For a number of years, the technology selection for wind turbine drive trains in China had closely followed the same steps as in Europe. Just recently, Chinese companies have leapfrogged ahead to the latest and most advanced modern drive train technology.
In the first phase of wind turbine technology development, local Chinese turbines were mainly built based on licenses from Europe. Therefore, induction generator based turbines were built originally. The first ones were based on a standard asynchronous machine and a soft starter; later on, drive trains advanced to feature a double-fed induction generator (DFIG) and converter. Finally, along with the shift into the new millennium, came a shift in technology towards new solutions represented by permanent magnet generators (PMG) and full-power converters (FPC).
When The Switch entered China in 2004, there were no PMG-based turbines in production. Yet some open-minded companies had that technology on their drawing boards. Over the past ten years, we have witnessed the PMG revolution in China.
In fact, all Chinese wind turbine manufacturers that have really been successful during the past ten years, and are still on top today, have selected PMG and FPC based drive trains in their turbines. They have been lucky to be able to leapfrog ahead to the most modern technology, since they were able to select their own turbine designs from scratch once the license phase was over.
As a comparison, just think about the shift in the type of converters used with DFIGs to the modern FPCs now used in industrial motor drives that took place many years ago.
The main reasons for PMG and FPC drive train success are high reliability and availability, combined with the ease of handling existing and future grid connection requirements, such as low voltage/high voltage ride-through. Drive trains with FPC can also handle requirements for feeding reactive power. DFIG machines cannot reach the same level without an external power conditioning device.
It is clear that the old designs will remain. But the majority of new designs in China are based on PMG and FPC. And these are now leading the way – and the world of wind power.
Reijo Takala
Vice President, Markets