A bi-objective maintenance scheduling for power feeding substations in electrified railways

• A bi-objective maintenance schedule model is proposed for railway feeding stations.
• System reliability and cost models are given over maintainability.
• Five methodologies for scheduling problem are combined to search effective solutions.
• Evaluation on the scheduling model and solution is implemented through simulation.
• Impact of weighting factors between reliability and cost on schedules is discussed.

Railway infrastructure is characterized by intensive capital investment, long lifecycle and low return. It is crucial to attain a reasonable system reliability while keeping the recurrent cost manageable throughout the asset lifecycle. Power feeding substations are the key assets on electrified rail lines. As they are subject to various adverse operating conditions, maintenance works of different levels are scheduled to ensure reliability and extend the asset life time if possible. Maintenance scheduling is often regarded as a trade-off between reliability and cost. This study incorporates considerations of different levels of maintenance activities to balance between reliability and cost. In establishing the system reliability model, the contribution of individual component reliability toward the overall system reliability is extracted from the functional relationship among the components. Solution methodologies to this scheduling problem are also proposed here. Evaluation of the scheduling model and the proposed solution is discussed and analyzed through simulation. To cater for the operating conditions in different systems, the impact of weighting factors between reliability and cost on the variations of resulting schedules will be investigated.