Reliable and effective operation of electric power systems is connected with a solution of a lot of inter branch problems of electric power energetics, to which, in particular, the problem of the electric power quality (EPQ) is of main concern. The reason of its occurrence was the growth of electric power consumption in industry and household activities, improving and development of electro technologies, the appearing of new kinds of an electric equipment and significant increase of an amount of an electric equipment, consuming the electric power with transformed parameters in factories and household activities. In connection with this, the negative mutual influence of power systems and consumers on the electric power quality in networks has increased up∗ to appreciable sizes. Eventually, this worsens the operation of power systems as a whole. It determines an urgency of solving the electric power quality problem in power systems.