An improved technique for power transformer protection using fuzzy logic protective relaying

Abstract

The three-phase power transformer in the transmission or distribution substations represents one of the essential devices on electric power networks. Losing this devise cause a disconnection of the power utility to a large number of electrical loads. The robust protection system must be designed to protect the device during abnormal operations. A complete protection system for a poly-phase power transformer for one of the Karbala transmission networks (East Karbala substation) is modeled and simulated, adopting a fuzzy logic protective relaying using MATLAB/SIMULINK environment. This study discusses fuzzy logic-based relaying for a power transformer safety, as well as internal faults that are clearly identified. Two principles of operation are used to protect the transformer; differential relay and overcurrent relay. The differential relay is proposed as the unit protection, while the overcurrent is backup protection. The proposed fuzzy logic controller (FLC) is used to detect abnormal operation; it is also modeled to organize the operation between unit and backup protection. The numerical results clarify that the proposed model can perform fast, rigorous, and authoritative protection for the transformer. Also, modeling of the protection mode decreases the complexity of designing various subsystem and combining them in one controller.