Harmonic analysis is one of the most important subjects of electric circuit's theory and power quality. In order to operate in optimal conditions which ensure the quality of power supply to consumers, each national power system must respect several operation standards limits and regulation. In this regard this paper introduces the relative values of voltage harmonics which are used as input data into an original algorithm to analyze the dependence between the voltage harmonics and power factor. A Matlab application is implemented and the results are discussed and compared with standard limits.