Decaying DC offset removal operator using mathematical morphology for phasor measurement

Phasor measurement is an essential component of protection relays and phasor measurement units. Phasor measurement as performed by the Fourier Transform is adversely affected by the decaying DC offset which occurs following a fault. Hence an efficient mathematical pre-processor is proposed to remove this offset in a half cycle plus an additional sample. Following this it is possible to use a new phasor measurement technique which can estimate the phasor using a quarter cycle window. The results show that the mathematical preprocessor can virtually remove the DC offset, and that the new phasor measurement technique out performs the Fourier Transform due to its significantly shorter delay.