The hilbert transform adaptation for measuring amplitude and phase low-frequency disturbances in power system voltage

Phase disturbances in electric power signals are neglected and only amplitude (envelope) distortions are discussed in a literature. Amplitude disturbances are interpreted as amplitude modulation (AM) of main 50 Hz frequency. Detailed analysis of all disturbances and their sources are presented in the paper. It is shown that AM and narrow band PM (phase modulation) take place in power network simultaneously and those two modulations interact with each other. Voltage variation is proposed as disturbances measurement. Theoretical results are verified by field experiments and their results are presented.