This paper proposes a new methodology for shortterm (24 hours) reliability assessment of transmission and distribution networks, including detailed substations models. Substations are first considered as single electrical nodes to evaluate the reliability of delivery nodes. If nodes (substations) with a high LOLP (Loss of Load Probability) are identified in this preliminary analysis, the critical substations are modeled in detail to obtain the corresponding reliability indices with a higher

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... racy, especially the indices corresponding to delivery points (feeders). The proposed methodology includes a topological analysis module similar to the topological processor used in State Estimation, a DC Load Flow, a DC-OPF module to compute remedial actions, and a reliability evaluation module based on state enumeration. The proposed approach is flexible and easy to implement, and special efforts have been made to reduce the computational requirements and to present the results in a way appropriate to both operators and planning engineers.