Decreasing Distribution Generation Effects on Grid Short Circuit Level Using Superconducting Fault Current Limiter Through Updating Relays Set-Points

Power system protection at transmission and distribution levels based on overcurrent relays is essential based on their properties such as detection, stability, high speed, backup and error correction accuracy. Since distributed generation sources are connected to the power grid, they not only increase the short circuit level of the grid, but also disrupt the set point of main and backup relays, which will interrupt the healthy areas of the grid. In order to maintain the safety and stability of the network and to avoid increasing the power rating of the existing equipment, Superconducting Fault Current Limiter (SFCL) devices are utilized to significantly reduce the short circuit current at its primary cycles. However using of SFCLs, may lead to inadequate relay performance and lack of short circuit current detection. In order to solve the above problems, this paper presents a SFCL model with resistive structure and coupling inductance, while increasing the fault impedance path and reducing short circuit current, optimally. Then shielding synchronization between main relays and their near and far back-ups are achieved. Finally proposed objective function is minimized using the improved particle swarm optimization algorithm and three case studies will be performed. The simulation results represent the superiority of the proposed method in resolving the error and eliminating disturbance between the relays at the shortest possible time.