JEE_V10_N3_RP3 J. Uday Bhaskar G. Ravi Kumar S.S. Tulasi Ram Journal on Electrical Engineering 2230 – 7176 10 3 18 29 Multi-Terminal Transmission, UPFC, Wavelet, Fault Index, Threshold Value, Fault Impedance, Fuzzy Inference System The difficulties in obtaining the Right-of-Way have led to the development of multi-terminal transmission systems and these transmission systems are more vulnerable to faults and required to be cleared immediately as soon as they do occur for minimizing the power system disturbances and for efficient transmission. This paper aims in the systematic approach for fault detection, classification, faulty terminal identification, and fault location estimation of a four-terminal transmission system compensated with Unified Power Flow Controller (UPFC) based on frequency domain approach employing wavelet multi resolution analysis with the variations in fault inception angle, fault distance, and fault impedance by extracting the fault indices of current signals of all the three phases at all terminals. These fault indices were then compared with threshold value to detect and classify the faults and also identify the faulty terminal. The fault indices were used as inputs to the Fuzzy Inference System (FIS) for approximate fault location estimation from the respective terminals. Bior 1.5 wavelet has been chosen as mother wavelet as it has given the accurate results when compared with other members of wavelet family. The entire simulation was carried out in MATLAB environment within 110 km, 400 KV four-terminal transmission system, and the classification and location algorithms can be used as effective tools for real time digital relaying purpose as it has taken less than half cycle to detect the faults. January - March 2017 Copyright © 2017 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=13411