Superconducting cables can be used as an alternative to replace the conventional ac cables in a power system. Because of the characteristics of superconducting cables, their installation in a power system can influence the fault current levels and patterns. These changes in fault current levels and patterns can further have an impact on power system protection. Therefore, in order to prevent resulting problems, there is an increasing need to analyze the impact of a superconducting cable on the power system and determine its impedance under fault conditions. This paper presents a systematic impedance selection method for a superconducting cable under fault conditions, based on the evaluation results of the impact of superconducting cables on power system protection. Numerical simulations are carried out to demonstrate the effectiveness of the proposed method.