Nacelle Testing

Improved time to market

© Photo IDOM
© Photo Meike Bierther, PTJ
© Photo Martina Buchholz

In 2015 Germany´s first test facility for complete nacelles of wind turbines has started operation. The Dynamic Nacelle Testing Laboratory (DyNaLab) offers wind turbine manufacturers reliable tests under realistic conditions in the laboratory, contribute to the evaluation and optimization of established and future turbine concepts.

With the grid and the hardware-in-the-loop wind load simulations, various loading scenarios can be simulated in a reproducible manner and the performance of a turbine in the event of emergency stops, multi dips in the grid following storms and grid short circuits due to faulty pitch regulation can be tested experimentally

The aim of tests on the test bench is to considerably shorten the certification process. With the grid and the hardware-in-the-loop wind load simulations, various loading scenarios can be simulated in a reproducible manner and the performance of a turbine in the event of emergency stops, multi dips in the grid following storms and grid short circuits due to faulty pitch regulation can be tested experimentally.

As such, operational management and control can be optimised and models validated. This makes an important contribution to increasing the reliability and availability of turbines and, at the same time, also reduces maintenance and repair costs.

TECHNICAL DATA
Investment: approx. 35 Mio. Euro

• Force application: dynamic application of 20 MNm bending moment, ca. 2 MN thrust forces
• Nominal torque: 8,6 MNm
• Overload torque: 13 MNm
• Drive Performance: 10 (15) MW
• Artificial network with 40 MVA installed inverter power
• Measurements: more than 600 synchronous, high resolution measuring channels

Film: Constructing a nacelle test stand - from sketch to operation. IDOM/Old Port Films

“My associates and I have joined forces to pave the way for this innovative technology. The simple set-up of the generator, its easy manufacturing and impressive electrical properties mark a quantum leap for the onshore and offshore wind industry.“
© Photo Hans-Henning Jacobs, Associate Jacobs Powertec

“My associates and I have joined forces to pave the way for this innovative technology. The simple set-up of the generator, its easy manufacturing and impressive electrical properties mark a quantum leap for the onshore and offshore wind industry.“

“As a quality-oriented supplier of wind turbine components, Schaeffler is convinced that laboratory tests and validation can contribute significantly to increased reliability. Parallel to these activities, Schaeffler is focused on the development of comprehensive simulation models that help to define the limits of the application. Fraunhofer IWES, with their new test rigs, is an ideal partner for this.“
© Photo Andreas Mangold, Schaeffler Technology

“As a quality-oriented supplier of wind turbine components, Schaeffler is convinced that laboratory tests and validation can contribute significantly to increased reliability. Parallel to these activities, Schaeffler is focused on the development of comprehensive simulation models that help to define the limits of the application. Fraunhofer IWES, with their new test rigs, is an ideal partner for this.“

Prototype validation and certification in the laboratory

Wind torque is reproduced using two excited synchronous motors which are arranged in tandem and have a drive power of 5 MW each. This means that 10 MW are provided for the test operations. This in turn, means a nominal torque application of 8,600 kNm on the specimen. The complete test stand drive is tilted to an angle of 5°. This corresponds with the actual positioning of a wind energy turbine in the field and thus represents the realistic load situation. The engine torque is applied to the specimen via a link coupling.

The reproduction of mechanical wind loads such as driving torques or bending moments are created by hydraulic force application. The load-bearing structure is connected with a flange adaptor via a moment bearing. By this means, torque and forces can be transferred from the non-rotating load-frame onto the rotating shaft. Using this unique configuration bending moments of ca. 20 MNm and thrust in the range of 2 MN can be achieved. Furthermore, radial loads can also be reproduced dynamically. The force transmission furthers the nacelle test stand by five additional degrees of freedom.

With the aid of a drive motor and the hydraulic force application the interactions between nacelle and rotor blades can be simulated realistically in the DyNaLab. Here, wind load simulations can comprise of simulations from varying static and dynamic operating conditions as also from real-time simulation load data. In order to test wind energy turbines as comprehensively as possible, pitch systems as well as yaw systems can be integrated into turbine testing. For this purpose, individual system control values using actuators are implemented in realtime simulation.

Further focus lies in electrical network simulation and the resulting possibility of nacelle electrical nacelle certification on the test stand. In order to achieve this, the world’s most comprehensive grid simulation is installed in the DyNaLab. Here, static tests can be carried out in order, for example, to examine effective and idle power in various network situations or the thermal behavior of electronic components. Furthermore, transient grid events can be simulated which can impact the complete nacelle system. For this purpose, dynamic Low-Voltage-Ride-Through (LVRT) and High-Voltage-Ride-Through (HVRT) events corresponding to the respective grid codes are simulated on the test stand. An inverter capacity equivalent to 40 MVA is available for these tests. Harmonic current behaviour and nacelle system perturbation can also be investigated in DyNaLab.

Due to the missing rotor and tower, the nacelle has different system characteristics on the test stand than those in the field. In order to simulate real conditions in the laboratory occurring loads and the interactions between nacelle and rotor are calculated and applied. The necessary wind turbine real-time models and the appropriate control algorithms are developed and the necessary hardware components specified in order that the test stand including specimen can operate in the Hardware in the Loop (HiL).

Publications

2016

Converter lifetime assessment for doubly-fed induction generators considering derating control strategies at low rotor frequencies
Morisse, M.; Bartschat, A.; Wenske, J.; Mertens, A.
(Conference Presentation)

6th International Conference "The Science of Making Torque from Wind", TORQUE 2016 - TU München & European Academy of Wind Energy EAWE
5.-7. Okt. 2016, München
DOI: 10.1088/1742-6596/753/11/112003 (full version)
http://publica.fraunhofer.de/dokumente/N-417662.html


Analysis of dynamic interactions between different drivetrain components with a detailed wind turbine model
Morisse, M.; Bartschat, A.; Mertens, A.; Wenske, J.
(Conference Presentation)

6th International Conference "The Science of Making Torque from Wind", TORQUE 2016 - TU München & European Academy of Wind Energy EAWE
5.-7. Okt. 2016, München
Bristol: IOP Publishing, 2016 (Journal of physics. Conference series 753)
Art. 082022, 12 S.
DOI: 10.1088/1742-6596/753/8/082022 (full version)
http://publica.fraunhofer.de/dokumente/N-417668.html


Extending the scope of gearbox oil condition monitoring for wind turbines: Identified challenges and recommendations
Coronado, D., Wenske, J.
(Poster)

Wind Europe Summit 2016
27.-29. Sept. 2016, Hamburg
urn:nbn:de:0011-n-4176892 (full version)
http://publica.fraunhofer.de/documents/N-417689.html

 

Advanced grid simulator topology for testing of renewable energy supply units especially wind energy converters (WECs) under laboratory conditions
Mehler, Christian; Jersch, Torben; Koralewicz, Przemyslaw; Tegtmeier, Bernd
(Conference Presentation)

18th European Conference on Power Electronics and Applications
5-9 Sept. 2016, Karlsruhe
DOI: 10.1109/EPE.2016.7695474 (full version)
http://publica.fraunhofer.de/dokumente/N-423847.html

 

First results of a testing campaign to validate oil sensors for wind turbine gearboxes
Coronado, Diego
(Presentation)

VGB Conference - Maintenance of Wind Power Plants
2.-3. März 2016, Hamburg
zu Fraunhofer Publica

 

Wind turbine loads reduction using feedforward feedback collective pitch control based on the estimated effective wind speed
Meng, Fanzhong; Wenske, Jan; Gambier, Adrian
(Conference Presentation)

American Control Conference (ACC)
July 6-8, 2016, Boston, MA
DOI: 10.1109/ACC.2016.7525259 (full version)
http://publica.fraunhofer.de/dokumente/N-406636.html


Sensorless control for active damping of torsional vibrations in wind turbine drivetrains with doubly-fed induction generator
Wenske, J., Beckert, U.
(Presentation)

International Conference on Renewable Energy and Power Quality (ICREPQ)
May 4-6, 2016, Madrid, Spain
urn:nbn:de:0011-n-4066376 (full version)
http://publica.fraunhofer.de/documents/N-406637.html


Control design for mechanical hardware-in-the-loop operation of dynamometers for testing full-scale drive trains
Fischer, Boris; Mehler, Christian; Zuga, Adam; Shan, Martin
(magazine article)

Wind energy (2016), Online First, S.13
zu Fraunhofer Publica


Kraftübertragungselement für einen Prüfstand zum Testen eines Lagers sowie Prüfstand
Bartschat, Arne
(Patent)
zu Fraunhofer Publica