Suppressing effect of fault current limiter on shaft torsional torque of synchronous generator in consumer system

We have investigated the influence of a fault current limiter (FCL) upon the relationship between the electrical air-gap torque and the shaft torsional torque of the synchronous. generator in a consumer system connected to a 6.6 kV utility distribution system. We found that the suppression mechanism of the shaft torsional torque was classified by a natural oscillation frequency of the synchronous generator. It was shown that the suppressing effect on the maximum value of the shaft torsional torque tau(sm) is largely determined by limiting of the average value of the electrical air-gap torque tau(e). In case that a natural oscillation frequency f0 of the synchronous generator is small. For higher f0 being close to a system frequency, it was shown that it is useful for the suppression of the tau(sm) to suppress the the instantaneous value of the tau(e) .