International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 02 Issue: 09 | Dec-2015 www.irjet.net p-ISSN: 2395-0072 © 2015, IRJET ISO 9001:2008 Certified Journal Page 273 WIDE AREA BACKUP PROTECTION SCHEME FOR POWER TRANSMISSION LINES USING PMU S.Karthick 1 , K.Lakshmi 2 1 PG student, Department of Electrical and Electronics engineering, K.S.Rangasamy College of Technology, Tiruchengode,Tamilnadu, india 2 Professor, Department of Electrical and Electronics Engineering, K.S.Rangasamy College of Technology, Tiruchengode,Tamilnadu, india ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract— This paper presents wide area backup protection scheme in power transmission lines. In this paper deals with PMU based wide area backup protection scheme for transmission lines developed to identify the faulted line by with PMUs. After a fault arises in the transmission network, zero and positive sequence currents entering the faulted backup protection zone highly increase, and faulted backup protection zone can be determined. To overcome these problems the optimization model is developed to identify the faulted line by using the wide area data of WAMS. Here linear least squares method is used to determine the faulted line as well as the fault location by voltage and current phasors of the Backup Protection Zone (BPZ) with limited measurement points. The proposed method is executed for IEEE-9 bus system using MATLAB/Simulink software. Keywords—Backup Protection Zone (BPZ), Phasor Measurement units (PMUs),Wide Area Measurement System (WAMS), IEEE 9-bus system. 1. INTRODUCTION The existing SCADA systems provide asynchronized measurements leading to inaccurate estimation of system states. Further, the slow data scan rate of about 2-10 seconds makes them inefficient to capture very short disturbances of the order of sub- seconds on the grid. These issues can be overcome by using the phasor measurement units, which utilize the global positioning system (GPS) receivers to accurately time-stamp each measurement. The capability of PMUs to measure 25 to 60 samples per second makes them suitable for analyzing the system under dynamic conditions. The deployment of PMU at each bus would facilitate direct measurement of all the states of the system. However, this is uneconomic and infeasible due to the higher installation cost of PMUs and limited communication facilities available. Thus, there is a need for strategic placement of PMUs across the power grid. A distance relay is designed to only operate for faults occurring between the relay location and the selected reach point, and remains stable for all faults outside this region or zone. The resistance of the fault arc takes the fault impedance outside the relay’s tripping characteristic and, hence, it does not detect this condition. Alternatively, it is only picked up either by zone 2 or zone 3 in which case tripping will be unacceptably delayed [6]. The distance relays are based on standalone decision, while each relay operates independently according to three different one of operation [2]. The mal-operation or fail-to trip of protection is determined as one of the origins to raise and propagate major power system disturbances. A vast majority of relay mal- operations is unwanted trips and have been shown to propagate major disturbances. Backup protections in fault clearance system have the task to operate only when the primary protection fails to operate or when the primary protection is temporarily out of service [3]-[5]. The recent complexity and enlargement of power systems makes it difficult to coordinate operation times and reaches among relays.