Study of Overcurrent Relays Coordination Optimization based on Genetic Algorithms

One of the important protection relays in the electric power system is the overcurrent relay. In determining the value of relay settings In the relay setting process, formula calculation result can not be used directly, causing the process considered not optimal. Also, there are no tools for scanning protection in distribution subsystem. The research was made to optimize the calculation of overcurrent settings (ISET) and delay time (TMS). This research was made using MATLAB software by combining genetic algorithms and standards from IEC to calculate overcurrent relay setting values. To get optimal Iset and TMS values, data is needed including bay name, substation name, CT ratio, lowest current capacity at the corresponding time, local bus short circuit current, and characteristic curves. Coordination built on calculation uses link current level of each related local GI bus. After data is fulfilled, the user only needs to run the Genetic Algorithm script so that Iset and TMS values in related bays will be optimized with genetic algorithms. With this research, the protection engineer will easily obtain the value of his protection settings and also scanning protection in related subsystems to improve system reliability and availability of electrical energy distribution.