NB PLC and Software Defined Networking for Smart Grid Applications

During the last years, the installation of Distributed Energy Resources (DERs) and the expected diffusion of Electrical Vehicles (EVs), is increasing the complexity of the distribution grid, making the management of the grid operated by Distribution System Operators (DSOs) more difficult. The Smart Grid approach tries to provide a response to these troubles, by means of a strong interaction between the power grid and Information and Communication Technology (ICT) infrastructures. The drawback of this approach is an increase in the management effort of the ICT infrastructures, for which the DSO are not prepared. Software Defined Networking (SDN) is an approach developed to manage complex ICT infrastructures of datacenters, and its main target is to simplify the network configuration and management. The Smart Grid could benefit from the use of an SDN approach for the management of the communication infrastructure, as highlighted from previous research works. The target of this paper is to present a real case application of the SDN technology for the management of DERs over the distribution grid. The communication between electrical devices placed along the power grid and the secondary substations is provided by using Modbus RTU protocol over narrowband power line communication (NB-PLC). The preliminary characterization highlights that the Round Trip Time (RTT) on NB-PLC segment is affected by the used frequency band and by the modulation scheme. In the worst case (i.e., transmission at 72 kHz and a BPSK coded modulation, for a total data rate of 4.9 kb/s), the RTT is in the order of 140 ms, compatible with the requirements of the application.