-5/Figure 1 of the FOWTI Guide). 5.1.21 Mean Wind Speed Statistical mean value of the instantaneous wind speed over a specified time interval. 5.1.22 Minimum Breaking Strength (MBS) Certified strength of a chain, wire rope
47、, fiber rope or accessories. 5.1.23 Monohull Floating structure consisting of a single, continuous, buoyant hull, and geometrically similar to an ocean-going ship or barge. 5.1.24 Mooring Components General class of components used in the Stationkeeping System. 5.1.25 Normal Shutdown Wind turbine sh
48、utdown operation in which all stages are under the control of the control system. 5.1.26 Offshore Wind Farm A group of wind turbines installed at an offshore site. An Offshore Wind Farm may also include other installations such as transformer/converter platforms, meteorological measurement facilitie
49、s, electrical cables, accommodation units, etc. 5.1.27 Omni-directional (Wind, Waves or Currents) Acting in all directions. 5.1.28 Parked Condition of a wind turbine that is either in the Standstill or Idling condition, depending on the design of the wind turbine. 5.1.29 Pretension Tension applied to a mooring line or tendon when the Floating Support Structure at its static equilibrium position in mean still water and still air. 5.1.30 Rated Power Quantity of power assigned, generally by a manufacturer, for a specified operating condition of a component, device, or equipment. For wind
