A practical risk analysis for reliability improvement of distribution grids

Electrical distribution networks are going through a phase of significant changes from both technical and regulatory points of view. For example, load and coincidence factors change due to the high penetration of distributed generators and loads such as electric vehicles, heating, ventilation, and air conditioning systems, induction stoves, and customer behavior changes. Furthermore, many countries are introducing performance-based regulations, pushing distribution system operators to be more aware of selecting investments to improve the system efficiency and the quality of service for customers. In order to do that, distribution network planners should find best practices to evaluate ex-ante the main critical issues and periodically update the status and benefits of investments. In this paper, a risk index is proposed to estimate the reliability of distribution grids. Using a suited algorithm, automatic calculation of the index has been carried out on Milano's medium voltage distribution network, a city in the north of Italy, showing its correlation with the traditional reliability indices. Moreover, benchmark values for the index are given as well as some suggestions for reliability improvement.