Publications

Energy Analysis of a Metro Train

For over a decade, Europe has focused on greening public transport, with modern railways playing a key role to reduce pollution and transport emissions because it is characterized by a relatively low ratio between energy consumption and transport capacity. However, DC railways waste a significant amount of energy regenerated with dynamic braking. Despite the evident importance of the presented topic, there is a lack of experimental knowledge in technical and scientific literature about the amount of energy and the power levels that are involved in the described mechanism though this is fundamental information for the design of the storage system. This paper presents some experimental results of an energy analysis of a metro train

Energy Recovering in DC Railway Systems

For over a decade, Europe has focused on greening public transport, with modern railwaysplaying a key role to reduce pollution and transport emissions because it is characterizedby a relatively low ratio between energy consumption and transport capacity. However,DC railways waste a significant amount of the energy regenerated with dynamic braking.The adoption of an energy storage system can greatly improve this situation by increasingenergy saving. This paper explores this issue starting from experimental data recordedduring the monitoring of a railway traction unit in commercial service on different tracks.The energy flows during braking in real conditions has been analyzed, quantifying theamount of energy that can be recovered by adopting an energy storage system placed onboard trains or in railway stations.

Traceability for AC Ripple Over DC Current

Direct current (dc) is experiencing a new renaissance. The consolidated high-voltage direct current (HVdc), together with new medium voltage direct current (MVdc), and low-voltage direct current (LVdc) are more and more present in research and development projects. One of the relevant topics, associated with the usage of dc, is the ac ripple that unavoidably accompanies the dc signals. The interest in the measurement of this quantity is linked with the determination of the performance of dc energy meters for billing purposes. The on-line power quality (PQ) analysis, the verification of the capabilities of the filtering systems, and the accurate determination of losses associated with the transmission, distribution, and conversion of the electric energy by dc systems require accurate determination of the ac ripple. National metrology institutes (NMIs) provide traceability only for pure ac or pure dc current signals. To guarantee a high-quality standard for such measurements, the article proposes a novel methodology, named ALFO, for the traceable calibration of measuring systems with signals composed by dc with superimposed ac ripple. The calibration setup is based on a decoupling transformer (DeT) which has been specifically designed by a numerical tool. A detailed analysis and quantification of the systematic errors affecting the measurement and of uncertainty budget have been performed. The setup can calibrate current measuring systems up to 100 A (dc) with ac ripple up to 1% of the dc in the frequency range 300 Hz–150 kHz. Preliminary evaluation of the standard uncertainty, performed at maximum 40 A dc and 1 A ac up to 250μA /A in the range of 300 Hz–150 kHz.

Estimation of Railway Line Impedance at Low Frequency UsingOnboard Measurements Only

Setup for the calibration of current measuring systems under DC signals affected by ripple