Close up - Prokon develops 3MW direct drive turbine

GERMANY: Wind developer Prokon has taken the decision to take control of its turbine supply and develop its own 3MW turbine. Windpower Monthly technology correspondent Eize de Vries spoke to Prokon about the machine.

Prokon's 3MW turbine
Prokon's 3MW turbine

This summer German project developer Prokon will install two prototypes of its new in-house developed 3MW P3000 turbine in the federal states Mecklenburg-Vorpommern and Schleswig-Holstein. Serial production will be ramped up from 2014, for projects in Germany, Poland and Finland.

Prokon's decision to develop its own turbine stemmed from its wish to gain reliable, low-maintenance wind technology and greater independence from market fluctuations when planning new wind farms. Albrecht Schöttle, head of Prokon's turbine development and production, cited his company's slogan 'All from one hand' signalling a strong drive to be as independent as possible.

The first 3MW P3000 turbine for IEC class III sites features a 116-metre rotor diameter and a direct drive permanent magnet direct drive generator (PMG). The head mass (nacelle + rotor) is about 200 tonnes. A sister model for IEC class II sites, with a rotor diameter of around 110 metres, is in development. Schöttle said: "The IEC class III turbine is available with a 92-metre hub height tubular steel tower or two different hybrid concrete-steel towers of 122-metre (in development) and 142-metre hub heights."

Prokon was established in 1995 and is active with wind, biogenic fuels and biomass projects. It operates 296 wind turbines spread over 49 wind farms with a cumulative installed capacity of 489MW. The company boasts 17 years of operating experience with five different third-party turbine makes and models.

Schöttle explained that the experience derived from this track record was fed into the development of the P3000 in order to meet specific company requirements. He added that Prokon does not aim to compete with established suppliers but solely to produce turbines for its own projects in Germany, Poland and Finland.

Schöttle: "While we are not trying to beat other suppliers, our turbines still have to be competitive and we put in huge efforts to build a technologically state-of-the-art, reliable and cost-effective wind turbine, and an efficient supply chain. Prokon cooperates with German engineering consultancy Tembra, which developed the P3000 under our guidance. We further cooperated with German firm CimTT in developing a new production plant, built and completed in Itzehoe, where our headquarters is based. Assembly of the first pre-series prototypes is taking place.

The final choice for a direct drive PMG system was based on a comprehensive evaluation of 15 years in-house operating experience with conventional gear-driven turbines. Schöttle pointed to high gearbox-related operations and maintenance, adding that before its final decision on turbine design configuration, Prokon commissioned engineering consultancy PE Concepts to conduct a second independent study: "This feasibility study was specifically aimed at getting a clear and comprehensive picture on wider turbine design choices. It covered essential questions about turbine configuration, rated power and rotor diameter, hub heights, geared drive versus direct drive, PMG or classic synchronous direct drive generator."

An essential element of the P3000 system is a newly developed 690V outer-rotor air-cooled generator, featuring a six-metre outer diameter. It comes with a fully integrated bearing assembly, incorporating two taper-roller bearings. Two different specialists, The Switch of Finland and Germany's Siemens Large Drives, each supply Prokon with these complete, fully pre-assembled generator-bearing units and the power-electronic converters.

With the hybrid towers a medium-voltage transformer is located in the tower base, while the shorter tubular steel tower comes with an external transformer housing."

The 116-metre model will be fitted with 56.8-metre glass fibre-reinforced epoxy blades supplied by German blade manufacturer Euros. This state-of-the-art product does not contain carbon fibres, according Schöttle.

Prokon expects to produce 30-50 P3000 turbines in 2014 and then 100 units annually therafter. The maximum annual capacity of the Itzehoe plant is 200 turbines. Finally, the company recently placed orders for another 100 generators and power-electronic converter sets with The Switch, and also signed a framework contract with Siemens Large Drives for the supply of generators. Both contracts underline the seriousness of the P3000 turbine development project and the company's determination to fulfil its ambitious plans quickly and independently.

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