International journal of Engineering, Business and Management (IJEBM) [Vol-1, Issue-2, July-Aug, 2017] AI Publications ISSN: 2456-7817 www.aipublications.com Page | 1 Analysis of Distance Protection for EHV Transmission Lines Using Artificial Neural Network Ezema C.N 1 , Iloh J.P.I 2 , Obi P.I. 3 1, 2 Department of Electrical /Electronic Engineering, Chukwuemeka Odumegwu Ojukwu University, Anambra State, Nigeria 3 Department of Electrical/Electronic Engineering, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria. Abstract— The main goal of this work is to locate fault in an electric power system with the optimal practically achievable accuracy. The method employed in this work makes use of phase voltages and phase currents (scaled with respect to their pre-fault values) as inputs to the neural networks. Typical faults such as single line-ground, line- line, double line-ground and three phase faults were considered and separate Artificial Neural Networks (ANNs) have been proposed for each of these faults. Since Back Propagation neural networks are very efficient when a sufficiently large training data set is available, it has been chosen for all the three steps in the fault location process namely fault detection, classification and fault location. The average and the maximum error percentages are in tolerable ranges and hence the network’s performance is considered satisfactory. It can be seen that there is a steady decrease in the gradient and also that the number of validation fails did not exceed 1 during the entire process which indicates smooth and efficient training because the validation and the test phases reached the Mean Square Error performance (MSE) goal at the same time approximately. Keywords— Double-Circuit Line Fault, Ground Fault Location, Line – Line Faults, Fault Location Algorithms. I. INTRODUCTION High voltage transmission lines cover long distances, hundreds of kilometers, particularly when the line passes through hilly and harsh terrains. When a fault occurs on these transmission lines it is extremely difficult to patrol the line from tower to tower to identify the faulty spot. Accurate identification and location of faults does not only save time but also saves power. Power system operators need accurate information to enable speedy deployment of men and machinery to the fault’s location in order to rectify the fault thereby saving lot of time and resources. Using software applications, communication systems such as Supervisory Control and Data Acquisition (SCADA) and Power Line Carrier Communication (PLCC) hardware system can be designed for fault location. Data from SCADA such as oscillographs, relays and the sequence of events are used for fault location. Now available latest technology GPS can be used to locate a fault on long high voltage transmission lines. Self monitoring hardware devices are configured at foundation sites for both conditions by inserting the information of a fault location (GPS) into Geographical information system computer. 1.1 Existing Double-Circuit Line Fault Location Algorithms Diverse fault location algorithms designed for double- circuit lines have been developed in the past few decades and will be henceforth reviewed. In the phasor-based fault location category, some methods utilize only one-terminal data to locate a fault. Akke & Thorp (2016) assume that the angles of a fault current and the fault current distribution from the load end are equal. They propose an algorithm that utilizes one-terminal voltage and current data. Because of their approximation the accuracy of their fault location is affected by the fault resistance and the asymmetrical arrangement of the transmission lines (Anderson, 2015). Eriksson et al. (2016) employed phase voltages and currents from the near end of the faulted line, and a zero-sequence current from the near end of the healthy line as input signals. To fully compensate the error introduced by the fault resistance (or the impact of the remote in-feed), source impedance values are required. Kawady and Stenzel (2014) used a modal transformation to decouple the initially coupled transmission lines. Their method utilizes as input voltage and current phasors from a locally installed relay. Compared with Eriksson et al. (2016), this algorithm does not need source impedances. It