Large scale wind energy conversion system using DFIG in sub-synchronous and super-synchronous speed ranges

Soaring oil prices, Climate change and global warming have attracted attention of various researchers to look for different renewable energy options for generating electricity. Wind energy has become one of most sought after options among the different renewable energy resources due to the advent of power electronic based controllers that allow constant frequency voltage to be generated irrespective of the variations in wind velocity. The advantage of using DFIG for wind energy conversion systems is that it requires a power electronic converter rated only for slip power which is a small fraction of the total capacity of the generator. This paper envisages bringing out the analysis of a DFIG system in terms of its stator and rotor currents and real and reactive power balance when the machine is operating with varying wind velocity conditions. Vector control strategies are being employed for both the converters connected, in cascade, in the rotor circuit. Maximum power point tracking (MPPT) has also been implemented to harness maximum available power for a given wind velocity.