Load-Flow in Multiphase Distribution Networks: Existence, Uniqueness, and Linear Models

摘要

This paper considers generic unbalanced and multiphase distribution systemsand develops a load-flow algorithm based on a fixed-point interpretation of theAC power-flow equations. Explicit conditions for existence and uniqueness ofload-flow solutions are presented. These conditions also guarantee convergenceof the load-flow algorithm to the unique power-flow solution. The proposedmethodology broadens the well-established Z-bus iterative method, and it isapplicable to generic systems featuring (i) wye connections; (ii) ungroundeddelta connections; (iii) a combination of wye-connected and delta-connectedsources/loads; and, (iv) a combination of line-to-line andline-to-grounded-neutral devices at the secondary of distribution transformers.Linear load-flow models are then derived, and their approximation accuracy isanalyzed. Theoretical results are corroborated through experiments on IEEE testfeeders.