Wind energy has mushroomed into a mature and booming global green business while generation costs have fallen dramatically. Modern wind turbine technologies have been improved significantly in their power rating, efficiency and reliability. Global wind energy capacity is up to 196.6 GW at the end of 2010. This Chapter covers
∙ mathematical models for wind turbines such as wind turbine (WT) with doubly fed induction generator (DFIG) and WT with direct-drive permanent magnet generator (DDPMG);
∙ small signal stability analysis and nonlinear control using power electronic back-to-back converters, which are very similar to those of UPFC and VSC HVDC;
∙ dynamic equivalent modeling of wind farms;
∙ and wind farm interconnection with power grid via VSC HVDC link.