A harmonics optimized 12-pulse STATCOM for power system applications

Multi-pulse gate turn-off thyristor based voltage source converter (GTO-VSC) topology having a number of 6-pulse VSCs as elementary unit together with fundamental frequency mode of GTO gate control are widely used in STATCOM for dynamic reactive power compensation in electrical network. A 12-pulse topology generally produces an AC output voltage waveforms which contain 11/sup th/, 13/sup th/, etc. harmonics and hardly find its application due to higher total harmonic distortion (THD) level. In this paper, a new model of 2-level, 12-pulse, 132 kV, /spl plusmn/100 MVAr STATCOM employing 2/spl times/6-pulse GTO-VSCs, fundamental frequency gate switching, PI-control methodology, DC capacitor as an energy storage and two stages of magnetics, is designed and simulated to attenuate harmonics of the order of 5/sup th/, 7/sup th/, 11/sup th/, 13/sup th/ etc. by SimPowerSystems toolbox in MATLAB environment. The operating performance of the compensator is studied for regulating voltage and power factor correction in electrical network and results show the model acceptable for power system applications.