Enercon joins the 3 MW class

The E-82/3 MW is suited to wind class IA and IIA locations. The E-101 has been specially designed for locations rated up to wind class IEC IIA. The prototype of the 2.3 MW machine has been running since February 2009 at a site in Fiebing in north-western Germany; the remaining prototypes will be installed this year.

ENERCON intends to use these new wind turbines in the 2.3 and 3 MW classes to satisfy the growing demand for wind turbines in this capacity range. Market studies indicate that in Europe alone, there is potential for installing roughly another 80 gigawatts of wind energy power till 2013. “This potential can be exploited to a large degree by machines in the 3 MW class,” says ENERCON Sales Director Stefan Lütkemeyer.

Among the new turbine types, the technology of the E-82/2.3 MW is most closely related to the existing E-82/2.0 MW model. With the same rotor diameter and tower height (between 78 and 138 metres), it can achieve a yield increase of 3 to 6 percent – depending on the wind speed – at the same location. “We‘ve improved the design of the cast iron components in the nacelle and optimised the air cooling system,” explains Arno Hildebrand, Engineering Manager at Wobben Research & Development (WRD).

E-82/3 MW: Top yields for wind class IA

The previously used stator support star of the generator has been replaced with a stator shield that is shaped in such a way as to protect the generator mechanically and to allow further components to be fitted directly to it. In contrast to the E-82/2.3 MW, the E-82/3 MW is also suitable for locations where average wind speeds exceed 8.5 m/s (at hub height). In addition, the generator is somewhat longer than the one in the E-82/2.3 MW. For installations of this wind turbine at wind class IEC IA sites, 85-metre tubular steel towers are used. For wind class IIA sites, the typical ENERCON precast concrete towers (78 to 138 m hub height) are available.

The installation of the E-82/3 MW prototype will begin in January; series manufacturing is scheduled to start towards the end of the year. Power curve calculations for the E-82/3 MW indicate a yield increase of 15 to 20 percent compared to the E-82/2.0 MW – for wind speeds above 8.5 m/s. The higher the wind speed, the larger the difference.

3 MW turbines run with water cooling systems

The E-82/3 MW and E-101/3 MW are fitted with water cooling systems. “This is not really new territory for us,” explains Hildebrand. ENERCON has already used this type of cooling system in more than 150 machines of type E-82 – and achieved an increase in rated power.

“Our experience has been positive. The system works very well.” In contrast to the E-82/2.0 MW, however, the cooling fins are no longer installed on the roof of the nacelle where they would be very noticeable; they are now built into the casing. Water cooling systems have been common in other areas of machine engineering for a long time. They have proven their worth in many diverse areas of application during decades of use. For example, steam locomotives from around the turn of the 20th century had cooling units of a similar shape as those now found in new ENERCON wind power converters.

The use of stainless steels makes sure that the water pipes retain their cooling properties even after 20 years of use. Separate monitoring instruments watch the cooling system constantly. “The operating system detects any changes immediately and reacts accordingly,” explains the WRD design engineer.

Building on tried-and-tested E-82 technology

“In designing the E-101, we‘ve based ourselves mostly on E-82 technology,” says Hildebrand. The E-82 is currently ENERCON‘s mostproduced model. Crucial features such as component size as well as transport and manufacturing dimensions of the new model have been based on those of the E-82. The diameter of the generator has not changed, which means that established standards for transport and manufacturing can remain in place.

The load-bearing components have been reinforced, however, because the rotor area of the E-101 is 1.5 times larger than that of the E-82. Consequently, the machine is subject to stronger forces acting upon it. The E-101 WEC is available with precast concrete towers only, hub heights are 99 or 135 metres. It is designed as a wind class IIA machine, but is also suitable for locations with less intensive wind patterns. At comparable sites, it achieves 1.5 times the yield of a 2 MW machine.

IEC wind classes

The names of the wind classes used in this article correspond to the established standards set by the International Electrotechnical Commission (IEC). The names use Roman numerals from I to IV that refer to average wind speed (I < 10 m/s, II < 8.5 m/s, III < 7.5 m/s, IV < 6 m/s) as well as 50-year extreme values. The appended letters A-C designate turbulence classes. “A” indicates high turbulence (< 18 % at 15 m/s wind speed), “B” medium turbulence, and “C” low turbulence.