Upstream bus-labeling technique for radial distribution networks

Many optimal bus-labeling methods have been proposed in order to improve the efficiency of computation of nodal admittance matrix in power systems and to save the computer memories. Regretfully, by these methods, new filling-in elements may appear during the elimination process of the nodal admittance matrix. For the distribution system computation, this paper proposes a new bus-labeling method called upstream bus-labeling technique (UBLT) on the basis of a deep analysis of the radial structure characteristics of the distribution systems. Its principle is that the bus number should be bigger than the bus numbers of its downstream buses or that the bus number should be smaller than the bus numbers of its upstream buses. By comparison between the static bus-labeling method and UBLT, it's known that no new filling-in elements occur by UBLT in radial distribution networks because the elimination process of nodal admittance matrix is in fact a nodal equivalence process. This paper also explains why there is no new element filling-in by UBLT from the viewpoint of mathematics and network in detail. A conclusion is drawn that the amount of computation is least by UBLT. The proposed UBLT can be used for power flow solution in distribution network.