Design and implementation of a DSP-based shunt active power filter in three-phase four-wire system

The implementation and design issues of a shunt active power filter with consideration for the unbalanced load is presented and analyzed in this paper. In real active filtering applications, digital controllers are preferable to analog controllers. A digital controller using a DSP based on synchronous reference frame is developed for the shunt active filter. Furthermore, using vector analysis in 2-phase α - β reference frame, the critical value for the DC side capacitor voltage has been derived to guarantee satisfactory compensating performance. Experimental results obtained from a 20 kVA prototype verify the viability and effectiveness of the shunt active power filter.