Control Strategy for Cascaded Medium – High Voltage STATCOM

Abstract

Control strategy is researched for cascaded mediumhigh static synchronous compensator to provide syntheticcompensation ability of reactive power, harmonics andasymmetric currents. Basing on selective harmonic compensationstrategy, a reference current detection method utilizing thecombination of synchronous reference frame transformation anddiscrete Fourier transformation is proposed. The tracking controlof instruction current is implemented by multi-carrier pulse widthmodulation (PWM). In allusion to the multi-carrier PWM, thecapacitor voltage balancing control at the dc side is realized by atype of software based on the energy balance principle of theinverter bridge. The proposed control strategy is convenient forengineering implementation given its low calculation burden andsimplicity. The effectiveness of the proposed control strategy isproven by both simulation and experimental results.