Abstract. This article observes maintenance problems of PWM-Electric Drive in Power Networks with distributed generation (DG). Compared to conventional centralized networks harmonics disturbances and non-sinusoidal waveforms happen faster in DG networks due to bigger amount of non-linear loads (Frequency and Power AC and DC Converters, PWM-Electric Drive, etc.). As a result, general stability, power quality and uninterruptible power supply can be disturbed. In order to prevent these factors a complex of power conditioning measures is proposed in this article. It demonstrates the possible influence of Active Power Filters with selective harmonics compensation function implementation together with developed controller and preventive algorithm. Almost all modelling was performed in Matlab/Simulink software.