The wavelet transform can be used in the electric signal processing under the situations of loss-of-excitation

oscillation and terminal shout-circuit fault of electric power generator. Through the simulation of a model by Matlab

some results are achieved and show that the amplitudes of voltage and current have obvious difference via wavelet transform under different situations of loss-of-excitation

terminal short-circuit and oscillation from the normal condition. Therefore

it’s possible to distinguish the situations of loss-of-excitation

terminal short-circuit and oscillation through presetting the amplitude limits of signals after wavelet transform in order to enable the trip signal immediately to send out when losing excitation only and lock the trip signal when short-circuit and oscillation is happening. It’s a new approach to intend to solve the erroneous operation of loss-of-excitation protection of generator.