Multi-Objective Reliability and Resilience Assessment of Electrical Distribution Networks Using Optimized Adaptive Protection and Fault Management Strategies

Abstract

Modern distribution feeders operate under changing demand, distributed generation, network reconfiguration, and increasingly demanding continuity-of-supply requirements. Protection systems must therefore do more than interrupt faults quickly: they must isolate damaged sections selectively and support the recovery of healthy loads. This article presents a multi-objective assessment framework that links adaptive overcurrent protection, fault management, customer reliability, and network resilience. The proposed application considers the IEEE 33-bus and IEEE 69-bus distribution networks under common fault and restoration conditions. Three alternatives are examined: conventional fixed-setting protection, adaptive relay-setting selection, and integrated adaptive protection with coordinated switching and restoration. Inverse-time relay characteristics and primary– backup coordination constraints are combined with the system average interruption frequency index, system average interruption duration index, annual energy not supplied, and a twelve-hour load-service resilience index. A hybrid particle swarm–grey wolf optimizer is proposed for identifying feasible trade-offs among clearing time, customer interruption, unserved energy, and restoration performance. For a transparent numerical comparison, the article uses stipulated scenario inputs rather than results from a completed feeder simulation. Within these scenarios, the IEEE 33-bus average clearing times are 0.64, 0.43, and 0.28 seconds for the three strategies. Corresponding interruption durations are 12.0, 8.3, and 5.7 hours per customer annually, while event resilience scores are 0.68, 0.81, and 0.90. The IEEE 69-bus resilience scores follow the same pattern at 0.62, 0.76, and 0.87. The comparisons illustrate potential benefits of coordinated decisions but do not independently verify the stated improvements. Practical application requires benchmark-data validation, short-circuit modelling, realistic device characteristics, secure communications, and feasible restoration paths. The framework provides a consistent technical basis for evaluating whether protection improvements translate into measurable customer-service benefits in active distribution networks. Particular attention is given to coordination security, correct interruption accounting, continuity for essential services, and the need to carefully test parameter uncertainty before practical deployment decisions.

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