Online power quality measurements and voltage sags analysis

The Faculty of Electrical Engineering in Osijek and HEP d.d. - Croatian Grid Company are partners in the EU project Leonardo Power Quality Initiative (LPQI). One part of activities carried out within that project includes measuring, analyzing and statistical data processing of power quality indices. This paper presents the result of online power quality indices monitoring at HEP Distribution System Operator in TS 110/35 kV Osijek 2 at the secondary side on one of two transformers which supply the urban cable network in the city of Osijek. Power quality indices were measured with a three phase power quality network analyzer QWave Power CO. Voltage events were classified according to the EN 50160 and IEEE 1159-1995, and RMS variation performance indices were calculated.