Posters

Abstract

Biggest offshore wind turbine is increasing in size and might reach 20MW in next few years. Going forward, fewer turbines would be needed to achieve the same output power of the wind farm. It places greater emphasis on the reliability of the components, FIT (Failure in time) rate and the number of components needed for the design. We are crossing a threshold of unit power beyond which the change from low voltage (LV) systems to medium voltage (MV) becomes an attractive solution due to its smaller footprint and need of reduced number of components. Medium voltage converter for 15MW has a footprint of less than 5m2 in a flexible configuration to allow easier integration into the wind turbine. 15MW prototype converter uses existing state of art 48 IGCT (Generation 2 IGCT, 85 mm pole piece). Efficiency of 98% has been achieved for the 15MW IGCT based medium voltage converter. Evaluation of IGCT field data from wind application as well as medium voltage drive applications results in FIT rate well below 100 failures in 109 device hours. Solution for 20MW can be achieved by using generation 3 of IGCT which enables scaling of both output current and voltage to achieve higher power levels without increasing the number of semiconductors. This is achieved by higher maximum Junction temperature (125°C to140°C), lower thermal resistance (8.5 K/kW to6.8 K/kW) and increased turn-off capability (5.5 kA to6.5 kA). This technology allows scaling to higher blocking voltages (products: 4.5kV, 6.5kV, prototypes 8.5kV).