Using Fourier transform and model based filters to measure time-varying harmonics

Power quality problems have become an important issue in electrical power systems design and operation. Therefore, methods to identify and quantify these problems are receiving increased attention. A good deal of those methods rely on the time-varying phasor description of power system currents and voltages. This paper is an attempt to summarize two established processing techniques to obtain these quantities based on a time sampled data stream. The first class of methods is based on the Fourier transform, whereas the second is model based. Finally, references to new processing techniques are given.