894 IEEE TRANSACTIONS ON SMART GRID, VOL. 6, NO. 2, MARCH 2015 Detection and Location of High Impedance Faults in Multiconductor Overhead Distribution Lines Using Power Line Communication Devices Apostolos N. Milioudis, Student Member, IEEE, Georgios T. Andreou, Member, IEEE, and Dimitris P. Labridis, Senior Member, IEEE Abstract—An effective power system protection scheme has to be able to detect and locate all occurring faults corresponding to low and high impedance values. The latter category poses the greatest challenge for the protection schemes due to the low values of the related fault current. This paper extends pre- vious work by the authors on the subject, aiming to achieve detection and location of high impedance faults (HIFs) in mul- ticonductor overhead distribution networks utilizing power line communication (PLC) devices. Fault detection is proposed to be performed by a PLC device installed at the starting point of the monitored line and by using differences to the values of metrics related to input impedance at frequencies utilized by narrowband systems. Moreover, fault location can be derived by a response to impulse injection procedure utilized by all installed PLC devices along the line. The method is evaluated and validated in various simulation test cases concerning its ability to effectively detect and locate HIFs. Index Terms—Fault location, high impedance fault (HIF) detection, multiconductor distribution lines, power distribu- tion faults, power line communications (PLCs), power system protection, smart grids. I. I NTRODUCTION P OWER SYSTEM protection is a critical issue for both operational and safety reasons. An efficient protection scheme has to be able to ensure that the power system operates adequately, and protects the equipment as well as the public from hazardous overvoltages. For most occurring faults, over- current relays installed for distribution system protection can detect and cut off the supply to the feeder containing the fault. Nevertheless, the possibility of a fault occurrence that will cause a slight increase to the line current, cause of its high impedance, and thus not be detectable by the conventional pro- tection schemes has to be taken into account. This will result to the design of an enhanced protection scheme which will be able to detect and isolate both low and high impedance faults (HIFs), improving thus the protection capability of the power system. Manuscript received December 14, 2013; revised May 24, 2014 and September 16, 2014; accepted October 20, 2014. Date of publica- tion November 12, 2014; date of current version February 16, 2015. Paper no. TSG-00914-2013. The authors are with the Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece (e-mail: amilioud@auth.gr; gandreou@auth.gr; labridis@auth.gr). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TSG.2014.2365855 The problem of HIF detection has been documented for the first time by Aucoin and Russell [1] who proposed the usage of the measured current harmonic content from 2 to 10 kHz. Since then the specific subject has drawn the attention of the scientific community and rigorous studies have been con- ducted toward the design of an efficient protection scheme. Lee and Osborn [2] proposed the monitoring of the zero sequence current component with respect to the value of the phase current adopting the context used in ground overcur- rent relays. Moreover, artificial intelligence methods have been used such as neural networks [3], [4], fuzzy logic [5], and decision trees [6]. Additionally, Zamora et al. [7], [8] pro- posed the injection of low frequency test signals, while the utilization of wavelet transformation has also been adopted in [9]–[11]. The problem with most proposed solutions is the need for respective investments in order to incorporate them in the grid. However, the upcoming evolution of traditional power systems to smart grids may come as a solution, introducing smart grid equipment that may also be used to provide pro- tection functionality. Most of the new capabilities of the smart grid require data communication and several technologies appear as candidates for that purpose [12]–[15]. Among them power line communications (PLC) systems, while provid- ing narrowband [16], [17] and broadband solutions [18]–[20], also exhibit a techno-economic advantage, as they do not require further investments for network installation by uti- lizing the electrical grid as communication backbone. In order to improve its potential, PLC technology faces the challenge to enable additional functionality, besides data communication [21]–[25]. Within this context PLC systems could be also used to improve the power system protection schemes. Milioudis et al. [26]–[29] have already investigated the possibility of utilizing PLC systems for fault detection and location in medium voltage (MV), regarding them as single conductor systems. Thus, the proposed protection scheme is the extension of that previously published work. While using the same basic conceptual schemes, monitoring differences in input impedance values at specific frequencies for fault detec- tion and implementing response to impulse injection procedure for fault location, the initial simplification of single phase sys- tems is no longer adopted. The protection scheme is extended to be able to take into account multiconductor configurations, 1949-3053 c  2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.