A novel linear controller for grid connected doubly fed induction generator (DFIG)

Abstract

The advent of rising electrical energy consumption gave rise to a steady increase in the demand on power generation. So, in addition to conventional power generation units a number of renewable energy units are increasingly being integrated into the system. A wind electrical generation system is the most cost competitive of all the environmentally clean and safe renewable energy sources in world. The stator of the wind energy conversion systems generally Doubly Fed Induction Generator (DFIG) is directly are connected to the grid through Voltage Source Converters (VSC) to make variable speed operation possible. The stator of the generator is directly connected to the grid while the rotor is connected through a back-to-back converter which is dimensioned to stand only a fraction of the generator rated power. The rotor side converter (RSC) usually provides active and reactive power control of the machine while the grid-side converter (GSC) keeps the voltage of the DC-link constant. In the linear controller for DFIG, a vector-control scheme for the grid-side PWM converter and Instantaneous Reactive Power Theory(IRPT) for rotor-side PWM converter is applied. The proposed model of the linear controller and the conventional linear controller using Synchronous Reference Frame Theory(SRF) are both simulated in MATLAB/Simulink platform. A comparative study is done between the linear controller using SRF theory and the proposed linear controller in order to show how the proposed linear controller improves the performance of the grid connected Doubly Fed Induction Generator (DFIG).