Active and Reactive Power Control of DFIG using Optimized Fractional Order-PI Controller

Doubly-fed induction generators (DFIG) are widely in wind farms due to their ability to run at variable speed. Researchers are keen to overcome the implications of unbalanced wind energy on its active and reactive power output using bidirectional power flow pulse width modulation (PWM) converters. These converters incorporate slip power recovery methodology for regulating the power recovered from the wound rotor of the induction machine, or the power flow from the grid to convertors. This research paper has proposed a fractional-order calculus-based control mechanism for an optimized operation of proportional-integral controllers operated in fractional order domain in pulse width modulation converters for the output power regulation. A genetic algorithm is used to optimize the gains of this fractional-order proportional-integral controller. The proposed scheme helps in overcoming the transients and non-linearities occurring in the electrical grid due to variable wind speed. The time-domain analysis of the doubly-fed induction generator is expressed using an appropriate fitness function. A comparative analysis between conventional proportional-integral and fractional-order proportional-integral controllers tuned using pole-placement and genetic algorithm respectively confirms the efficiency of later technique by showing the reduced steady-state error of 1.44%, 0.63% and 0.11% for active power, reactive powers, and DC-link voltage, respectively.