Unbalanced multiphase load-flow using a positive-sequence load-flow program

Existing commercial load-flow packages have the capability of solving large balanced transmission systems using little computer memory and processing time. Their computation efficiency overcomes the small imprecision caused by the modeling simplifications and assumptions made in both transmission and distributions simulation packages. However, the interest for modeling more accurately unbalanced multiphase networks and solving complex integrated transmission-distribution systems has greatly increased among the power system specialists. The present work develops an unbalanced multiphase load-flow algorithm with the capability to model all components and network features found in power systems. The proposed algorithm allows the use of any existing positive-sequence load-flow solver as the main engine. The simulation results validated with EMTP-RV and CYMDIST prove that the proposed methodology has good numerical accuracy, robustness and efficiency.