Doubled wind turbine officially started up
A 20kW wind turbine that uses an inverter one third the usual size, and also demonstrates the capability for motors, has just been officially started up.
The basic idea, originally revealed in Eureka's August 2007 edition, is to have two generator stators with different numbers of poles, fed and working at two different frequencies. One set of stator windings is directly attached to the mains supply and the other to the inverter.
Research on what is termed a Brushless Doubly-Fed Induction Generator started in 1999 and the 20kW machine on the West Cambridge site, a short walk from the University of Cambridge Department of Engineering Laboratory that developed it, is intended as a demonstrator. The absence of brushes and slip rings, additionally enhances reliability.
As well as the 20kW demonstrator, which has been running in test mode for some time, developer, Wind Technologies Limited, now spun out of the University, is developing a 600kW BDFIG to be retrofitted in an existing 600kW wind turbine at a test site in Grevenbroich, Germany, working with Windtest Grevenbroich.
The technology also works in the reverse direction, greatly reducing the sizes of inverters required to drive motors. Commenting that the turbine seemed to going at a good speed even though there happened to be no wind on the day of the startup event, it was revealed to us that on this particular occasion, the turbine was in fact being run from the mains in motor mode.
