IMPROVED 3-PHASE LOAD FLOW USING PHASE AND SEQUENCE COMPONENTS

The single-phase load flow is efficiently optimised for the rapid solu tion of power flow and voltages in large systems. The three-phase load flow, at present treated simply as an extension of the single-phase l oad flow, is to calculate asymmetry at frequency throughout the transm ission system. A new three-phase load flow, radically different from t he single-phase load flow, is proposed. The new load flow is more suit ed to the analysis of power quality problems in the transmission syste m. A mixed combination of sequence and phase component mismatches is u sed, with emphasis on robust convergence rather than speed. It is show n that the three-phase load flow will find one of two solutions at eac h load busbar, one of which corresponds to abnormal levels of zero seq uence voltage. The abnormal solution can be avoided by ensuring a path for zero-sequence current from the load.