Filter Transients onboard DC Rolling Stock and Exploitation for the Estimate of the Line Impedance

Mariscotti, Andrea; Giordano, D.; Femine, Antonio Delle; Signorino, Davide

doi:10.1109/i2mtc43012.2020.9128903

Cited by 8 publications

(7 citation statements)

References 32 publications

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“…A filter charging procedure is often used, using a limiting resistor that is then bypassed when the filter has reached a sufficient voltage level, meaning that capacitors are adequately charged. When connecting then to the current collection system, inrush is much reduced, although transients cannot be excluded, characterized by a rapid low-energy arc, as shown in [122].…”

Section: Inrush Current and Short-circuit Currentmentioning

confidence: 99%

Power Quality Phenomena, Standards, and Proposed Metrics for DC Grids

Mariscotti

2021

Energies

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This work addresses the problem of power quality (PQ) metrics (or indexes) suitable for DC grids, encompassing low and medium voltage applications, including electric transports, all-electric ships and aircrafts, electric vehicles, distributed generation and microgrids, modern data centers, etc. The two main pillars on which such PQ indexes are discussed and built are: (i) the physical justification, so the electric phenomena affecting DC grids and components (PV panels, fuel cells, capacitors, batteries, etc.), causing, e.g., stress of materials, aging, distortion, grid instability; and (ii) the existing standardization framework, pointing out desirable coverage and extension, similarity with AC grids standards, but also inconsistencies. For the first point, each phenomenon is discussed with quantitative conclusions on relevant thresholds: in many cases some percentage of distortion (ripple) is acceptable (stress on capacitors and storage, impact on fuel cells, and PV panels), whereas in other cases, much higher levels may be tolerated (interference to protection and monitoring devices). Standards are reviewed for indications not only of low-order harmonics and voltage fluctuations typical of old DC grid schemes, but also for high-frequency noise, including thus supraharmonics and common-mode disturbance, and filling the gap with the electromagnetic compatibility domain. However, phenomena typical of EMC and electrical safety (such as various types of overvoltages and fast transients) are excluded. Suitable PQ indexes are then reviewed, suggesting integrations and modifications, to cover the relevant phenomena and technological progress, and to better follow the normative exigencies: ripple is considered in time and frequency domain, in particular with a band limited implementation; for transients and pulsed loads, more traditional indexes based on area, energy, and half duration are confronted with indexes evaluating the power trajectory and its derivative.

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Section: Inrush Current and Short-circuit Currentmentioning

confidence: 99%

Power Quality Phenomena, Standards, and Proposed Metrics for DC Grids

Mariscotti

2021

Energies

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“…An ideal step change of the network voltage is exploited there to evaluate the network impedance, by measuring the re change of absorbed current in the load (assuming that load conditions do not vary during the network transient). Since the network voltage is not under control and switching a lumped load in and out is not trivial (with several issues related to the cost, electrical safety, rating and certification), an effective implementation needs to be identified [41]. Railway systems are rich in power supply transients that could be exploited to this aim, such as pantograph arcs [42][43][44] and switching of auxiliary loads and onboard devices [41].…”

Section: Indicators Requiring Additional Information On the Network A...mentioning

confidence: 99%

“…Since the network voltage is not under control and switching a lumped load in and out is not trivial (with several issues related to the cost, electrical safety, rating and certification), an effective implementation needs to be identified [41]. Railway systems are rich in power supply transients that could be exploited to this aim, such as pantograph arcs [42][43][44] and switching of auxiliary loads and onboard devices [41]. Impedance identification has been attempted for DC systems in a well-known configuration (onboard filter charging) for which the network equivalent circuit can be separated, but it is not readily extendable to AC railways, since the exploited transient is peculiar to a specific operation on DC networks.…”

Section: Indicators Requiring Additional Information On the Network A...mentioning

confidence: 99%

Metrology and Measurement Systems

MARISCOTTI¹

2020

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Electrified railways are an example of AC single phase distribution networks. A non-negligible amount of active and nonactive power may be related to harmonics, especially for distorted highly-loaded systems. The paper considers the relevance of the harmonic power terms in order to identify distortion sources in a single-point perspective, in line with the approach of EN 50463 for the quantification of the power and energy consumption. Some single-point Harmonic Producer Indicators (HPI) based on harmonic active power direction and nonactive distortion power terms are reviewed and evaluated using pantograph voltage and current measured during several hours of runs in two European AC railways (operated at 16.7 and 50 Hz). The HPI based on active power shows to be consistent and provides detailed information of rolling stock characteristic components under variable operating conditions; those based on nonactive distortion power are global indexes and hardly can operate with complex harmonic patterns in variable operating conditions.

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“…using a dc supply) undergo more intense arcing due to two factors: the supply is a dc voltage of significant amplitude (between 600 V and 3000 Vdc nominal), and current intensity can be an order of magnitude larger than ac railways. DC arcs in electrified transports have been characterized in the literature in terms of voltage-current relationship [1][3][4], typical waveforms and their spectra [5][6], and interaction with the traction line impedance and locomotive filter [2][7], exploiting them also for network impedance estimate [8].…”

Section: Introductionmentioning

confidence: 99%

How Pantograph Electric Arcs affect Energy Efficiency in DC Railway Vehicles

Mariscotti¹,

Giordano²,

Femine³

et al. 2020

2020 IEEE Vehicle Power and Propulsion Conference (VPPC)

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In DC electrified railways pantograph electric arcs represent not only a disturbance, but the step change of the pantograph voltage affects power losses directly and indirectly. The available line voltage is reduced if the train is in traction condition, the arc itself is characterized by ohmic power losses, and the triggered oscillating transient responses are characterized by a net power loss. In addition, if arc occurs during braking the arc voltage suddenly increases the pantograph voltage and may interfere with the dissipative braking chopper, reducing the recovered energy. This work presents the model and analysis these phenomena with the support of experimental results related to results for arcs measured on a 3 kV dc line in traction and braking conditions.

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Filter Transients onboard DC Rolling Stock and Exploitation for the Estimate of the Line Impedance

Cited by 8 publications

References 32 publications

Power Quality Phenomena, Standards, and Proposed Metrics for DC Grids

Power Quality Phenomena, Standards, and Proposed Metrics for DC Grids

Metrology and Measurement Systems

How Pantograph Electric Arcs affect Energy Efficiency in DC Railway Vehicles

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