Reliability Evaluation of On-load Tap-changers Based on Multi-state Multi-Valued Decision Diagram

A Multi-state Multi-valued Decision Diagram method is used to effectively evaluate the reliability of on-load tap-changer including the complexity of the structure, the number of bottom events and the component polymorphism. Based on the analysis of the state of the on-load tap-changer module, the typical failure mode, the cause of the failure and the reliability evaluation model are established. The reliability of the system is qualitatively and quantitatively analyzed by using the Multi-state Multi-value Decision Diagram, analysis of the probability of system failure and the probability that the on-load tap-changer is in each fault state. Finally, component failure and failure mode are combined to analyze the probability importance of each component, and the reliability of each fault condition of the tap-changer is evaluated. The evaluation example shows that the proposed method can realize a clear deduction and reasoning of the fault mode of on -load tap-changer, find the weak link in the process of operation and reflect the influence of each fault mode to the system. The reliability level of the on -load tap-changer during the operating process can be effectively evaluated.