Rov.. there appears to be a misunderstanding here. Alternators such as those used in wind turbine electricity generators are normally of the self exciting type. They work like this, a little residual magnetism in the iron cores of the field coils is sufficent to generate a little current which is fed back to the field coils. This enables the generation of more current and so on until the field coils are working at full strength and the alternator is producing enough voltage and power to supply the grid. The use of permanent magnets instead of or as well as electromagnetic field coils means that at low wind speeds the need to use some of the power to feed the field coils is avoided so this power can be fed directly to the grid. There is nothing new in using permanent field magnets,they are used in bicycle dynamos, their drawback is that they are heavy, bulky and expensive.I suspect that siemens are using a hybrid system to get a bit more power at low wind speeds although sacrificing output at high windspeeds.