Based in the north of Germany, Elegant Energy GmbH & Co KG is a small, but enormously innovative and capable company motivated by the belief that every human being has the right to clean and limitless energy. In support of this belief the company has developed Marlene, a new vertical axis wind turbine that is versatile, efficient, compact and cost effective. Central to Marlene’s design and operation is a high performance NX-series grid converter from Danfoss Drives.
As is the case with all wind turbines, the output voltage and frequency from Marlene’s generator varies with wind speed. To convert this output to the stable voltage and frequency needed to supply most types of load and to feed into the power grid, an inverter system, often known as a grid converter, is required. To provide a grid converter suitable for Marlene, Elegant Energy approached Danfoss Drives.
By opting for a standard product rather than a specially developed custom grid converter, Elegant Energy eliminated development costs. Even more importantly, it gained the benefit of having a converter with proven performance and reliability which had already been type tested and shown to be fully compliant with relevant standards and regulatory requirements.
For use in Marlene, which has an 8 kW generator, Elegant Energy chose grid converters from the Danfoss Drives NX family. These are available in a wide range of sizes with power ratings up to several megawatts, so scalability of the Marlene design is assured, should there be a demand for uprated versions to be used in areas with higher than average prevailing wind speeds. A further important benefit is that, as a result of Danfoss Drives’ in-depth understanding of and forward-thinking approach to renewable energy applications, the NX converters have standard pre-programmed functions that Elegant Energy found extremely useful.
“The prohibited frequency function has greatly simplified the design of Marlene,” said Kim van Wagtendonk, co-owner of Elegant Energy. “It meant we could eliminate resonance problems without incurring any additional costs, and it was exceptionally easy to use. All we had to do was to specify the upper and lower limits of the rotor speed band where resonance could occur – just a few minutes work to solve a potentially difficult and expensive problem!”
Currently Elegant Energy is using its experience from the first Marlene to help prepare series production. First orders have been placed and international interest is even greater than expected.
“Danfoss Drives has without doubt played a key role in the success of the Marlene project,” said Kim van Wagtendonk, “and the company has been a delightful partner to work with. Although we are a comparatively small operation, Danfoss Drives has always supported us unstintingly and enthusiastically, and whenever we have needed help or advice, the Danfoss team has provided a fast, accurate and helpful response. I would recommend Danfoss Drives to anyone working in the renewable energy field – it really is a ‘can-do’ company with great products and great people.”
