An Investigation of the Influences of the Voltage Sag on the Doubly Fed Induction Generator using Tuned PI Controllers

The paper presents dynamic and transient behavior of the doubly fed induction generator (DFIG) in the wind farms in the normal and faulted grid respectively. When Voltage sag or any fault occurs in the network, the variables in the Doubly Fed Induction Generators are varying severely. If a voltage sag occurs, active and reactive power generated by the DFIG start to oscillate. The DC-link voltage will be bigger and will have fluctuation, and the rotor current will increase. In this paper, proportional integral (PI) controllers are used to control the DFIG in the wind farms for driving of the electronic devices including Rotor Side Converter (RSC) and Grid Side Converter (GSC) and controlling the active and reactive power of DFIG. PI parameters are tuned by particle swarm optimization algorithm (PSO). Whereas the model of DFIGs and electronic device in the paper are nonlinear so PI controllers cannot protect and control the DFIG as well. Hence, effect of PI parameters is investigated on the DFIG with simulating in MATLAB software. Also, low voltage ride through (LVRT) feature for DFIG is explored in presence of PI controllers. The results of the simulation present DC-link over voltage and rotor and stator over current in the DFIG. In addition, it will explore the effect of proportional integral controllers when three-phase short circuit fault Occurs.