Improvement of Critical Clearing Time by Combination of SFCL and SCES Using Critical Trajectory Method

The importance of stability in electric power systems and the concept of Critical Clearing Time (CCT) as the time required for the protection system to clear faults and maintain system stability. The paper explores the use of Superconducting Fault Current Limiters (SFCL) and Super Capacitor Energy Storage (SCES) to improve system stability and increase CCT values. The critical trajectory method is employed to calculate CCT values, and the Time Domain Simulation (TDS) method is used for comparison. The IEEE 3machine 9-bus system is used as a case study. This method offers improved computational accuracy and speed compared to other approaches. The simulation results demonstrate that the enhancement of CCT values through the utilization of SFCL and SCES is influenced by factors such as the placement location, size of the devices, and the specific fault points within the system. The simulation results show that the combination of SFCL and SCES can increase CCT values, indicating improved system stability. The optimal configuration is determined to be SFCL installed on lines 1-4 and SCES installed on the critical generator bus. The average increase in CCT values is 6.31% for this configuration. This application allows for an extended duration during which the protection system can isolate the fault. Finally, it can preserve system stability after fault periods and upgrade the relative system transient stability level. The proposed combination utilization strategy is simulated and modified using Matlab R2022a.