Reliability Analysis of HTS Cable Systems

In this study, a reliability model of a high-temperature superconducting (HTS) cable system is proposed. There are two versions of this HTS-system reliability model, depending on the scope of its application. As an independent system, there are three operating states in an HTS system, that is, a normal state, a postponable outage state, and an outage state. The probability and frequency of each state are calculated using the Markov model. However, when used as part of a distribution system, a derated state is added to the model because of the unique overcurrent behavior of the HTS cable system. The probability of this derated state depends on the condition of the HTS cable system. The proposed models are applied to an HTS cable project planned by the State Grid of China. The results illustrate the effectiveness of a backup refrigerator in the cooling system. The effects of a spare line in parallel with an HTS cable are quantitatively estimated with the model. The reliability of an HTS cable can be calculated using the proposed models if the required data are available.