A DETAILED R-L FED BRIDGE CONVERTER MODEL FOR POWER-FLOW STUDIES IN INDUSTRIAL AC DC POWER-SYSTEMS/

Because of lower voltage levels and smaller power ratings, the R/X rat io of commutation impedance in industrial ac/dc distribution systems i s usually higher than that in HVDC transmission systems. Considerable discrepancies may, therefore, incur in industrial ac/dc power flow res ults, especially the reactive power consumption of converters, if the commutation resistances of converters are neglected. To describe the e ffects of commutation impedance on converter operations and to precise ly relate the fundamental line current and de output current of the co nverter, a detailed model of the bridge converter with commutation imp edance for use of Newton-Raphson power flow studies in industrial ac/d c power systems is derived in this paper. A coal mine power system and a de electrified transit railway system with regenerative braking fun ction, a part of Taipei Rapid Transit Systems under planning, have bee n analyzed to show the improved accuracy and good convergence characte ristics of the developed Newton-Raphson power flow formulation with th e proposed converter model.