IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 11, Issue 3 Ver. IV (May. – Jun. 2016), PP 07-15 www.iosrjournals.org DOI: 10.9790/1676-1103040715 www.iosrjournals.org 7 | Page Transmission Line Fault Detection Using Synchrophasor Miss. Bharti R Phirke 1 , Prof. D. S. Chavan 2 1,2 Electrical EngineeringBharatiVidyapeeth Deemed University College of EngineeringPune, India Abstract:The accuracy in fault detection and location is always a challenge for a power system engineer. The current differential protection has the highest reliability among all types of protection scheme, but it is not being used for transmission line protection because of certain problems such as CT ratio mismatch, pilot wire length, tap changing transformer etc. This paper describes the details about the synchrophasor technology which uses the GPS based time synchronization having the accuracy of the order of 1μs. This paper explored the flexibility of the synchrophasor technology based current differential protection in Matlabsimulink and presented the results for all types of faults with different fault resistance, inception angle, and fault location, and it is observed the current differential protection using synchrophasor technology has almost the 100% reliability. Keywords:current differential protection, charging current compensation,synchrophasor. I. Introduction Most of limitations of current differential protection can be overcome by digital current differential protection based n microcomputer by using digital communication link. For digital differential protection, to make differential comparison, not the current waveforms varying with time, to satisfy the requirement of current differentialprinciple. The sample of protected line from all terminals can be time aligned in synchronization. This kind of protection can be implemented using this technique, is known as synchronization Technology and GPS are given. This is completely new technology. By using this technology for current differential protection for transmission line having ideally no limit fits length. II. New Theory Of Current Differential Protection Capacitive current [1] could be using several new theories. Several ways to overcome capacitive current have been suggested .Current differentialprotection will be able to overcome the capacitive current as a way to protect UHV transmission line system. But these new theories have to be tested and implemented as in electric power system. The relay protection reliability requirements are strict and precise. Therefore a simple and feasible way to improve current differential protection which can compensate steady capacitive current and transient without increasing the computation consumption, samplingrate, computation consumption and telecommunication channel. Time domain compensation algorithm [2], for performing the differential equation for transmission line of π equivalent circuit has been implemented recently. This algorithm is supposed to solve the capacitive current problem for steady and transient distributed capacitive current. III. Differential Protection Scheme For Transmission Line Using Synchrophasors 3.1 The System to Be Simulated Specifications Generator- 600MVA, 22KV, 60Hz, H= 4.4MW-S/MVA, Xd= 1.81pu, Xd‟= 0.γpu, Xd”= 0.βγpu, Tdo‟=8s, Tdo”=0.0γs, Xq= 1.76pu, Xq”= 0.β5pu, Tqo”=0.0γpu,