Currently, many loads are non-linear, and there is a trend to increase them. As is well known, nonlinear load generates harmonic components, resulting in a change of delivered power characteristics, namely, indicators degrade the supplied power quality. ln turn, the deterioration of the power quality leads to its overrun. Active introduction of high-tech equipment is accompanied by an increase in the proportion of customers’ special requirements for the quality of supplied electricity. In this regard, the problem of monitoring and reduction of the harmonic components is relevant. Timely and accurate measurements based on data recorders’ vector quantities with high resolution offer the prospect of continuous monitoring of the quality of power supply. This paper suggests a distributed system for monitoring the power quality by the use of available PMU infrastructure to carry out continuous control of the harmonic level in different cutsets of a power system.