Novel indices for power quality measurement

Power quality indices and the corresponding measurement techniques are utilized to quantitatively present the quality of power supply, and characterize and compare the negative impacts of different disturbances to power networks. To overcome the limitations, deficiencies and difficulties of the practical application of power quality indices and measurement techniques in common use, a set of three new indices are proposed In this work to summarize the time varying waveform distortion in an intuitive, comprehensive and highly efficient way. Moreover, a novel time frequency transform is also developed for the first time to continuously and accurately monitor the instantaneous frequencies and amplitudes of specific signal components in the nonstationary power disturbance, and then update the PQ indices in real time.