STATCOM using packed U-Cell 5-level converter with new control algorithm

Abstract

This paper introduces a new control strategy for a single-phase 5-level packed U-Cell (PUC) converter that is used as a STATCOM. The proposed control method allows the regulation of the amount of reactive power (VAr) injected to the grid as well as the amount of active power that charges the capacitors to balance their voltages. The proposed control algorithm is based on a 4-carrier PWM technique and uses redundant switching states to control the amplitude as well as the phase angle of the grid current. As a result both reactive and active power can be controlled which assures good balancing of the capacitor voltages. The proposed method was implement and tested with simulation. Results obtained show that the capacitor voltages were balanced within 2% of their rated values and the grid current THD% was below 5%. These results validate the effectiveness of this method.