This paper presents a feasibility study on how to implement power quality (PQ) metrics in a low-cost smart metering platform. The study is aimed at verifying the possibility of implementing PQ monitoring in distribution networks without replacing existing smart metering devices or adding new modules for PQ measurements, thus zeroing the installation costs. To this aim, an electronic board, currently used for remote energy metering, was chosen as a case study, specifically the STCOMET platform. Starting from the specifications of this device, the possibility of implementing power quality metrics is investigated in order to verify if compliance with standard requirements for PQ instruments can be obtained. Issues related to device features constraints are discussed; possible solutions and correction algorithms are presented and experimentally verified for different PQ metrics with a particular focus on harmonic analysis. The feasibility study takes into account both the use of on-board voltage and current transducers for low voltage applications and also the impact of external instrument transformers on measurement results.

The paper 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 IEEE Std. 1459-2010, where line utilization and harmonic pollution levels are evaluated by means of ratios between power quantities of the apparent power decomposition. In addition to IEEE Std. 1459-2010 indicators, in this paper the behavior is studied of additional parameters, which are conceptually similar to those defined by IEEE Std. 1459-2010. The suitability of such parameters is discussed, for both single-phase and three-phase balanced/unbalanced case, 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 a 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.

In this paper, a new approach to modeling the hysteresis phenomenon of the open circuit voltage (OCV) of lithium-ion batteries and estimating the battery state of charge (SoC) is presented. A characterization procedure is proposed to identify the battery model parameters, in particular, those related to the hysteresis phenomenon and the transition between charging and discharging conditions. A linearization method is used to obtain a suitable trade-off between the model accuracy and a low computational cost, in order to allow the implementation of SoC estimation on common hardware platforms. The proposed characterization procedure and the model effectiveness for SoC estimation are experimentally verified using a real grid-connected storage system. A mixed algorithm is adopted for SoC estimation, which takes into account both the traditional Coulomb counting method and the developed model. The experimental comparison with the traditional approach and the obtained results show the feasibility of the proposed approach for accurate SoC estimation, even in the presence of low-accuracy measurement transducers.

Power line communication is one of the most today used technologies, for both automatic meter reading and many other smart grid applications. In this framework, a characterization of electrical network in PLC frequency range is needed in terms of impedance measurement and received signal level. This can allow choosing the most suitable and less noisy frequency ranges for PLC transmission. Usually, these characterization measurements are performed with dedicated instrumentation and in the absence of mains voltage. This paper wants to propose an alternative solution, which allows these kinds of measurement to be performed using electronic boards currently used as on-field applications such as smart meters. To this aim, an innovative measurement tool is proposed, which does not need a specific characterization signal to be injected, because it uses the preamble of a generic PLC transmission. Moreover, the impedance calculation is performed using a FFT analysis, which does not require high computational capabilities. These features allowed the proposed tool to be implemented using a G3-PLC transceiver, embedded in many commercial smart meters, and low-cost additional hardware. The paper shows how the proposed system correctly measures the PLC impedance on CENELEC A, B and FCC frequency ranges.

This paper proposes a virtual tool for load flow analysis in energy distribution systems of micro-grids. The solution is based on a low-cost measurement architecture, which entails low-voltage power measurements in each secondary substation and a voltage measurement at the beginning of the medium voltage (MV) feeder. The proposed virtual tool periodically queries these instruments to acquire the measurements. Then, it implements a backward–forward load flow algorithm, to evaluate the power flow in each branch and the voltage at each node. The virtual tool performances are validated using power measurements acquired at the beginning of each MV feeder. The uncertainties on each calculated quantity are also evaluated starting from the uncertainties due to the used measurement instruments. Moreover, the influence of the line parameter uncertainties on the evaluated quantities is also considered. The validated tool is useful for the online analysis of power flows and also for planning purposes, as it allows verifying the influence of future distributed generator power injection. In fact, the tool is able to off-line perform the load flow calculation in differently distributed generation scenarios. The micro-grid of Favignana Island was used as a case study to test the developed virtual tool.