Rotary diode failure detection in brushless exciter system of power plant synchronous generator

Reliability and availability of synchronous generator in power plant is related to performance of exciter system that is coupled mechanically and electrically to synchronous generator. This paper focused on the condition monitoring of rotating rectifier diodes in brushless exciter. Two common types of diode failures such as diode open-circuit and diode short-circuit on the one branch of rotating rectifier are simulated during no load and full load conditions. All accessible signals of main generator and exciter are analyzed by FFT method. In the end best signals for detection fault condition are introduced and suitable criteria to distinguish between diode failures are presented.