New invasive method for localisation of harmonic distortion sources in power systems

The presented paper illustrates the invasive method of power-system identification. It is based on Czarnecki's ideas to disturb slightly the system and observe its response to find unknown harmonic sources and equivalent linear impedances. The one-phase system is considered with a new signal-processing technique in which instant measurements are based only on two adjacent signal periods. That approach allowed to move differential calculations to the time domain, and to deal with integral Fourier transform, in place of discrete, infrequency domain. The new algorithm allows to increase the S/N ratio, is insensitive to signal time-shifts and gives correct results in a wide frequency band (5 kHz). Simulation and measurements results are presented and show how accurate the identification can be for short-time (two periods) and 1 s long observations.