Reactive power and unbalance compensation with DSTATCOM

Load unbalance is a general phenomenon in low-voltage three-phase distribution system. As the negative sequence voltage will cause abnormal operation of electric equipments and decrease the power quality, a low-voltage distribution static synchronous compensator (DSTATCOM) is proposed to compensate both the reactive power and load unbalance caused by asymmetric loads in a three-phase power system, and an asymmetric control method based on symmetrical component transformation and d-q transformation for the DSTATCOM is presented. An experiment system of a low-voltage DSTATCOM was developed, and the generation method of SPWM pulse was implemented. The results of experiments, which conducted with balanced load and unbalanced load, verify the validity of compensation algorithm, and also show that the SPWM-based DSTATCOM can compensate reactive power and load unbalance synchronously.