Operation-Based Reliability Assessment of Shore-to-Ship Charging Systems Including On-Shore Batteries

Abstract

In this paper, an operation-based reliability assessment framework is proposed for Shore-to-Ship Charging (S2SC) systems including On-Shore Batteries (OSB). The OSB is considered to support the grid under fast charging loads. By the proposed approach, the impact of operational planning on reliability is identified. The main operational parameters considered in the reliability analysis include the charging load power and the charging- and discharging scheduling of the OSB. A hierarchical reliability framework is established where the failure rates of the components are estimated based on the FIDES methodology for physics-of-failure-based reliability prediction. Then, a dynamic failure threshold is introduced to translate the component failure consequences to the system performance into three states – failed, normal, and de-rated operation. Hence, the failure threshold is obtained for a specific set of operational and system design parameters. Additionally, to benchmark the characteristics of the SoC profiles of the OSB, an operation-based battery lifetime analysis is conducted. The evaluation of system-level reliability and on-shore battery lifetime is carried out for a 4MW dc S2SC system with a specified range of operation parameters. The results show that batteries and the IGBTs in the power electronics converters are the most reliability-critical elements. Moreover, it is apparent from the results that adjustments to the OSB power profile planning can potentially improve the reliability of the system for specific system sizing. It is also found that the OSB lifetime can be extended up to 2.5 times by increasing the capacity by 50 % and keeping the SoC close to around 50%.