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This paper aims at characterizing and improving the metrological performances of current and voltage instrument transformers (CTs and VTs) in harmonic measurements in the power system. A theoretical analysis is carried out to demonstrate that, due to the iron core nonlinearity, CT and VT output signal is distorted even when the input signal is a pure sine wave. Starting from this analysis, a new method for CT and VT characterization and compensation is proposed. In a first step, they are characterized in sinusoidal conditions and the harmonic phasors of the distorted output are measured; in the second step, these phasors are used to compensate the harmonic phasors measured in normal operating conditions, which are typically distorted. The proposed characterization and compensation techniques are called SINusoidal characterization for DIstortion COMPensation (SINDICOMP). Several experimental tests, using high-accuracy calibration setups, have been performed to verify the proposed methods. The experimental results showed that the SINDICOMP technique assures a significant improvement of CT and VT metrological performances in harmonic measurements.

A novel measurement approach for power-flow analysis in medium-voltage (MV) networks, based on load power measurements at low-voltage level in each secondary substation (SS) and only one voltage measurement at the MV level at primary substation busbars, was proposed by the authors in previous works. In this paper, the method is improved to cover the case of temporary unavailability of load power measurements in some SSs. In particular, a new load power estimation method based on artificial neural networks (ANNs) is proposed. The method uses historical data to train the ANNs and the real-time available measurements to obtain the load estimations. The load-flow algorithm is applied with the estimated load powers, and the MV network state variables are obtained. The proposed method is validated for the real MV distribution network of the island of Ustica. The loads of selected SSs are estimated for two full days of different seasons. In comparison with previous works, satisfactory results are obtained in terms of uncertainty in the calculated power flows, thus suggesting the applicability of the proposed method for real-time monitoring of MV distribution networks.

The smart grid (SG) approach is based on a strong interaction between the network communication infrastructure and the power grid. Usually the management of the infrastructure is done by the distribution system operators (DSOs) that are worried about the increasing managing complexity due to the presence of increasing number of distributed energy resources and electrical vehicles. The use of software-defined networking (SDN) may simplify the network configuration and management for DSO, as highlighted from previous research works. The objective of this paper is to introduce and characterize an internet protocol (IP)-based communication architecture with specialized SDN bridges operating also over narrowband power line communication (PLC) to reach the last mile applications (e.g., smart meters and inverters). The feasibility of this approach depends on the communication performance of the supervisory level used to dynamically configure the SDN bridges. The characterization of this level is done using the following performance indicators: the round trip time (RTT), the packet loss (PL) ratio, and the actual IP throughput. The experimental results show the feasibility of the proposed architecture, since the limitations are given only by the physical implementation of the PLC modem. In detail, results of the case study show that the minimum RTT is on the order of 30 ms, the PL ratio is always less than 1.7% and the maximum throughput is of 95 Mbit/s, fully compatible with the requirements of the applications.

The increasing interest on the quality of the energy supplied and generated in distribution networks is raising the need of distributed power quality (PQ) measurements. To allow such capabilities with cost effective metering solutions, this paper wants to investigate the feasibility of using smart meters, already installed for energy billing, also for power quality monitoring. To this aim, an electronic board (based on STCOMET metrology device), already used in many energy meters of different countries, has been selected as case study platform. The manufacturer firmware of this board was essentially aimed at implementing energy meter metrics and power line communications functionalities. In this paper, new PQ functionalities were implemented and experimentally verified, taking into account the requirements of IEC 61000-4-30 for power quality measurements.

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. ? 2010-2012 IEEE.

This paper deals with the design, modeling and characterization of a new coupling system for medium voltage (MV) narrow band power line communications (NB-PLC). It exploits the capacitive divider of voltage detecting systems (VDSs) normally used to reveal the mains voltage presence, thus avoiding the use of dedicated MV couplers. The proposed coupling system was patented by the authors. In this paper, the modeling of the VDS capacitive divider is presented, using a proper characterization method. Moreover, the interface card design is described, based on simulation of the whole PLC transmission channel. Laboratory tests are also presented and discussed. More in detail, a frequency response analysis is performed to validate the developed model and the related simulations. Moreover, transmission tests with nPSK modems demonstrate that the proposed coupling system can be effective for narrowband modulated signal transmission. With respect to other tests presented in previous papers, in this paper the experimental characterization and validation was performed in an extended frequency range up to 200 kHz.