A new protection scheme for stator faults in synchronous generators

A new voltage controlled overcurrent protection scheme is proposed which is a backup protection method for differential protection. This scheme which is realized by fuzzy controllers is considered to be mounted beside a differential protection system, which operates in the cases that differential protection is unable to detect the fault. This novel protection scheme operates by adjusting the plug setting of the overcurrent relay that sends the trip signal to three-phase breaker. In the proposed method fault occurrences can be determined regardless of variations of voltage and current of terminal in different working states of synchronous generator. This is done by measuring other variables than those used in conventional protection methods. To demonstrate the proposed method, a synchronous generator with internal fault model is used. Numerical simulations validate the functionality of this novel scheme under different conditions.