Overvoltage protection scheme for back to back converter of grid connected DFIG

This paper deals with the behavior of DFIG under normal and abnormal condition of grid based on the parameters of DFIG such as power flow, stator and rotor current and DC link voltage. The stator side, rotor side and DC link are realized by their equivalent circuit for analysis under normal and dip condition. It is observed that during abnormal condition there is unbalance in stator and rotor current due to which DC link voltage fluctuates. To overcome this problem an effective solution is suggested in the term of DC chopper. The DC chopper integrates with DC link circuitry to control DC link voltage. An extensive digital simulation has been carried out using MATLAB environment in order to study the behavior of DFIG with DC chopper under normal and abnormal conditions. The satisfactory system performance proves the suitability of DC chopper for maintaining DC link voltage of DFIG.