Topological Vulnerabilities in Electric Distribution Networks: a Deterministic Approach Based on Graph Theory

Medium Voltage distribution grids have generally a meshed structure and they are radially operated. A meshed structure allows many Secondary Substations being supplied even if one fault affects its related feeder. However, some substations are supplied by topologically radial sections of the network, so even a single line fault leads to permanent user disconnection. These configurations can be classified as topological vulnerabilities and can be present in the network structure or can be caused by temporary unavailable branches (e.g., for maintenance or repairing activities). This paper presents a novel and efficient algorithm for the identification of topological vulnerabilities. In order to demonstrate the algorithm functionalities and robustness, it has been applied on a test network describing a real world distribution system. The collected results show that an unavailable branch leads to a mean increase of around 60% in the number of nodes supplied by a topological vulnerability. The algorithm has been successfully integrated into the Distribution Management System of the electric grid of the city of Rome and is running in real time. The service is relevant for the operators who want to increase awareness about the topological vulnerabilities.