Modeling, Analysis and Control of a Chain Cell Converter

Chain cell converter as a shunt connected, multilevel voltage source converter has been proposed for static VAR compensation. This converter consists of identical H-bridge building blocks (HBBBs) connected in series in each phase. Chain cell converter synthesizes a desired ac waveform from several levels of DC voltages provided by the DC capacitors with only one switching per cycle. The transient model of the converter is developed considering a three phase three wire system. The analysis and design of converter controls is presented. DC voltage balancing strategy which involves pulse swapping is implemented. Simulations are carried out for the performance evaluation of converter controls. Chain cell converter is also tested, when connected in a distribution system, as a STATCOM to compensate the voltage flicker due to an arc furnace load.