Reduced top head mass without compromising reliability ABB, the leading power and automation technology group, introduced a new medium speed permanent magnet generator (MS PMG) for the full converter (FC) concept at the European Offshore event 2011 in Amsterdam. The generator design offers a reliable and compact solution for multi-MW offshore wind turbines.
New design adds value to the medium speed solution
The new semi-integrated medium speed generator covers the power range up to 8 MW and more. In this new modular design the generator and medium speed gear are integrated via a flange connection. Using separate drivetrain components results in low lifting weights and enables dismounting for servicing. For OEM’s, the new semi-integrated design offers a fast route to serial production of large offshore turbines. ABB built the first MS PMG for the “Multibrid-type” fully integrated design in 2000. This created the basis for today´s economical medium speed generators featuring low magnet mass even at multi-MW powers. The design is based on ABB´s proven technology and extensive experience in supplying low, medium and high speed PM generators since 1990s.
General benefits of using medium speed generators
Medium speed solutions deliver many benefits. A slower speed design is more reliable for large offshore powers and MS PMGs are also compact in size and offer low top head mass. Low weight means easier logistics as well as lower tower and foundation cost. MS PMGs offer the highest efficiency (>98 %) of any commercial wind generator design. Efficiency is also high at partial loads in low wind conditions and thus enables the largest annual production of kWh’s.
End customer view
Developers, utilities and finance providers demand proven products. The OEM’s track record and the cost of electricity produced over the plant lifetime are the crucial factors. Drivetrain selection is therefore one of the most important decisions to make. MS PMGs offer a reliable cost-effective solution enabling serial production for the offshore market.
Technology inside the system
A PM generator is a synchronous electrical machine where the rotor windings have been replaced with permanent magnets. The main benefits are high power output from a small size, high efficiency at all speeds and robust construction. The FC concept used with this solution decouples the generator from the grid and offers total control and advanced grid compliance.
ABB has established a strong reputation as a reliable supplier to the wind power sector. It is known for its proven generator – converter packages, as well as delivering a wide range of electrical components for the wind industry. Leading turbine manufacturers rely on ABB technology. An optimized product platform and large-scale manufacturing experience using powerful magnets enable ABB to offer competitive prices and fast delivery times. Over the last 30 years ABB has supplied around 30 000 generators for wind turbines, totaling some 30 000 MWs. It is also the leader in PM technology. ABB has over 120 years of experience in manufacturing motors and generators for all types of demanding applications.