Model-based On-line Protection Method for Brushless Synchronous Generators

A broad variety of electrical faults can take place in the rotating elements of brushless alternators, but these are difficult to detect due to the lack of available measurements. Therefore, this paper presents a new on-line protection method for brushless synchronous machines based on the comparison of the measured exciter field current with the theoretical current calculated from the stator voltages and currents for the actual operation point. The proposed method is able to detect interturn faults in the field winding, diodes failures or exciter faults. The method has been validated by experimental results using a special assembly based on a laboratory synchronous machine where open-diode faults have been performed.