Study of DC Short Circuit Fault & Protection of VSC-HVDC Based Off-Shore DFIG Wind Farm

This paper addresses DC short circuit fault of VSC-HVDC transmission system for off-shore DFIG wind farms. Proposed protection system actively mitigates the high circulating DC fault current with the help of snubber circuit. The proposed protection scheme consisting of snubber IGBT circuit connected in series with the conventional thyristor (AC Circuit Braker). The protection circuit has been examined with both the AC and DC fault. The IGBT snubber circuit segregate both the AC & DC part from the fault and helps to protect freewheeling diode of the converter stations. The normal operation of the whole system is restored within the 30 milli seconds fault clearing. All the simulation study and the whole model was built using the standard software MATLAB Simulink.