Diagnosis of interturn fault in stator winding of turbo-generator

The synchronous generator is one of the most expensive and important components of power systems. Therefore, it must be protected against any fault. To prevent fault expansion, appropriate protection must be able to quickly diagnose generator internal faults. Meanwhile, protection system security depends on the stability of power system transients. One of the generator faults which may be undetectable by the existing advanced relays is the interturn fault. This paper introduces novel indices to detect this type of the fault which are based only on the measured current in the terminals of the generator. A quick algorithm can easily diagnose the fault. The merit of the algorithm is that it can detect the faults shorter than half of the cycle with correct operation. Furthermore, the proposed quick and secure approach has low computational burden and it can be simply applied to digital protection relays. To evaluate the performance of the proposed method, a high power synchronous generator is simulated using two-dimensional finite element method. Also, its performance is verified for distinguishing interturn fault from power system transients and phase-to-phase faults.