Identification of the Radial Configurations Extracted From the Weakly Meshed Structures of Electrical Distribution Systems

The electrical distribution systems are typically structured as weakly meshed networks with multiple supply points, but they are operated with radial configurations by opening the redundant branches. The nonregular composition of the meshed structure and the constraints imposed by the number and location of the supply points complicate the problem of determining all of the possible radial configurations that can be extracted out of a given structure. This paper illustrates a novel procedure, based on the creation of a reduced network structure, to determine the number of possible radial configurations and the set of open branches corresponding to each radial configuration. The proposed approach is presented and applied to five test distribution systems commonly available in the literature, providing for the first time the information about the number and the layout of the possible radial configurations obtainable for these systems.

I. Introduction

Let US consider an electrical distribution system operated at the medium voltage (MV) level. The system is generally supplied from the high-voltage (HV) side through one or more transformers located into the HV/MV substations and serve a number of load points, located at the MV nodes of the network, through a number of branches (e.g., overhead lines, underground cables, or transformers). Considering all of the branches that are installed to connect some pairs of nodes, the resulting structure is weakly meshed. However, in order to simplify the protection schemes, the distribution systems are traditionally operated with radial configurations by opening a number of redundant connections among the installed branches. The number of possible radial configurations depends on the number of supply points, the total number of nodes of the distribution system, and the topology of the distribution system, e.g., the physical links among the nodes through the existing branches. The basic rules for forming the radial structures are that any radial configuration starts from a single supply point, no load point has to remain isolated and each load point has to be connected to its supply point through a unique path. It is then necessary to identify in the whole weakly meshed network structure a suitable set of redundant branches to open. The generation of all of the possible radial configurations that can be extracted out of a given structure is a challenging task that is strictly dependent on the location of the branches. In fact, the absence of regularity in the topology of the distribution systems does not enable applying simple explicit formulas for enumerating or generating the radial configurations.