Wind Energy Systems - Wind Energy Systems for Electric Power Generation - page 108

Fig. 5.30 Self-excited induction generator with phase control
cost and increased losses. The grid-side inverter is a self-controled device, which al-
lows to control the power factor. A single-phase output is assumed. Further shown is
a passive filter to keep harmonics off the output, and a transformer to adapt the volt-
age levels of battery and grid. Note that the normal machine operation is supplying
active power and consuming reactive power, i.e. in the III. quadrant.
For an induction machine used as generator in a stand-alone system, two control
concepts may be used:
Fig. 5.31 Stand-alone system with cage induction machine and battery storage