Abstract
Directional current relays are one of the most common relays that are used in the protection of transmission and distribution lines. They provide reliable protection for the transmission lines. However, increasing proliferation of distributed energy sources may violate established relay coordination. This is caused by changes in fault current levels at the fault points, and thus coordination time interval of the relays are violated. This basically means that primary and backup relays do not operate in coordination with each other. Thus, it is vital to optimizing the relay settings in accordance with changing fault current levels. This paper proposes agent-based adaptive coordination mechanism of relay settings acquired by heuristic optimization algorithms in case of 19 bus IEEE test feeder with the presence of distributed generations.