Vestas Wind Systems’ test program has several phases, ranging from the critical component level through to the testing of main components/sub-systems, systems, the whole turbine and finally the whole offshore power plant generating renewable power.
Around 2,000 people are employed in Vestas Technology R&D responsible for development of wind turbines and power plant solutions. A centralized function is managing all testing with test facilities located in Aarhus and Ringkøbing , Denmark, the Isle of Wight, UK, Boston, USA and in Chennai, India.
Vestas is currently preparing tests of components and sub-systems for the new V164-7.0 MW offshore turbine. Like every other Vestas turbine the V164-7.0 MW is developed and run through computerized numeric models at the component, system, and turbine level in order to simulate the real life situations that a turbine will experience. The computer-based simulation reflects as widely as possible the full lifecycle of the turbine and this computerized development of turbines is conducted and finalized before the turbine is built and tested “for real”.
3D modelling. Photo: Vestas Wind Systems
Testing of critical components
A turbine consists of several thousand functional components – without counting all the bolts and nuts, etc. Testing of critical components consists of various tests mainly aimed at validating computer models, verifying functionality and performance or exposing the components to increased loads in order to get to know the limits of the design with respect to wear or fatigue.
For example, bearings are tested in a bearing test rig. Based on online input from turbines producing energy in real life, Vestas tests 20 to 25 years of use of a pitch component in 3 - 6 months by accelerated testing – the so-called HALT (Highly Accelerated Lifetime Testing). Another example is the stress testing of all electronic components, exposing them to high levels of vibration, temperature, humidity, etc.
A glance into the nacelle of a turbine reveals several critical components, but also main components or sub-systems such as the gearbox, which converts low-speed rotation from the input shaft of the rotor to high-speed rotation driving the generator, the main bearing arrangement and the generator itself. It can take two years to simulate and test 20 - 25 years of use of the main bearing because there are limits to the level of acceleration that the main bearing can be exposed to.
Vestas tests the main components and subsystems such as gears, generators, converters in the test centre in Aarhus, while critical components such as pitch cylinders and yaw gears as a principle are tested in Chennai.
Vestas pitch system testing. Photo: Vestas Wind Systems
Testing of sub-systems and systems
Taking a look into the Vestas way of testing one of the systems – the drive train or power train - the testing is first of all a question of simulating the loads and different operating conditions that the turbine will experience in actual service. For example, the variable torque from the rotor which the gear will have to transfer and which will result in deflections in the shaft: i.e. vibrations from the blades, emergency stops, cold starts, etc. The loads that the drive train will experience during the lifetime of a turbine are described in a very advanced test protocol, which is programmed into the drive train test stand for execution of the accelerated tests.
The testing of the sub-systems in the new V164-7.0 MW turbine will follow the same program – with testing of critical components, main components and systems. In other words, the toolbox is the same. But because of the size of the 7MW turbine, Vestas will put emphasis on the testing of system integration.
The new turbine for offshore from Vestas is the V164-7.0 MW. Photo: Vestas Wind Systems
Validation of the full turbine
When Vestas installs the prototypes of the V164-7.0 MW the lab-testing is actually complete. Prototype installation in the field is merely a verification of the turbine. The prototypes of the V164-7.0 MW are to be installed in 2013 and the serial production of the new offshore turbine will begin in 2015.