Denmark is setting a new standard for wind turbine testing technology. The Lindu Marine Renewable Energy Centre (LORC) in Denmark is able to test wind turbine nacelles for all wind loads and torsional moments they may experience during their more than 25-year lifespan. They utilize Beckhoff's automation technology for test bench control.
As wind turbines become larger and more expensive, the need to minimize the risk of damage throughout their lifespan is also increasing. This necessitates load testing on actual wind turbines before mass production of a new generation. The mission of LORC, the world's largest wind turbine test rig (up to 10 MW), launched in Monkbo, Denmark in December 2017, is to provide the most rigorous High Accelerated Life Testing (HALT). Large-scale wind simulators use mechanical, hydraulic, and electrical functions to generate the pressures and stresses a wind turbine would withstand over its entire 25-year lifespan over six months. This type of testing helps identify design and structural flaws, allowing for necessary modifications before mass production of wind turbines.
Despite the test bench weighing 4,000 tons, the TwinCAT3 software was still able to quickly achieve control and easily integrate advanced simulation models.
Test bench with real experimental environment conditions
Danish engineering company R&DTestSystems was the turnkey supplier for this facility, responsible for implementing the entire project: from designing and developing mechanical components to programming and commissioning. The complex development and implementation process took many years to complete. To ensure a smooth commissioning process and guarantee the test bench's stable and reliable performance, all functions had to be thoroughly simulated and tested. The simulation models and test results were used for further software development and operator training.
At the testing center, realistic fatigue tests are conducted on the mechanical components of wind turbines based on wind and weather data from wind farms around the world. Michael Nielsen, General Manager of Beckhoff Denmark, explains, “The ability to simulate real-world environmental conditions is becoming increasingly important for wind power and other industries employing heavy-duty solutions. In the long run, if manufacturers can understand how wind turbines will behave in real-world applications, it can help them save significant resources.” Beckhoff provides the foundation for the standardization and monitoring of all test scenarios through TwinCAT3 software, powerful industrial PCs, and various EtherCAT I/O terminal modules. These components are installed by Danish control cabinet supplier Tricon Electric A/S.
Every newly developed wind turbine must be tested as a complete system. Given the enormous size of modern wind turbines, testing them is extremely difficult. Therefore, manufacturers test the nacelles themselves, simulating the rotor, circuitry, and other environmental conditions as realistically as possible on test benches. To map all force and torque factors affecting the main turbine shaft and nacelle, the new HALT test bench required a unique design. Constructing such a facility, 31 meters long, 8 meters wide, and 13 meters high, required 310 tons of steel and 107 concrete pillars (which had to be buried 16 meters underground). Weighing 4,000 tons, the test bench employs a hydraulic bending system capable of applying bending moments up to 25 MNm to the wind turbine under test. These forces are generated by hydraulic cylinders, and a drive system with a torque of 14.5 MNm generates the wind force applied to the rotor.
When wind shear, strong winds, or wind disturbances impact the rotor, additional bending moments and thrust are generated. The test bench regenerates these forces through hydraulic cylinders in a six-degree-of-freedom structure. However, since there is no wind turbine tower or rotor, the system must simulate these real-world conditions as accurately as possible. Therefore, the simulation model must monitor the interaction between the nacelle and the rotor in real time and send corresponding signals to the hydraulic cylinders. The system can simulate various operating conditions, such as the nacelle's behavior during storms or after grid failures and emergency shutdowns.
Simulation in the millisecond range
During test runs, sensors must be able to acquire, process, and transmit large amounts of data in the shortest possible time. Therefore, all test bench components and test objects must be modeled in MATLAB®/Simulink® before commissioning. Allan Mogensen, Software Manager at R&DTestSystems, said, “Because the software must be able to respond to various test scenarios as quickly as possible, we wanted to minimize the loop time. Through comparison, we found that Beckhoff’s TwinCAT3 automation software allowed us to achieve a loop time of 1 millisecond, so we chose the Beckhoff system.”
The MATLAB®/Simulink® software interface in TwinCAT3 is another advantage. Allan Mogensen added, “To ensure excellent performance and strong operability, we simulated all the functions on the computer by creating MATLAB®/Simulink® models of all the physical components of the test platform and the actual test objects that LORC customers wanted. The MATLAB® model simulation can be used as a benchmark for later real-world testing of the real physical mechanical system without posing a threat to the mechanical system. This allowed us to achieve our goals faster than originally planned.”
Allan Mogensen summarized, “This test rig is a ‘lighthouse project’ for Denmark and the Danish wind power industry. We delivered a HALT facility that enables faster and more efficient testing of wind turbines. Sufficient computing power was crucial to the implementation of this project. Beckhoff’s hardware and software ideally meet these requirements.” Morten Hauge, a sales engineer at Tricon Electric, agreed with Allan: “Providing such an advanced solution for such a large project is an interesting and challenging task. Beckhoff’s hardware possesses the level of intelligence required to perform such demanding tasks.”
Beckhoff's hardware components are housed in six control cabinets provided by Tricon Electric and communicate with each other via a powerful EtherCAT network.
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