• IEA Wind Task 35
    IEA Wind Task 35

IEA Wind Task 35

Full Size Ground Testing of Wind Turbines and their Components


The proposed task is structured in two project phases. In the first phase the nacelle and rotor will be considered by all participants on product level. At first it is intended to clarify the meaning of the technical wording for WTG and test terms to use an unique terminology in this task. In the following a design analysis of the technical system wind turbine is to be done to classify the WTG on functionality and hardware level. This will help to analyze and benchmark the interaction effects between rotor, tower, nacelle and further subsystems and components. With the analysis of the critical operating conditions it is possible to consider design uncertainties, design limiting and design load cases as well as design assumptions with high sensitivities to operational success of different drive train concepts of wind turbines. Critical load situations of a turbine are to be investigated to develop reasonable load cases for test procedures.

The work packages for phase I are:

Work packages Topics Expected Outcomes
0. Unique definition of the technical wordings Clarify the meaning of WTG and test terms; Product/system/subsystem/nacelle/rotor/powertrain/drivetrain  
1. Design Analysis

Analysis of WTG structure on functionality level

Analysis of WTG structure on hardware level, based on:
  • main components
  • part lists of OEM
Arrange WTG and components in classes
2. Analysis of Interface Which components effects others and how?
Clarify and benchmark the interaction between tower, drivetrain, rotor, control, grid
Identify possibilities for decoupling
3. Analysis of critical operating conditions

Statistical analysis of WTG failures and importance of the failures

Analysis and comparision of component loads of current test rig investigation and in-field loading

Description of critical load conditions

Determinition of loading to be considered on test benches

Building on the activities and results in the first project phase, the second phase work will have two individual project groups focus on the two main systems, rotor blades and nacelle. The topics covered in each task will be similar but adapted to the respective systems and test specifications. Recommendations for test procedures as well as required load application systems on test rigs for different test levels are to be worked out. Open questions are the types, numbers and orientation of load application on test specimen to gain expedient results.

Subtask 1: Blade Test Group

This task addresses advancements in rotor blade testing. Blade reliability has benefitted from relatively mature standards including the IEC 61400-23 and will continue to evolve with nascent manufacturing guidelines including the IEC 61400-5. With increasing blade production and increases in size of turbine blades, new advancements in testing are needed to keep pace with the scale and technology. Work packages focus on improvements in testing that can lead to harmonization of test methods, improved accuracy, and reduce the time needed to validate blade designs. The following table provides an overview of each of the work packages in the blade test group and identifies the specific focus areas.

Work packages Topics Expected Outcomes
0. Evaluation of fatigue test methods
  • Comparison of fatigue test methods
  • Damage equivalence comparisons between single axis and biaxial test methods
Provide consistency between results of different test methods
1. Standard test procedures for subcomponent test methods
  • Evaluation of gaps between coupon and full-scale testing
  • Evaluation of real-time hardware in the loop test methods
  • Evaluate methods for quantifying the effects of manufacturing variances at a subcomponent scale
  • Evaluate the impacts that subcomponent testing may have on reductions to material uncertainty factors
Development of representative structural subcomponents and test procedures for these subcomponents
2. Uncertainty estimation of rotor blade tests
  • Quantify the effects of test setup geometry and load introduction on test results
  • Evaluate the effect of measurement uncertainty in fatigue damage estimation
  • Evaluation of boundary conditions during full-scale testing
Best-practice recommendations for uncertainty estimation in full-scale blade testing
3. Health monitoring and non destructive inspections
  • Evaluation of commonly observed blade defects and methods to quantify performance
  • Evaluation of the sensing capabilities of new health monitoring techniques
Recommended practices for non-destructive inspections and health monitoring systems used during structural testing
4. Standard test procedures for blade repairs and re-certification
  • Evaluate necessary procedures for testing of blade repairs
  • Determine suitable test conditions for life-extension or re-certification of ageing blades
Recommended practices for non-destructive inspections and health monitoring systems used during structural testing

Subtask 2: Nacelle Test Group

In this subtask the definition of the system and subsystems for nacelle testing take the center stage. The subtask focuses on the definition of interfaces between the test bench and the test item as well as the determination of load application for different nacelle test procedures. Depending on the motivation for the test procedures different system levels are to be considered and defined.

The aim of this subtask is to develop and compile a test matrix for basic nacelle test procedures. Following a top down strategy the results from the system nacelle should be used to develop and/or improve test procedures on the subsystem/component level. A description of reasonable boundary settings for subsystem/component tests should be developed.

Work packages Topics Expected Outcomes
0. Definition of different test levels

Minimum requirements for nacelle testing

Requirements for different test procedures:
  • component loads
  • functionality
  • durability
1. Standard test procedures for nacelle Determination of interfaces:
  • mechanical
  • electrical
  • control
  • thermal
Determination of load application:
  • DOF
  • mechanical
  • grid
Development of a test matrix for basic nacelle test procedures
2. Influence of abstraction

Effects of system simplification caused by choice of interfaces and load application

Influence of the substitution of product elements through test bench components (controller, tower)

Demonstration of losses and benefits of system abstraction
3. Standard test procedures for components

Advantages/disadvantages of component testing;
Determination of interaction between components

Determination of interfaces depending on component:
  • mechanical
  • electrical
  • control
  • thermal
Determination of load application depending on components:
  • DOF
  • mechanical
  • grid
Development of a test matrix for basic component test procedures