# Simulation of a Narrowband Power Line Communications System over Medium Voltage
## 1 Introduction  
The Smart Grid (SG) is a power network which can intelligently integrate/incorporate the actions of generators, distributors and consumers of energy. Employing information and communication technologies (ICT), the SG aims at delivering electrical power in a sustainable, economic and secure way [1]. In addition to enhancing the efficiency, reliability and safety of power delivery, the SG will also: (i) increase the penetration and enhance the smooth integration of distributed renewable electric power generation, (ii) implement the practically real-time participation of energy producers and consumers in the energy market, and (iii) push forward the use of electrical vehicles. All of these enhanced applications and services necessitate ICT solutions customized to transmission and distribution networks [2, 3]. The benefits expected by Distribution System Operators (DSOs) and end users from the SG are operational, economic, environmental and security specific. As a result, many DSOs intend to deploy last mile communication infrastructure to monitor crucial network operations and exchange information with critical nodes of the transmission and the distribution grid (e.g., generators, substations, large consumers). Specifically, DSOs have the options of using: (i) Power Line Communications (PLC), to move digital information through the grid via the very power lines used for the transmission and distribution of electric power; or (ii) wireless communication technologies, to communicate with substations and implement services primarily related to remote metering. The SG communications (SGC) architecture comprises two layers, the power system layer, responsible for the safety and reliability of the distribution grid, and the communications layer, intended for the exchange of information between nodes of the power grid. Broadband PLC (BB-PLC), also referred to as Broadband over Power Lines (BPL), is a technology appropriate for last mile access. As verified by _in situ_ measurements from various pilot PLC installations, BB-PLC enables broadband transmission in the 1-100 MHz frequency range at raw data rates exceeding 200 Mbps [4]. Though both the low voltage (LV) and the 1-33 kV MV grid can be employed for BB-PLC transmission, the latter is subjected to less adverse transmission conditions, making feasible the deployment of BB-PLC networks over the MV grid at acceptable QoS levels. Combined with the recently released IEEE P1901 standard [5] and the ubiquitous presence of the MV grid, BB-PLC technology seems attractive for SG applications destined for the MV grid [6]. Narrowband PLC (NB-PLC) refers to low data rate communications utilizing the frequency band either below 148.5 kHz in Europe (following the CENELEC standard: 3-148.5 kHz) or below 450 kHz in the USA and several Asian countries. NB-PLC technology utilizes the power grid to implement low rate network services related to switching and monitoring. However, both PLC options face a harsh transmission environment characterized by a time-varying transfer function and, sometimes, non-white additive noise of high power spectral density (PSD) [7]. The propagation environment faced by the two PLC options varies. In particular, the attenuation in the relatively narrow NB-PLC frequency range is quite low and exhibits smaller variations. On the other hand, in the significantly broader BB-PLC frequency range, the attenuation exhibits a non-monotonic behavior in a much broader range of values. In both cases, signal transmission is impeded, necessitating the use of orthogonal frequency division multiplexing (OFDM) techniques. On the other hand, though the additive white Gaussian noise (AWGN) assumption is valid for the noise encountered in BB-PLC, it is not valid for NB-PLC, where the relevant noise exhibits a non-white and non-Gaussian behavior, a feature that must be taken into account in NB-PLC transmission analysis. BB-PLC operates over a significantly broader frequency range, thus being capable of supporting high data rate SG applications.