Optimal coordination of DOCR in interconnected power systems

Directional over current relays (DOCRs) are the soul devices to protect any interconnected power system. Proper coordination of primary and adjacent protective relays along with minimum operating time is the desirable feature of these relays. To achieve this, selection of the optimum values of relay settings, mainly time dial setting (TDS) and plug setting (PS) is very much necessary. In this paper optimization of relay settings are done by Teaching Learning Based Optimization technique (TLBO), an efficient optimizer that mimics the classroom environment. Optimal coordination is verified by simulation in Western System Coordinating Council (WSCC) 9-bus system and compared with another popular optimization technique with satisfactory results. Results represent notable reduction in total relays' operating time and coordination time interval (CTI) in comparison with other techniques.