Three-phase four-wire shunt active filter to reduce voltage and current distortions in distribution systems

This paper proposes a shunt active filter (SAF) to reduce voltage distortions, caused by resonances between capacitances and inductances on three-phase four-wire low-voltage power distribution system, to below the recommended level by IEEE Std. 519-1992. In addition, there is a reduction of neutral currents caused by non-linear loads in this system. A detailed analysis of the normalized discrete model of the SAF is presented considering its implementation in a DSP TMS320F2812. Furthermore, the extension of the voltage detection method and the deadbeat current control applied to four-wire systems are proposed. Finally, experimental results are presented from a 20 kVA operating prototype, demonstrating performance in terms of voltage harmonic compensation at the point of common connection and the neutral current reduction.