Transformer differential protection with fuzzy logic based inrush stabilization

Second harmonic restraint is still commonly used to discriminate fault current and transformer inrush conditions. Such approach, however, has some disadvantages and limitations. Therefore various other criteria signals for power transformer inrush discrimination have been analysed. The paper presents a new multi-criteria stabilization algorithm that employs fuzzy reasoning technique for better discrimination of inrush conditions. The developed protection algorithm has been tested with EMTP-ATP generated signals as well as real-world data, proving to be reliable and much more sensitive than standard algorithms with traditional criteria and crisp settings.