A Voltage Calibration Chain for Meters Used in Measurements of EV Inductive Power Charging

The inductive charging of electric vehicles requires specific measurement and calibration systems. In fact, the measurement of power on board involves DC signals, which are superimposed to a significant AC ripple up to or over 150 kHz, depending on the type of charging system. A calibration method that makes use of a phantom power, based on two independent but synchronized circuits, is considered, simulating the charging voltage and current. This paper describes in detail a solution in the realization of the voltage calibration chain, based on the use of a DC voltage calibrator, an injector and a voltage divider.Comment: 2 pages, Conference on Precision Electromagnetic Measurements (CPEM 2018), Paris

A Method for the Measurement of Digitizers’ Absolute Phase Error

A lot of engineering applications, from telecommunications to power systems, require accurate measurement of phase angles. Some of them, like synchrophasor measurement and calibration of instrument transformers with digital output, in order to reach high phase measurement accuracy, require the knowledge of phase error of digitizers. Therefore, in this paper a method for the measurement of digitizers’ absolute phase errors is proposed. It adopts a sinewave and two square waves, that are the digitizer sample clock and a phase reference signal. Combining the measurements of the relative phase differences between the adopted signals it is possible to accurately evaluate the absolute phase error of a digitize

Understanding the impact of demand shocks on the container port industry

The Covid-19 pandemic has severely impacted the world economy, generating an unprecedented shock that pushed carriers to adapt to the collapse of demand. Most of the related adaptation actions (e.g., blank sailings) appear as temporary initiatives being insufficient to reach a long run equilibrium. Moreover, while carriers managed to adjust their own supplied capacity to the ongoing crisis, the port sector has been greatly impacted by the fall in transport demand, not being able to counteract the demand shortages as effectively as the carriers. Against this backdrop, the paper introduces a model for assessing the effects of demand shocks (e.g., due to the pandemic) on the integration strategies of carriers. We focus on the possible initiatives that demand shocks may trigger on the horizontal and vertical integration among the actors of the shipping industry. In doing so, the present study provides useful insights for better understanding potential future market modifications and their impact on social welfare. Using non-cooperative games, profit-maximising strategies, in case of such integrations, are compared in order to study how carriers and terminal operators might react to demand shocks in the medium and long run

Impact of DC Transient Disturbances on Harmonic Performance of Voltage Transformers for AC Railway Applications

This paper analyzes the impact of typical DC transient events occurring in railway grids on the frequency performance of instrument transformers (ITs) installed onboard trains and in AC substations for power quality (PQ) applications. PQ monitoring in railway systems is an issue of great interest because it plays a key role in the improvement of energy efficiency. The measurement chain for the PQ measurements, at 15 kV at 16.7 Hz and 25 kV at 50/60 Hz, commonly includes ITs to scale the voltage to levels fitting the input of the measurement units. Nevertheless, the behavior of ITs in the presence of PQ phenomena represents an open issue from a normative point of view, even for those installed in conventional AC power supply systems. In this context, the paper presents a possible definition of DC transient disturbances test waveforms, a measurement procedure, and a setup to assess the impact of these disturbances on the harmonic performances of ITs for railway systems. Preliminary experimental tests carried out on two commercial ITs under wide ranges of variation for the amplitude and the time duration of DC disturbances show that, in some cases, the error introduced in harmonic measurements can exceed 100%

FPGA-based real time compensation method for medium voltage transducers

open5noSince the increase of the distributed power connected to the medium voltage networks, a capillary monitoring of the power quality becomes essential. This entails the spread of transducers with suitable frequency bandwidths, as required by the relevant standards. The paper describes a real time compensation method for the extension of the frequency bandwidth of medium voltage dividers whose performances do not allow to perform measurements over a wide frequency range. This approach will contribute to keep the costs of this innovation lowopenCrotti, Gabriella; Gallo, Daniele; Giordano, Domenico; Landi, Carmine; Inrim, Mario Luiso2 1Crotti, Gabriella; Gallo, Daniele; Giordano, Domenico; Landi, Carmine; Inrim, Mario Luiso2

Calibration of voltage and current transducers for dc railway systems

To establish a single European railway area, the European Commission requires, by 2019, that energy billings shall be computed on the actual energy consumed. So, in the near future, all the trains shall be equipped with an energy measurement system, whose measurement accuracy should be assessed and periodically reverified, as required by EN 50463-2. As for every energy and power measuring system, the voltage and current transducers play a crucial role as their accuracy could determine the performance level of the entire measurement chain. To answer to this emerging need, this paper presents a calibration system allowing the accurate testing of dc voltage and current transducers, up to 6 kV and 300 A and up to 10 kHz. It is able to reproduce all the tests prescribed by EN 50463-2, but in order to characterize the transducers in actual operating conditions, a series of additional tests can also be performed using synthetic complex waveforms or even signals acquired on-board trains. The expanded uncertainty (level of confidence 95%) of the calibration system is 43 mu extV /V and 24 mu extA /A at dc and 520 mu extV /V and 820 mu extA /A at 10 kHz. Moreover, the calibration of two commercial voltage and current transducers, currently installed in the trains of an Italian operator, is presented

Characterised measuring system for PQ measurements on the MV grid

Peer Reviewe

Calibration System for DC Power/Energy Measurement chain in Railway applications

In order to guarantee the European interoperability of rolling stock, the European Union (EU) established that all the trains shall be equipped with an Energy Measurement Function (EMF) for billing purposes. The measurement accuracy of such devices should be assessed and periodically re-verified, as required by EN 50462-2. This paper describes a setup for the calibration of combined voltage and current transducers and EMFs for on-board Direct Current (DC) train installation. The reference system is able to generate an arbitrary DC phantom power up to 6 MW with voltage up to 5 kV and a current up to 1.2 kA. Furthermore, in order to perform tests as close as possible to real operating conditions, the system allows performing dynamic tests, reproducing waveforms obtained in real measurement campaigns. The computed uncertainty for steady state tests is 0.025%, whereas the target uncertainty for dynamic tests is 0.1%. The generation system can also be applied for on-board reverification of EMF

Il ruolo della logistics social responsibility per la sostenibilit\ue0 nella movimentazione delle merci

Negli ultimi anni ha assunto particolare interesse il concetto di logistics social responsibility, inteso come un insieme di pratiche di sostenibilit\ue0 che perseguono lo scopo principale di ricercare soluzioni efficienti nell\u2019organizzazione della supply chain e, nello stesso tempo, disegnare strategie per una mobilit\ue0 delle merci a basso impatto ambientale e orientata al riutilizzo dei materiali, secondo i paradigmi dell\u2019economia circolare. In questo contributo, dopo aver delineato il recente adattamento della corporate social responsibility ai settori della logistica, evidenziando la prevalente tassonomia delle annesse pratiche manageriali, viene analizzato un filone di letteratura prospettico, che aggiunge al tema della sostenibilit\ue0 logistica quelli del packaging e dello stoccaggio sostenibili. Questa rilettura critica di una letteratura settoriale, che evolve in parallelo alle declinazioni della mobilit\ue0 sostenibile nel trasporto delle merci, persegue il duplice obiettivo di mappare le direzioni concettuali della logistics social responsibility e, in particolare, di prospettare filoni di ricerca connessi alla supply chain e di orientare possibili interventi di policy dei decision-makers pubblici e privati