Voltage and Current Analysis of Multi-step STATCOM Based on Three-Level Inverters

Assuming that STATCOM has no active power losses, the current and voltage analytical expressions of the three-level and dual three-point STATCOMs under the fundamental frequency modulation (FFM) control are presented by means of the theoretical analysis method. Meanwhile, the current and voltage waveforms of two STATCOMs are simulated with the help of Matlab/Simulink. The good agreement between theoretical analysis and simulation results verify that the proposed theoretical analysis method is valid and feasible, which can be extended to the analysis of similar power electronic circuits. The analytical and simulation results show at the same condition, the voltage and current harmonic contents of the dual three-level STATCOM can be effectively decreased compared with the three-level STATCOM, and the capacity of the dual three-level STATCOM can be increased.