XIX IMEKO World Congress Fundamental and Applied Metrology September 6-11, 2009, Lisbon, Portugal ON THE MODEL OF MV POWER LINE COMMUNICATION SYSTEM IN THE CASE OF LINE TO LINE TRANSMISSION A. Cataliotti 1 , G. Tinè 2 1 Department of Electrical, Electronic and Telecommunication Engineering, University of Palermo Viale delle Scienze, 90128 Palermo, Italy, email: acataliotti@ieee.org 2 ISSIA (Institute on Intelligent Systems for the Automation) - CNR (Research National Council) Via Dante, 12 - 90141 Palermo, Italy, email: giovanni.tine@cnr.it Abstract - In this paper a complete model of Medium Voltage (MV) power system for PLC communications, in the frequency domain, is presented. A simple and friendly Simulink ® software is used to develop the model. A distributed parameters MV cables model in line-line configuration is considered. Also the signal coupling networks with the generation and receiving systems are included. The performances of the complete PLC communication system are evaluated introducing the attenuation constant computed as ratio between the received and transmitted voltage signals. The signal losses produced by the complete system in the CENELEC frequency band and for different cable lengths are also considered. Keywords: medium voltage, power line communication, attenuation constant 1. INTRODUCTION In recent years, near to the huge development of the power line communication (PLC) for low voltage (LV) system the application of PLC to medium voltage (MV) power networks has had an increasing interest [1-2]. The network management optimization, the monitoring of the system and the operational services are the most important PLC applications for the MV networks [3]. In Europe, the available frequency intervals for communication systems on LV and MV power networks are settled by CENELEC EN 50065-1 [4]. The standard specifies five different bandwidths from 3 kHz to 148 kHz. In Northern America and in Japan the regulation is more permissive because it allows one to use frequencies up to 525 kHz, i.e. up to the AM broadcast threshold [5]. A further reference for PLC systems is the IEEE standard 643 – 2004 [6]. In the case of cable lines, two configurations are mainly used, line-ground and line-line configuration. In the line-ground configuration the signal is injected between a phase and cable shield. The shield is normally connected to the ground at the ends of the line. In the line-line configuration, the signal is injected between two phases of a three-phase power system, or between the phase and the neutral conductor of a single-phase power system. In both cases the signal can be injected by capacitive couplers or inductive couplers [6]. In literature, different studies have been presented on the behaviour both of high voltage (HV) and MV overhead lines and on LV cables at high frequency. On the other hand, there are few studies on the behaviour of MV cable lines [7-8]. The models proposed are mainly based on Bergeron’s model, used also in this work [1-9]. In previous works the authors have presented a model to simulate the signal transmission through a MV cables in the line-ground and line-line configurations [10][11][12]. In this paper a complete model of MV power system for PLC communications, in the frequency domain, is presented in nthe case of a line to line configuration. The model requires the knowledge of the per unit length parameters of the transmission lines [10][11][12]. Moreover the coupling system for the signal injection, the signal generator and the signal receiver are considered. In this paper, firstly the system under study is presented. Secondly, a description of the complete model with all the single components are reported. Finally, the simulation results in term of attenuation constant are illustrated by comparing the results for different line lengths. 2. SYSTEM UNDER STUDY The system under study is composed by three unipolar MV shielded cables type RG7H1R with aluminum core and 185 mm 2 cross-section. The transmission system is based on line-line configuration in which the signal is injected in the cores of two cables and the external conductor of each cable are connected together to ground. The signal are injected and received by two commercial coupling networks (CN) whereas the signal generator and the receiver are connected by two isolation transformers. In Fig.1 a simplified schematic representation of the system under study is sketched. 892 ISBN 978-963-88410-0-1 © 2009 IMEKO