Investigation on Fault Characteristics and Intelligent Diagnosis of a DC Superconducting Fault Current Limiter

The fault characteristics of superconducting fault current limiter (SFCL) are dynamic and nonlinear, which makes it difficult to recognize the failure state accurately. In this paper, the fault characteristics of a DCSFCL were investigated and an intelligent diagnostic method was proposed. We present mathematical formulations and a simulation model with COMSOL for transient analysis of DC power systems. The model consists of non-inductive superconducting coils, liquid nitrogen vessel. The value variation regularities of temperature, pressure and liquid level under different fault states were studied. In addition, kriging interpolation method was applied to solve convergence problem during thermal calculating. The correlations between characteristic parameters and operating status were analyzed. Framework for fault diagnosis of SFCL based on fault tree model was established and identification of the fault is carried out by comparison of obtained operating parameters with preset values. The results show that the fault type was determined by fault tree analysis. Moreover, the seriousness of fault is affected by the fault characteristic quantities, which provides an early warning of faults and benefit the condition-based maintenance.