Abstract
Power electronics devices are widespread in different engineering systems for housing and public utilities. But they have negative impacts to the power source. A typical example is using of the pumps operated by variable frequency drive in boiler stations and heating substations. The using helps both the energy savings and the voltage waveform distortion. If boiler station is supplied by emergency generator the voltage waveform distortion significantly increases. Voltage quality parameters are analyzed using a simulation model, built in MATLAB/Simulink, in different situations. The recommendations to ensure the specified voltage quality in the power supply system are created.