Three-phase asymmetrical load-flow

Abstract

This paper deals with the three-phase asymmetrical load-flow problem. It presents a solution of this problem in the sequence domain, which is more efficient than standard solutions in both the phase and the sequence domain. It specially copes with the asymmetrical states of unbalanced power systems. The efficiency is achieved by introducing the following basic advancements of the standard asymmetrical load-flow calculations: (1) elimination of phase-shifts from the sequence circuits of three-phase transformers; (2) enhancement of the standard classification of power systems buses to provide a correct treatment of Q limits enforcement; (3) synthesizing of buses of the generators and step-up transformers in the transformers high voltage buses; thus, reducing the form of the three-phase asymmetrical load-flow models to the form of symmetrical models. The efficiency of the presented solution in memory, CPU time and robustness is confirmed on the basis of several examples.