Optimal Hybrid Maintenance Policy for Protection Systems With Multiple Abnormal Operational Behaviors

We propose a three‐phase hybrid maintenance policy model for protection systems that exhibit abnormal operational behaviors, including misoperations and refusal operations. This policy governs routine periodic inspections and incorporates four categories of replacement strategies: corrective, inspection‐preventive, opportunistic‐preventive and scheduled‐preventive replacement. We focus on a non‐repairable single‐unit protection system subject to continuous degradation. System degradation is modeled using the delay‐time theory. The occurrence of system misoperations or refusal operations depends not only on the arrival of disturbance or mission signals but also on the system's state at the time of signal arrival. The arrival of these relevant signals follows a Homogeneous Poisson Process. Additionally, we account for the imperfection of periodic inspections in our modeling. To identify the most cost‐effective maintenance policy, we adopt an enumeration algorithm, and we introduce a simulation procedure to validate the correctness of the proposed model. Numerical analysis demonstrates that our three‐phase maintenance strategy can serve as an effective decision‐support tool for the maintenance practice of protection systems.