Analysis of Hybrid Cascaded Multilevel Converter based STATCOM

A new Static Synchronous Compensator (STATCOM) based on the Hybrid Cascaded Multilevel Converter (HCMC-STATCOM) is presented in this paper for the sake of decreasing the number, size and stored energy of the capacitors used in the STATCOM. The HCMC-STATCOM is comprised of one conventional three-phase two-level converter and one Wave-shaping Circuit (WSC) consisting of cascaded H-bridge Sub-modules (SMs). An in-depth analysis and design of the capacitor parameters is done to reduce the cost and footprint of the HCMC-STATCOM. Moreover, a detailed comparison between the HCMC-STATCOM and the conventional Cascaded H-bridge STATCOM (CHB-STATCOM) is made, which proves that the number and stored energy of the capacitors in the HCMC-STATCOM are obviously smaller than that of the CHB-STATCOM. Finally, a 35kV/±100Mvar HCMC-STATCOM mode based on PSCAD/EMTDC is established and then the technical feasibility of the proposed topology and the accuracy of the theoretical analysis are verified.