A foundation with sufficient stiffness to resist long-term wind and wave load to insure the serviceability of wind energy converter is needed.

By adding damp load at DC-side of the converter, redundant energy at DC-side during grid faults will be consumed, therefore the operating of wind turbine will not be influenced by grid voltage sags.

This thesis mainly discusses direct-driven permanent magnet synchronous wind energy conversion system (WECS) used back-to-back PWM converter.