E-126 turns into 7.5 MW wind turbine

The modified E-126 is now suitable not only for IEC wind power class I sites with turbulence class C, but also for wind classes IA and IB. To achieve this, some minor modifications were made. For example, the machine design was adapted to load assumptions for locations with stronger turbulence.

In addition, the generator cooling system was optimised. The ventilation fans of ENERCON wind energy converters are built into the nacelle casing. The air intake has been modified in such a way that the cooling capacity can be exploited more efficiently.

“We have tried and proven that we can operate the E-126 safely and with the required reserves even at 7.5 MW rated power,” explains Arno Hildebrand, Head of Construction Department at Wobben Research & Development in Aurich. A monitoring system supports the control system of the wind turbine. “Depending on the location, the WEC control system assesses the loads that occur and mitigates any extremes, for example by pitching the rotor blades or turning the nacelle,” says Hildebrand.

In late November, ENERCON installation teams for the first time used the new, ENERCON-owned Terex Demag CC 9800 large-scale crane to hoist an E-126 hub near Emden, Germany. The crane fully proved its worth and accomplished some truly heavy-duty work. The hub with the pre-assembled inner blade segments weighs in at 340 tons. At the working radius required to hoist the hub, the Terex-Demag has a maximum lifting capacity of 360 t.

Rigging the hub took five hours alone; lifting it off the centre frame another hour. A smaller crane took care of guiding the hub, making sure the downward-pointing rotor blade did not touch the ground when the hub was tilted. The hoisting itself was completed in 20 minutes. The installation team then spent the remainder of their work day inside the nacelle, bolting rotor and machine house. Project manager Sonja Kehmeier is proud that the entire installation process could be completed in just 2.5 months, from tower construction to the mounting of the blades.

“Because the end of the year was close, we were working to a tight deadline: The teams worked in parallel, building the tower, pre-assembling the hub, and preparing the ground equipment for the crane on a dedicated hardstand.”

This WEC is the first E-126 in the fleet of the Stadtwerke Emden (SWE) utility. SWE Managing Director Remmer Edzards emphasised that the E-126 with its estimated yield of 20 million kWh will significantly contribute to an efficient power supply to the city; and its goal of going 100 % regenerative.

Currently, in the Estinnes wind farm in Belgium five out of eleven planned E-126 wind energy converters have been completed, the world‘s most powerful wind turbine to date. On 25 November, wind farm operator WindVision has marked this occasion with a big inauguration event.

The logistics to install the 198 m wind turbines touch the limits of today’s state of the art engineering: the world‘s largest crawler crane, a 1.600 t crane, was developed and constructed especially for lifting the giant 127 m diameter rotor in one step. “The E-126 wind turbine comprises the most advanced power electronics in use in the wind energy sector and is able to provide grid stabilising ancillary services which before were reserved for conventional power plants. Finally, to allow for an optimal integration of the produced electricity into the grid, advanced power prediction technologies are applied,” Piebalgs explained.

ENERCON began its road to economical/ecological success when graduate engineer Aloys Wobben founded the company in 1984. A small team of engineers developed the first E-15/16 wind turbine with a rated power of 55 kW. In the beginning ENERCON systems still featured gearboxes. The changeover to gearless technology was made in 1992 with the first ENERCON E-40/500 kW. The innovative drive system with few rotating components enables almost frictionfree energy flow. The performance and reliability of this system is exemplary. Mechanical stress, operating costs and maintenance costs are reduced, and the service life of the systems is increased.

ENERCON has been setting new standards for technological design for more than 25 years. As one of the world’s leading companies in the wind energy sector and the longstanding leader in the German market, ENERCON directly or indirectly employs over 12,000 people worldwide.

The annular generator is of primary importance in the gearless system design of ENERCON wind turbines. Combined with the rotor hub it provides an almost frictionless flow of energy, while the gentle running of fewer moving components guarantees minimal material wear. Unlike conventional asynchronous generators, the ENERCON annular generator is subjected to minimal mechanical wear, which makes it ideal for particularly heavy demands and a long service life.

The ENERCON annular generator is a low-speed synchronous generator with no direct grid coupling. The output voltage and frequency vary with the speed and are converted for output to the grid by a DC link and inverter. This achieves a high degree of speed variability.

With more than 14,500 wind turbines installed in over 30 countries, ENERCON is also amongst the leading manufacturers on an international level. Research and Development, as well as Production and Sales are continuously being expanded. In 2009/2010, Enercon reached an export share of more than 60%, gradually increasing over the years to come.

Enercon: Number of installed wind turbines: more than 15,000. Total power: more than 19 GW.