Winding Fault Diagnosis and Failure Prognosis Technique for Brushless Synchronous Generator

Abstract

Winding fault diagnosis and failure prognosis technique has been developed based on d-q model of brushless synchronous generator (BLSG) considering actual winding insulation degradation curve of machine in inter-turn fault, damper bar and field currents for various severities of inter-turn winding faults have been estimated using extended Kalman filter. For validation of damper bar currents, 2 D transient electromagnetic analyses using finite element method have been done, and 2nd harmonic component of damper bar currents for various severities of inter-turn fault in stator windings have been computed by Fourier transformation. The winding insulation degradation curve of machine has been determined by accelerated life test, and used for estimation of remaining useful life of machine under inter-turn fault, assuming a pre-defined failure threshold. Actual and predicted life of the BLSG has been compared. Wireless sensors using rotor telemetry system have been mounted on the rotor of BLSG for experimental validation of field currents under winding faults. The 2nd harmonic of damper bar currents increase with increase in severities of winding faults and do not get affected by diode failures in rotating rectifier, hence this can be used as a robust fault indicator for diagnosis and prognosis of inter-turn winding fault in BLSG.