Reliability and predictability are key words for the Vestas test program. With the new V164-7.0 MW, Vestas has designed a turbine specifically made for offshore power generation. The mega-turbine is being prepared for the second level of the test program – the testing of sub-systems.
By Tea Tramontana
“We want to be the best on reliability,” short and to the point says Carl Erik Skjølstrup, Vice President, Mechanical Systems, Vestas Technology R&D. For him, thorough testing is one of the means to achieving this goal.
Reliability of a turbine is about customers being able to rely on an optimal production over 25 – 30 years. Predictability is about customers knowing which components will last for a planned time span. This allows planned servicing and maintenance throughout the lifetime of a turbine.
“Basically we want all major components to last 25 – 30 years because it is very expensive to replace them, especially offshore. But with some components it is too costly to give them this kind of lifetime. In that case we want planned replacement of e.g. the cooling pump. It is all about business case certainty,” says Carl Erik Skjølstrup.
A wake-up call
Three or four years ago, Vestas had huge problems with the gearboxes of the V90-3MW turbine. These problems resulted in a loss of offshore market share.
“Without doubt, it was a wake-up call", says Carl Erik Skjølstrup and repeats the question properly asked at the time: how to do something about it? This resulted in the start of a thorough test program at Vestas and the breakthrough of actually making simulation, testing and verification an integral part of the development process. The test of components, subsystems and the full turbine with the installation of prototypes are in short the ingredients, mixed in a combination of testing functionality, performance and reliability.
“We constantly optimize the simulation and get closer to “real life” because we have input from 16,000 turbines producing energy around the world in all kinds of different conditions. This means that we have a huge base of knowledge about loads, how the turbine is influenced and how the turbine and its subsystems and components act and react when working together.”
Gears are here to stay
Following the challenges with the gearboxes, Vestas managed to reproduce the problems occurring offshore in a test environment, and through testing and simulations they developed solutions which lead Carl Erik Skjølstrup to say:
“Through reliability and verification testing, we can demonstrate that the gear will fulfil its 20 years of life in service.
“We know the geared solution, we know why we had errors in the gearboxes, and to us it is more realistic to stay with this solution than to jump into something unproven that you might find attractive just because you have not yet had any bad experiences with it. Again, it is about business case certainty.”
Carl Erik Skjølstrup confirms that this is the picture of an industry that “grew up”. And so did the customers. From farmers and small private cooperatives buying one turbine, they are now huge energy companies buying power plants. And they are professional – and want to know the product down to the level of each component and the results of the component tests.
Test facility for testing of gear and nacelle. Photo: Vestas Wind Systems
Tests shorten the time to market
Testing is also about shortening the time from when the turbine exists “on paper” to the day that it is actually out there producing energy.
That is part of the reason that Vestas Offshore is among the initiators of LORC and working closely together with LORC engineers to investigate the Lindoe Nacelle Testing. With regard to the V164-7.0 MW offshore turbine, Carl Erik Skjølstrup is in no doubt:
“We participate in LORC because the importance of the offshore market is increasing, especially in Northern Europe. At LORC there is an opportunity to increase the level of testing to the full dynamic system of a turbine with accelerated loads and actual grid performance – not only the drive train and generator, but also the pitch and yaw systems,” says Carl Erik Skjølstrup, and adds:
“It could shorten the amount of time we use at present on testing prototype turbines”.