The Challenge: Ensuring the long-term quality and reliability of various types of wind turbine drive train components.
The Solution: Adopting the NI LabVIEW software and CompactRIO hardware platform to create a generic, flexible, high-channel-count measurement system for design verification and reliability tests to be completed in a test center and in the field.
Vestas Uses Test to Beat Competitors
Vestas is a global leader and manufacturer of onshore and offshore wind turbines. The company’s objective is to provide customers with the most reliable, durable wind turbines at the lowest cost per kilowatt hour produced. To achieve this objective, Vestas engineers perform more tests on the wind turbine than any other company in the industry.
A crucial system in a wind turbine is the drive train. The drive train consists of various components including bearings, a main shaft, a gearbox, and a generator. We use modeling and simulation to design the drive trains, and then a thorough design verification process to validate the models offline with real-world data from our test rigs. In addition, we perform durability tests on the various drive train components, both in our controlled test center environment and in the field, to ensure a life span of at least 20 years. Performing these durability tests also helps us create a maintenance schedule for these components.
Test System Requirements
The gearbox test rig needed to be a reliable measurement system with the flexibility to connect to any sensor or communication protocol that the gearbox designers required. We also needed to dynamically add test rig and turbine control data. We needed a system that could sample hundreds of I/O channels at a high sample rate in physically separated areas. For the best possible model verification, we also needed the measurement system to tightly synchronize all I/O channels sample by sample in order to detect how events happening in the rotating part of the gearbox influence the gearbox as a whole. Additionally, we needed to log all the measurement data to a host computer for online signal processing and offline analysis.
An off-the-shelf system that met our requirements was not available on the market. Therefore, we needed a software-defined platform that we could use to both customize the initial test system and to update and customize it for new tests. We chose LabVIEW and CompactRIO as the measurement platform for drive train testing because it offers the flexibility, ruggedness, tight synchronization, and mixed-sensor connectivity that we needed. CompactRIO also has the environmental specifications and small size necessary to deploy the measurement system in the field where temperatures range from -20 to 50 °C and humidity and salt can be a challenge. Additionally, LabVIEW has proven to be a very good development environment for large, complex applications such as our measurement system.
Because of the expected development time and the complexity of the application, we used CIM Industrial Systems A/S, a National Instruments Alliance Partner in Denmark, to design the architecture and provide the solution. With more Certified LabVIEW Developers and Architects than any other NI Alliance Partner in Europe, they were an ideal partner for this project. CIM used its structured development process to provide very detailed design and software documentation, which will make it easy to implement, maintain, and modify the measurement system for many years to come.
Figure 1: The big challenge is the sample-by-sample data synchronization between different sensor types in the rotating hub and the nacelle.
Measurement System Design
CIM designed a measurement system consisting of several CompactRIO systems capable of making hundreds of temperature, vibration, movement, and strain measurements in several places in the gearbox. All CompactRIO devices behind the slip ring in the gearbox are connected to a host PC through a 100 Mbit/s Ethernet connection, and the CompactRIO node before the slip ring is connected through Wi-Fi. We use a GPS clock signal (PPS) to synchronize all I/O channels, each making exactly 2,000 measurements per second with an accuracy of 2 µs, and the IEEE 1588 precision time protocol to synchronize the data packets.
The LabVIEW application is flexible and reliable and is extremely stable thanks to the advanced software architecture, to which NI engineering also contributed. The easy-to-use configuration menus in LabVIEW make it simple to add CompactRIO modules for new measurements or to add new sensors to existing modules.
Figure 2: A simplified design overview of the complex software design on the host computer.
Because of the scalability and tight I/O channel synchronization in our measurement system, we can verify the models and simulation results of the drive train using very detailed data. In addition, because of the reliability and sturdiness of the test system, we can run long durability tests on the gearbox and be confident that all data is securely logged and for a very long time. We also implemented connectivity to the turbine controller for further optimization.
This test system ensures the structural reliability of the gearbox, and thus contributes to longer uptimes and lower turbine costs. In fact, the latest Vestas wind turbine, the V112-3.0 MW, has the lowest cost per kilowatt hour on the market.
In the future, we’d like to capture higher frequency vibrations by increasing the sampling rate of the measurement system and adding turbine event-triggered data collection. We would also like to expand the measurement system further by including other parts of the drive train, and even the entire wind turbine. There are plans to implement this system at all of our test centers around the world.
Rasmus Vistisen, Vestas Wind Systems A/S
Hedeager 42 8200 Århus N