An evaluation of shunt active filtering techniques in the era of smart grids

This paper presents a comparative evaluation of two commonly used active filter methods. In the first method the active filter performance is based on injection of harmonic currents 180o out of phase with the harmonics produced by the non-linear loads that must be compensated. Therefore, the compensated line current is equal the 50/60 Hz positive sequence current. In the second method the line current is adjusted to have a waveform that is a replace of the voltage waveform. Thus, the non-linear load and the active filter perform like a unity power factor non-linear load. The preliminary results show that the second method is slightly more effective than the first method. It leads to less voltage distortion and reduced distribution line losses. Additionally, it is shown that the second method could be even more advantageous considering the supraharmonic currents generated by the actual distribution systems based on smart grids, modern electronic loads and distributed generation devices.