Power transformer protection using fuzzy logic based controller

Abstract

The Power Transformer is one of the most expensive and important electrical equipment of a Power Transmission System, the loss of this equipment through catastrophic failure can be very costly. To avoid this, methods and systems for monitoring and protecting of Power Transformers in service are being developed. Since many mal-operation cases of transformer differential protection are caused by inrush current problems and thus, the rapid discrimination of inrush current from internal fault is most essential to avoid the inadvertent operation of the protective relay. Therefore, measures must be taken to ensure that the Power transformer differential relay operates precisely to differentiate between fault and non-fault conditions to ensure service reliability. This differential relay must restrain from tripping during magnetizing inrush and rapidly operate the tripping during internal faults. This paper presents a new relaying algorithm to enhance the fault detection sensitivities of conventional techniques by using fuzzy logic approach of MATLAB/Simulink. The proposed fuzzy-based relaying relies on the principle of harmoniccurrent restraint, where the magnetizing-inrush current is characterized by large second harmonic contents that are not noticeably present in fault currents