Salvatore Guaiana

A New Solution for Low-Voltage Distributed Generation Interface Protection System

In this paper, a new solution is proposed for the remote monitoring and control of distributed generators (DGs) and energy storage systems (ESSs) connected to low-voltage distribution networks. The proposed system fulfills the in-force standard requirements for the connection of DGs to the utility grid. Moreover, it allows implementing some enhanced functions for the remote control of inverters of DGs and ESSs, not only in terms of disconnection but also in terms of voltage regulation and power shuttering. The proposed solution is based on a new interface protection system and a dedicated secondary substation concentrator, which allows the communication between the distributed system operator and the inverters of DGs or ESSs. The proposed system was tested on field in the electrical network of the island of Ustica. An experimental characterization was carried out to find the best communication conditions, i.e., the frequency band with the lowest noise and attenuation, considering the signal amplitude and signal-to-noise ratio constraints, as well as the desired transmission data rate and transfer time.

A New Low Cost Coupling System for Power Line Communication on Medium Voltage Smart Grids

This paper proposes and verifies the performance of an innovative and low cost coupling system for power line communication (PLC) on medium voltage (MV) smart grids. The coupling system makes use of the capacitive divider of the voltage detecting systems (VDSs) to inject and receive the PLC signal. VDS are usually already installed in the MV switchboards of the major electrical manufacturer all over the world according to IEC 61243–5. VDS are used to detect the presence of the mains voltage to guarantee personnel safety. An interface circuit has been developed to be connected between the PLC transceiver and the VDS socket. In this way, the PLC signal can be coupled to the MV network without installing a dedicated MV coupler, thus avoiding the related costs of the coupler, the installation, and the temporary service interruption. The innovative device is able to couple digitally modulated narrowband PLC signals with modulation rate up to 19.2 kbit/s. In this paper, first a description of the proposed solution is reported. Second, its communication performance has been tested in laboratory. Finally, different tests have been carried out in two MV smart grid real installations under normal operation, i.e., in the presence of the mains voltage.

A Prototypal Architecture of a IEEE 21451 Network for Smart Grid Applications Based on Power Line Communications

This paper deals with the development of reliable measurement and communication devices and systems and their integration on a prototypal network architecture for smart grid applications, based on the use of narrowband power line communications (PLCs). The proposed solution is presented and discussed in the framework of the ISO/IEC/IEEE 21451 family of Standards. Currently, PLCs are not properly addressed by the aforesaid Standards; on the other hand, by including such issue, their guidelines could represent a common platform for the integration and interoperability of the proposed systems and devices. This would allow to exploit the benefits of the IEEE 21451 approach also for PLC-based smart grid applications, not only for the known functions of the smart metering, but also for sensing, automation, protection, and control functions and advanced system operation and management.

Narrowband power line communications for medium voltage Smart Grids

The aim of the paper is to show how narrowband power line communications (NB-PLCs) can be a valid solution for medium voltage grids. Advantages and drawbacks of this solution are analyzed, starting from some experimental communication results, which were carried out on the medium power system networks of the islands of Ustica and Favignana, in the presence of the net voltage. Furthermore, some communication architectures and hardware prototypes based on NB-PLCs are proposed for different smart grids applications.

An interface protection system with power line communication for distributed generators remote control

The aim of this work is to present a narrow band power line communication (NB-PLC) interface protection system (IPS) for distributed generators (DGs); it has been developed according to the current standard CEI 0-21 and the requirements for smart grid applications. For such applications, the new IPSs have to implement new intelligent functions such as remote monitoring and control of DGs and Energy Storage Systems (ESSs) inverters, not only in terms of disconnection but also of voltage regulation and power modulation by the utility control. The main feature of the developed IPS is the ability to interact with both the grid and the DGs and ESSs inverters. In fact, it can communicate with the Utility using a Power Line Communication (PLC) and with the DGs and ESSs inverter via Modbus over RS232 communication.

Experimental investigation on PLC signal crossing of power transformers

In this work the use of PLC in MV-LV networks is investigated, by means of experimental tests in the case of a two-ways MV/LV communication between two secondary substations. The two substations are connected by a MV overhead power line. Moreover each substation has a by-pass connection at MV bus-bars and a MV/LV power transformer. A ST7580 transceiver is used to inject the communication signal. The transceiver is embedded in a new interface device developed by the authors. In the paper the communication issues are introduced and some experimental tests are presented and discussed. Such tests have been carried out in the presence of voltage net, i.e. 24 kV, with the aim to verify the possibility of power transformer crossing.

Smart Interface Devices for Distributed Generation in Smart Grids: The Case of Islanding

With the increasing presence of distributed generators (DGs), the implementation of a smart sensors and actuators network in distribution grids has become crucial for different monitoring, management, and protection functionalities. For DGs monitoring and control, sensors and actuators are usually embedded in so-called interface devices (IDs) or interface protection systems. Existing IDs lack in communication interfaces both to the electrical energy distribution system operators (DSOs) and to the DGs inverter. In this framework, the authors have developed a new ID solution and a proper communication architecture, which allow implementing new smart functionalities based on the interaction with the DSO, such as remote control of DG power production or islanding detection. Regarding this last aspect, a new islanding algorithm is proposed, based on both local measurements and communications with DSO. The effectiveness of the proposed solution is shown on the real case study of Ustica Island’s distribution network.

A new low cost power line communication solution for smart grid monitoring and management

Modern smart grids require the improvement of measurement and communication infrastructures of distribution networks, at both medium voltage (MV) and low voltage (LV) levels. Distributed sensing and measurement systems are needed to provide all necessary data for grid monitoring, control and management, as well as for the implementation of a number of smart functionalities, such as remote control of distributed generators (DGs), real time analysis of power flows, automatic meter reading (AMR), demand side management (DSM), grid automation and so on [1]-[6]. Acquired network data include typical electrical network quantities and status variables (such as powers, voltages, currents, switches status, DGs power production, and remote commands) and also environmental and other parameters (temperatures, security or safety warning signals, etc.).

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.

Development of a coupling system for medium voltage power line communication in the CENELEC A frequency band

In this paper the performances of a new power line communication (PLC) coupling system for medium voltage (MV) smart grids are investigated in the CENELEC A frequency band (i.e. 3-95 kHz). The new coupling solution is based on the use of the capacitive divider of the voltage detecting system (VDS) as PLC coupler to the MV network. According to IEC 61243-5, VDS are worldwide used to reveal the presence of the mains voltage to ensure the safety of the operators. A proper interface circuit has been invented and patented to couple the PLC signal through the VDS. In this way no dedicated MV PLC coupler is required, thus avoiding the related costs of the coupler, of its installation, and those of the associated temporary service interruption. In this paper, a laboratory characterization of the developed coupling solution is presented in the only standardized band, CENELEC A, reserved for the Energy Utilities in Europe.