Wind Turbine System Design: Volume 1: Nacelles, drivetrains and verification

Contents
About the Editor
Preface
Abbreviations and Terminologies
1 Load calculation and load validation
	1.1 Design loads of wind turbines
		1.1.1 Standard load calculation
			1.1.1.1 Wind conditions
			1.1.1.2 Waves and current conditions
			1.1.1.3 Fatigue and extreme loads
		1.1.2 Use cases and exemplary loads
			1.1.2.1 Rotor blade design
			1.1.2.2 Monopile design
	1.2 Design load validation
		1.2.1 Standard load measurements
			1.2.1.1 Blade bending moment
			1.2.1.2 Tower moments
			1.2.1.3 Main shaft
		1.2.2 Data evaluation process
		1.2.3 Standard load validation
			1.2.3.1 General information
			1.2.3.2 Procedure for the validation of load calculation models
	Acknowledgements
	References
2 Models and simulation
	2.1 Introduction
		2.1.1 Overview of modelling at different levels of fidelity
		2.1.2 Requirements of standards for model fidelity
			2.1.2.1 Requirements for global load simulation
			2.1.2.2 Requirements for gearbox and drivetrain simulation
	2.2 Modelling of environmental conditions
		2.2.1 Modelling of wind conditions
			2.2.1.1 Wind turbulence and power spectral densities
			2.2.1.2 Wind speed distributions in space and time
			2.2.1.3 Extreme wind and gust models
			2.2.1.4 Tower shadow and wakes
		2.2.2 Modelling of sea conditions
			2.2.2.1 Wave models
			2.2.2.2 Current types and models
			2.2.2.3 Modelling of sea ice
			2.2.2.4 Modelling of marine growth
		2.2.3 Modelling of soil conditions
	2.3 Fully coupled wind turbine modelling
		2.3.1 Aeroelasticity and standard tools
		2.3.2 Aerodynamic models
			2.3.2.1 Momentum theory
			2.3.2.2 Blade element momentum theory
			2.3.2.3 Correction models to the blade element momentum theory
			2.3.2.4 More complex aerodynamic models
		2.3.3 Hydrodynamic models
		2.3.4 Modelling of structural components
			2.3.4.1 Blade and tower modelling as beams
			2.3.4.2 Parametrisation of beam models
			2.3.4.3 Equation of motion
		2.3.5 Modelling of other components
	2.4 Detailed modelling of wind turbine drivetrains
		2.4.1 General modelling approaches, methods and tools
			2.4.1.1 Finite element method
			2.4.1.2 Multibody simulation
			2.4.1.3 Bond graph methods
			2.4.1.4 Block models
		2.4.2 Different approaches of modelling a wind turbine drivetrain
			2.4.2.1 Torsional model
			2.4.2.2 Rigid multibody model with six degrees of freedom
			2.4.2.3 Mixed rigid flexible multibody model with six degrees offreedom
			2.4.2.4 Multi-physical high-fidelity model
		2.4.3 Modelling recommendations and best practices
	2.5 Conclusion and summary
	References
3 Pitch system concepts and design
	3.1 Blade bearing
		3.1.1 Preliminary outer bearing design
		3.1.2 Preliminary inner bearing design
		3.1.3 Preliminary design of the bolted connections
		3.1.4 FE blade bearing model
		3.1.5 FE simulation of internal blade bearing loads
		3.1.6 Calculation and dimensioning
		3.1.7 Lubrication system
		3.1.8 Coating
	3.2 Pitch actuator
		3.2.1 Electrical actuator
		3.2.2 Operating conditions
		3.2.3 Calculation and dimensioning
	References
4 Yaw system concepts and designs
	4.1 Fundamentals
		4.1.1 Introduction
		4.1.2 Wind direction and yaw misalignment
		4.1.3 Typical key data
	4.2 Design loads
		4.2.1 Introduction
		4.2.2 Yaw bearing loads
		4.2.3 Yaw drivetrain aerodynamic loads
		4.2.4 Loads acting on the yaw drivetrain
		4.2.5 Modification of yaw drivetrain aerodynamic loads
		4.2.6 Yaw slippage events during non-yawing operation
		4.2.7 Overload events during yawing operation
		4.2.8 Yaw start and stop events
	4.3 System concepts and components
		4.3.1 Differentiating features at system level
		4.3.2 Yaw bearing
		4.3.3 Yaw brake system
		4.3.4 Yaw gearbox
		4.3.5 Yaw motor and yaw motor brake
		4.3.6 Auxiliary systems
		4.3.7 Evaluation criteria
		4.3.8 Common system concepts
	4.4 System dimensioning and design aspects
		4.4.1 Introduction and general requirements
		4.4.2 Step 1: yaw system, holding torque and driving torque
		4.4.3 Step 2a: yaw bearing, yaw brake and yaw drive
		4.4.4 Step 2b: dimensioning of the yaw brake system
		4.4.5 Step 2c: dimensioning of the yaw bearing
		4.4.6 Step 2d: dimensioning of the yaw drive system
		4.4.7 Step 3: auxiliary systems
		4.4.8 Summary
	References
5 Drivetrain concepts and developments
	5.1 Fundamentals
	5.2 Drivetrain concepts
		5.2.1 Drivetrain diversification and classification
		5.2.2 Drivetrain concepts and design principles
			5.2.2.1 “Classic” geared drivetrain concepts (GD)
			5.2.2.2 Geared, medium-speed concepts (referred to asHybrid-Drive)
			5.2.2.3 Gearless concepts (referred to as Direct-Drives)
	5.3 General design rules and procedures
		5.3.1 Safety, protection, reliability and control
		5.3.2 Loads and load cases
			5.3.2.1 Drivetrain with three-point main shaft suspension
			5.3.2.2 Drivetrain with four-point main shaft suspension
		5.3.3 Loads analysis and strength verification
			5.3.3.1 Cycle analysis (fatigue analysis)
			5.3.3.2 Statistical and deterministic extremes (ultimate loads)
			5.3.3.3 Load duration distributions
		5.3.4 Modularization, standardization, and platform concepts
		5.3.5 Scalability of designs and performance indicators
			5.3.5.1 Wind turbine performance indicators
	5.4 Onshore wind turbines and drivetrain developments
		5.4.1 ENERCON
		5.4.2 Nordex
		5.4.3 General Electric wind energy (GE)
		5.4.4 Vestas
		5.4.5 Siemens Gamesa Renewable Energy
	5.5 Offshore wind turbines and drivetrain developments
	5.6 Outlook and potential development trends
	References
6 Gearbox concepts and design
	6.1 Introduction
	6.2 Challenge for load gearboxes in wind turbines
	6.3 Historical drivetrains in wind turbines
		6.3.1 Hybrid systems
		6.3.2 Exceptional developments in the drivetrain
		6.3.3 A Swiss geared wind turbine
		6.3.4 State of the art
	6.4 Basic gear tooth design
		6.4.1 PGT planetary stage in detail
		6.4.2 PGTs have a number of advantages and applications
		6.4.3 Difficulties in using PGTs
		6.4.4 Increasing the power sharing
		6.4.5 The problem of load distribution and its control
		6.4.6 The load-sharing measurement
		6.4.7 Microgeometry
		6.4.8 Absolute, coupling, and relative (rolling) power
	6.5 Bearings
		6.5.1 Bearing failure mechanisms
	6.6 Coupling
	6.7 Mechanical brakes
	6.8 Lubrication system and its design principles
	6.9 Bolted joints
	6.10 Pitch tube
	6.11 Repair work
	6.12 Standards for load gear units in the drivetrain
	6.13 Gearbox design methodology
		6.13.1 Oil quantities and power losses
		6.13.2 Calculation of gearing according to ISO 6336 standard (Part 1-6)
	6.14 Future prospects
	6.15 Conclusion
	References
7 Hydraulic systems and lubrication systems
	7.1 Hydraulic systems
		7.1.1 Main Components
		7.1.2 Hydraulic auxiliaries
		7.1.3 Manifold / control block
		7.1.4 Centralized and decentralized systems
		7.1.5 How to engineer a hydraulic power pack
	7.2 Hydraulic pitch systems
		7.2.1 History
		7.2.2 Pitch control
		7.2.3 Hydraulic pitch adjustment systems
			7.2.3.1 Systems with 4/3-way proportional valve
			7.2.3.2 Systems with 2/2-way proportional seated valve
			7.2.3.3 Differential circuity
		7.2.4 How to engineer a hydraulic pitch system
			7.2.4.1 Cylinders
			7.2.4.2 Pump/motor assembly and tank size
			7.2.4.3 Pitch accumulators
			7.2.4.4 Pitch valve
		7.2.5 Outlook
	7.3 Automatic lubrication system for bearings
		7.3.1 Fundamentals
		7.3.2 Components of an automatic lubrication system
			7.3.2.1 Lubrication pump
			7.3.2.2 Progressive distributor
			7.3.2.3 Lubrication tubing
			7.3.2.4 Lubrication pinion
			7.3.2.5 Collection of old grease
		7.3.3 Simplified exemplary design of an automatic lubrication system
			7.3.3.1 Design of lubrication pump tank volume
			7.3.3.2 Tank volume – yaw raceway lubrication
			7.3.3.3 Tank volume – yaw teeth lubrication
			7.3.3.4 Progressive distributor layout – yaw raceway lubrication
			7.3.3.5 Progressive distributor layout – yaw teeth lubrication
			7.3.3.6 Lubrication pinion layout - yaw teeth lubrication
			7.3.3.7 Collecting old grease
		7.3.4 Schematic overview and final clarifications
			7.3.4.1 Final clarifications
				7.3.4.1.1 Control software
				7.3.4.1.2 Electrical connection
				7.3.4.1.3 Mechanical connection
	References
8 Cooling systems concepts and designs
	8.1 Introduction
	8.2 Gearbox
		8.2.1 Filtration
	8.3 Generator
	8.4 Main converter
	8.5 Main transformer
	8.6 Essential questions for cooling system design
	8.7 Example - cooling design for IWT-7.5-164 variant
	8.8 Experiences
	References
9 Validation, verification, and full-scale testing
	9.1 Introduction
	9.2 Validation and verification strategy
	9.3 Purpose of testing
	9.4 Product development using the V-Model
	9.5 Full-system testing
		9.5.1 Certification measurements
		9.5.2 Measurements on the yaw system
	9.6 Integration testing
		9.6.1 System test benches
		9.6.2 Test requirements
		9.6.3 Projecting a nacelle test campaign
			9.6.3.1 Preliminary engineering
			9.6.3.2 Assembly, commissioning, and disassembly
			9.6.3.3 Test conduction
	9.7 Sub-system testing
		9.7.1 Gearbox
		9.7.2 Brake system
	9.8 Component testing
		9.8.1 Main shaft
		9.8.2 Pitch bearing
		9.8.3 Rotor blade
	9.9 Material testing
		9.9.1 Leading edge protection
		9.9.2 Polymer and composite testing
	9.10 Outlook
	References
10 Main shaft suspension system
	10.1 Introduction and bearing arrangement selection
		10.1.1 Cylindrical roller bearings
		10.1.2 Spherical roller bearings
		10.1.3 Toroidal roller bearings
		10.1.4 Tapered roller bearings
		10.1.5 Moment bearings
		10.1.6 Bearing type and bearing arrangement selection
		10.1.7 Bearing type selection in relation to the drivetrain concept
		10.1.8 Influence of turbine size on rotor bearing size and type
	10.2 General design and bearing calculation process
		10.2.1 Drivetrain for calculation example
		10.2.2 Calculations according to applicable standards and guidelines
		10.2.3 Rated life calculation
		10.2.4 Contact stress
		10.2.5 Static safety
		10.2.6 Loads for rotor bearing calculation
		10.2.7 Extreme loads for rotor bearing calculation
		10.2.8 Fatigue load cases for bearing calculation
		10.2.9 Bearing calculation models and software
		10.2.10 Rigid calculation model
		10.2.11 Calculation with the stiffness matrix
		10.2.12 Calculation with non-linear stiffness (FE calculation)
	10.3 Example for rotor bearing calculation
		10.3.1 Influence of calculation model and boundary conditions
		10.3.2 Definition and influence of bearing system preload
	10.4 Reliability, failures and root causes
	10.5 Development trends
	References
Index