Study on power factor through the similarity of waveform

With the rapid development of electric electronic technology, non-linear loads, large capacity converters, etc. increase mostly, which brings about the serious problems such as harmonics. Thus, the traditional power theory based on the average is unable to meet with the practical require. In this paper, the power definition in the sinusoidal and non-sinusoidal circuit is discussed and the waveform similarity between voltage and current is analyzed due to the criterion of minimum mean square deviation. Furthermore, the relationships among the waveform similarity factor, displacement power factor and real power factor are also discussed. The results show that power components are well analyzed in use of waveform similarity under the conditions of non-sinusoidal. At the same time, waveform similarity provides a simple but effective method for the calculation of power factor.