Reliability assessment of All-DC electrical collection system for offshore wind farms: a hierarchical framework from component to system level

Abstract The harsh operating conditions of deep offshore wind farm (OWF) significantly reduce the reliability of electrical collection system (ECS). Traditional assessment methods for conventional AC-ECS often rely on reliability parameters that are unsuitable for the challenging wind conditions encountered in deep offshore environments. Moreover, the lack of empirical data from operational DC-ECS introduces substantial uncertainty into the reliability evaluations. To address these issues, this paper proposes a hierarchical assessment framework, encompassing component, device and system levels. For the key components of DC-ECS that are impacted by harsh wind conditions, the framework begins with multi-time scale lifespan prediction of power modules at the component level. These predictions are then utilized in device-level reliability calculations for critical equipment. Finally, the sequential Markov Chain Monte Carlo (MCMC) method is employed to assess the reliability of ECS under different topologies. A 300 MW wind farm is used as a case study to validate the feasibility of the proposed method, and the influence of individual equipment reliability and other factors on the overall system reliability is analyzed.