Methods for providing generator stator winding ground fault protection

摘要

The present invention includes a method for providing ground fault protection to a generator. The method includes determining the existing state of the generator and second, determining the updated alarm or trip conditions of a relay connected to the generator in view of the existing state of the generator. This includes estimating a ratio of the magnitude of the 3^rd harmonic neutral voltage to the magnitude of the 3^rd harmonic terminal voltage of a generator, along with calculating the residual 3^rd harmonic voltage from the estimated 3^rd harmonic ratio. From this, a comparison is made between the energy of the residual voltage with a fractional energy of the 3^rd harmonic neutral voltage. Based on this comparison, an alarm or trip condition is signaled when the energy of the residual voltage is greater than the fractional energy of the 3^rd harmonic neutral voltage. The invention further includes adaptive relays and systems utilizing the adaptive relays, along with methods of producing power using the adaptive relays.