Inter-turn Short Circuit Fault Identification of Salient Pole Synchronous Generators by Descriptive Paradigm

Abstract

The field winding inter-turn short circuit (ITSC)fault is the most prevalent fault type in salient pole synchronous generators (SPSG) and can cause severe accidents and service outages. When the number of shorted turns is not high, an ITSC does not significantly change the magnetic field distribution; therefore, it is difficult to detect. Consequently, a sensitive method is required to diagnose ITSC faults in the early stage. In this paper, the air gap magnetic field and stray magnetic field are utilized for fast ITSC fault detection. Fault detection based on the stray magnetic field is confirmed as superior to that based on the air gap magnetic field. A novel method based on time-frequency analysis is introduced to detect the fault during steady-state operation. The proposed method is verified experimentally on a 100 kVA SPSG. A field test is carried out to demonstrate the applicability of the method in a power plant.