Enhancing Distribution System Resilience through Line Hardening and Integration of Variable Renewable Resources

Line hardening in power distribution systems reinforces the network, significantly reducing the probability of faults during extreme events. The advantages of line hardening are particularly evident in mitigating power outages in radial distribution systems. In this paper, we propose a comprehensive strategy that combines hardening with a microgrid formation methodology to enhance resilience against the most severe N-k contingencies. The microgrid formation method utilized ensures that microgrids are interconnected through hardened lines but are not capable of sustaining islanded operation independently. Instead, the power supply to each microgrid depends on one or more interconnected microgrids, utilizing variable renewable energy resources to maintain functionality in islanded conditions. To minimize load loss costs during severe N-k contingencies while incorporating hardening measures, a two- stage optimization model is formulated. This model integrates Bender’s Decomposition (BD) and an iterative relaxation method (IRM) within a multilevel optimization framework. The proposed approach is validated using the IEEE test bus system, highlighting its effectiveness in reducing the impacts of severe contingencies on the distribution network.