Integrating electrical and aerodynamic characteristics for DFIG speed control study

A doubly-fed induction generator (DFIG) is a ´special´ variable speed induction machine widely used in modern large wind turbines. Unlike a fixed-speed wind turbine, a DFIG wind turbine depends on the controls of the system at both the generator and the wind turbine levels, and the operation of the turbine is affected by the electrical characteristics of the generator and the aerodynamic characteristics of the turbine blades. This paper presents a DFIG speed control study by combining the two characteristics together in an integrative environment. The generator characteristics are examined for different d-q control conditions, and the extracted power characteristics of the turbine blades are presented versus generator slip. Then, the two characteristics are analyzed in an integrative environment to investigate various factors that are critical for stable and effective DFIG speed control design. Extensive simulation studies are performed to illustrate DFIG operating properties affected by both wind turbine electrical and aerodynamic characteristics.