Research on three-level SVG in the distribution network system

With increasing consumption of reactive power, the negative sequence component generated by unbalanced three-phase system has seriously affected the power quality, power system stability and economical operation. The distributed static Var generator (D-SVG) is one of the new high-tech devices which can stabilize the voltage and enhance the power factor for power system. Comparing with traditional two-level SVG, this type of SVG can work with higher voltage, larger output reactive current and lower device switching frequency. In this paper, aiming at the dynamic performance of the D-SVG, a dynamic mathematical model of D-SVG is established by the switching function method. Then according to the Instantaneous Reactive Power Theory, the D-SVG system is controlled by the Direct Current Control (DCC) Strategy.