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This article investigates the feasibility of using a simplified approach, based on the measurement of power ratio parameters, for harmonic emissions assessment at the point of common coupling (PCC). The proposed approach comes from the common concept of power factor correction and the definitions of the IEEE Std. 1459-2010, where line utilization and harmonic pollution levels are evaluated by means of ratios between the power quantities of the apparent power decomposition. In addition to the IEEE Std. 1459–2010 indicators, in this article, the behavior is studied of additional parameters that are conceptually similar to those defined by the IEEE Std. 1459-2010. The suitability of such parameters is discussed, for both single- and three-phase balanced/unbalanced cases, taking into account both their behavior in different scenarios and their effectiveness when the measurement uncertainty is taken into account. The study is supported by some simulation results that have been obtained on an IEEE benchmark power system, which allows reproducing linear and nonlinear load conditions, balanced and unbalanced operating conditions, and the presence of capacitors for power factor correction. [ABSTRACT FROM AUTHOR]

The monitoring and the management of smart grid require an advanced communication infrastructure. The time synchronization is among the most important services such an infrastructure should offer. Several solutions are available to disseminate the time information in a distributed system; for instance, most of the times a global positioning system (GPS) receiver is used to recover accurate time information. However, GPS receivers need a clear view of the sky. Other solutions, like the use of a network-based synchronization mechanism, require a dedicated communication infrastructure, which is not always feasible for economical reason. Thus, the use of the power grid itself to disseminate a time signal is extremely interesting. The aim of this article is to investigate the possibility to distribute a time signal over a medium voltage (MV) grid using a chirp-based modulation. The timing data are coded using IRIG-B time code. Such an approach does not require the installation of a dedicated infrastructure, and it is noninvasive, because the signal is transmitted on a different band with the respect to power line communication (PLC). The effectiveness of the approach has been experimentally evaluated on a test MV line available in a laboratory. Although the tested chirp-based symbol has a limited frequency bandwidth (80 kHz), the jitter in the identification of the start of frame is on the order of 7.5 $\mu \text{s}$ , fulfilling the requirements of the most smart grid applications. [ABSTRACT FROM AUTHOR]

This article presents an enhanced system for real-time power flow monitoring and control (PFMC) for microgrids integration in medium-voltage (MV) distribution networks. The developed solution includes both system architecture and the monitoring and control algorithms, and it has low implementation and installation costs. It is based on the use of hardware and software solutions previously proposed by the authors, i.e., a distributed measurement, a control and communication architecture, and a supervisory control and data acquisition (SCADA) software, which have been enhanced and integrated for the considered application. The SCADA implements a load flow (LF) algorithm for real-time power flows estimation in the MV network branches based only on the load powers measurements at low-voltage level. The system architecture includes new devices specifically designed for distributed generators (DGs) and energy storage systems (ESSs) remote control. The algorithm implemented on the developed PFMC system has been enhanced by including a real-time verification of LF results, which allows detecting devices' unavailability or malfunction occurrence. The PFMC has been implemented in the islanded scenario of the MV distribution network of Ustica Island (Mediterranean Sea) and it has been verified experimentally, in a measurement campaign of one year. In order to deal with different scenarios of DGs/ESSs presence in the microgrid, different operating conditions were reproduced during the measurement campaign, including the case of power flow inversion; such conditions have been obtained by means of an ad hoc developed on-field DG emulator which was remotely controlled by the SCADA system. [ABSTRACT FROM AUTHOR]

The monitoring and the management of smart grid require an advanced communication infrastructure. The time synchronization is among the most important services such an infrastructure should offer. Several solutions are available to disseminate the time information in a distributed system; for instance, most of the times a global positioning system (GPS) receiver is used to recover accurate time information. However, GPS receivers need a clear view of the sky. Other solutions, like the use of a network-based synchronization mechanism, require a dedicated communication infrastructure, which is not always feasible for economical reason. Thus, the use of the power grid itself to disseminate a time signal is extremely interesting. The aim of this article is to investigate the possibility to distribute a time signal over a medium voltage (MV) grid using a chirp-based modulation. The timing data are coded using IRIG-B time code. Such an approach does not require the installation of a dedicated infrastructure, and it is noninvasive, because the signal is transmitted on a different band with the respect to power line communication (PLC). The effectiveness of the approach has been experimentally evaluated on a test MV line available in a laboratory. Although the tested chirp-based symbol has a limited frequency bandwidth (80 kHz), the jitter in the identification of the start of frame is on the order of 7.5 $\mu \text{s}$ , fulfilling the requirements of the most smart grid applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

This paper presents a method for the detection of series arc faults in electrical circuits, which has been developed starting from an experimental characterization of the arc fault phenomenon and an arcing current study in several test conditions. Starting from this, the authors have found that is it possible to suitably detect arc faults by means of a high-resolution low-frequency harmonic analysis of current signal, based on chirp zeta transform, and a proper set of indicators. The proposed method effectiveness is shown by means of experimental tests, which were carried in both arcing and nonarcing conditions and in the presence of different loads, chosen according to the UL 1699 standard requirements. [ABSTRACT FROM PUBLISHER]

In this paper, a method to characterize the high-frequency (HF) behavior of six pack insulated gate bipolar transistors (IGBTs) power module (PM) is presented. The method is based on experimental measurements at the external pins of the device and it allows one to extract internal inductive and capacitive parasitic coupling without the knowledge of structural and physical parameters of the PM. The HF model of a six pack IGBTs PM has been developed, in the frequency range of 150 kHz–30 MHz, and it has been implemented in MATLAB environment. The method has been experimentally validated by comparing the frequency behavior of the PM with the simulated response. Moreover, the HF conducted disturbances, generated by the PM and measured in the dc link, have been compared with the simulation results verifying the proposed model. [ABSTRACT FROM AUTHOR]

This paper deals with the issue of measurement device placement for load flow analysis in medium-voltage (MV) distribution networks. The study is carried out using an innovative measurement algorithm for load flow analysis developed by the authors. It is based on low-voltage (LV) load power measurements applied on a backward/forward algorithm for the load flow resolution. The final aim is to identify the most suitable number and placement of the LV measurement points in order to limit the uncertainty on the power flow estimation to a target value. The proposed approach is based on the uncertainty evaluation of the estimated power flows; a sensitivity analysis is performed in order to assess the uncertainty contribution of each LV power measurement to the estimated power flow upstream of each MV feeder of the distribution network. The LV measurement device placement is presented and discussed in a real case study, i.e., the distribution network of the Ustica Island. [ABSTRACT FROM AUTHOR]

This paper proposes a novel measurement procedure for load flow analysis in medium voltage (MV) smart grids. The new approach is based on power measurements at low voltage (LV) side of MV/LV distribution substations. Such measurements are carried out by means of power quality analyzers. If compared with the load flow methods based on measurements at the MV side, the proposed approach has a lower cost and it offers an equally reliable measurement system. The proposed algorithm takes the basic concept of the current summation backward/forward method; some modifications are introduced to use LV load powers measurements. To this aim, the MV/LV power transformer is properly modeled and taken into account in the algorithm. The proposed approach is validated by means of both simulations and experimental measurements; the test system is the MV distribution grid of Ustica Island, Italy. First, the proposed algorithm is compared with the MATLAB/Simulink load flow tool, which is based on the traditional Newton-Raphson method. Second, a comparison is carried out between the proposed method and the measurement data collected in the actual MV network of Ustica. Such comparison takes into account the uncertainties of both proposed method, and experimental active and reactive MV power measurements. [ABSTRACT FROM PUBLISHER]