A Detailed Comparative Analysis of Different Multipulse and Multilevel Topologies for STATCOM

Compensation of reactive power in a long transmission line is carried out using flexible ac transmission system (FACTS) devices like static synchronous compensator (STATCOM). In conventional STATCOM more then one voltage source inverters arranged together in zigzag fashion of transformers; arouse some problems, such as controlling issues, higher loss, extravagant, and unreliable. This paper deals with comparative analysis of five different power inverter topologies for the implementation of STATCOM: three multilevel topologies (five level, seven level, nine level) and two multipulse topologies (six pulse, twelve pulse). The study focuses on device count, total harmonics distortion (THD) measurement in phase voltage, fourier analysis (FFT) etc. More prominence is given to THD measurement due to its impact on line losses and cost of the STATCOM. A comparative analysis of each configuration based on its input DC voltage, THD, V
_RMS
, number of switches and H-bridge requirement etc. have been presented here. Level shifted PWM control technique has been employed for multilevel configuration.