Reconsideration on Capacitor Ripple Voltage of CHB-StatCom: Observation, Modeling, Analysis, and Application of Ripple Effect From Design Perspective

The
ripple effect
phenomenon wherein the capacitor ripple voltage generates the fundamental-frequency output ac voltage of a cascaded H-bridge-based static synchronous compensator (CHB-StatCom) is revealed and investigated in this work. First, an observation method of the
ripple effect
for the CHB-StatCom is presented. Then, the reason why CHB-StatCom has a
ripple effect
is explained. Subsequently, the accurate mathematical model of the CHB-StatCom considering
ripple effect
is reformulated. Based on the remodeled mathematical model, the cognition inaccuracy of the conventional design of a CHB-StatCom is analyzed, and a new cost-majorization-oriented (CMO) design principle is proposed to optimize the cost of CHB-StatCom. The proposed CMO design needs a lower dc-link voltage to generate the same maximum fundamental-frequency output ac voltage compared with the conventional design, thereby reducing the cost of CHB-StatCom. The simulation and experimental results validate the correctness and effectiveness of the analysis.