Adaptive Protection Scheme for Optimal Relay Coordination in Tboung Khmum Radial Distribution System Using an Adaptive Modified Firefly Algorithm

Relay coordination plays an essential role in power system protection, ensuring the safety and reliability of the operation of the electrical network. In the presence of distribution generators (DGs), directional overcurrent relays (DOCRs) are used to ensure the reliability and speed of relay operation and avoid malfunction in the primary relay and the backup during the contributed current injected from DGs when the fault occurs in the system. This paper presents an adaptive scheme for optimizing the DOCRs coordination in the radial distribution system with multiple DGs. An adaptive protection scheme is applied to determine the optimal protection coordination for different system configurations. An adaptive modified firefly algorithm (AMFA) is proposed to find the DOCR coordination in the distribution system by determining the optimal values of the plug setting (PS) and the time multiplier setting (TMS). In this study, the Tboung Khmum radial distribution system in Cambodia, with two DGs connected at the end of each line, is used as the case study. The proposed AMFA is tested under four different cases and compared with the conventional method. The results illustrate that AMFA can reduce the total operating time of DOCR coordination.