| dc.description.abstract | This thesis aims to provide a reliability and maintenance analysis of marine hybrid power systems and figure out the effect of vessel operation contexts and system redundancies. The Multi-phase Markov method is implemented to introduce the factors of all operation modes, and the block replacement policy is applied for maintenance decision-making considering different working conditions. The results show that after introducing all the operation modes, the reliability result of the studied case regularly fluctuates between 0.9965 and 0.9985. Dynamic positioning mode is the relatively dominant factor influencing the lower bound of reliability. Different operation modes have different levels of Mean Time To Failure (MTTF). The differences among MTTFs can reach nearly 4000 operation hours, even though the differences in reliability are pretty slight. This can further influence maintenance strategies, which may not be apparent from the reliability calculation. Therefore, it is necessary to consider operation profiles for reliability modelling in the design and operation planning phase. In addition, increasing system redundancies can improve reliability performance and decrease maintenance work. However, the benefits are convergent. The improvement will not be significant when the redundancies increase beyond three components or units connected in parallel. For block replacement policy, the ratio of preventive maintenance cost and corrective maintenance cost and the shape parameters of the Weibull distribution are the dominant factors influencing the lower bound of the reliability under maintenance behaviour; to be more specific, the reliability lower bound drops with the increase of the ratio, but to increase with the rise of the shape parameters. Though the methods used in this thesis work very well, their disadvantages are apparent; the analysis is insufficient due to some assumptions set for simplification. Therefore, the balance between redundancies, reliability performance and the total cost should be further investigated in more detail in future studies. | |