An Equivalent Circuit for the Evaluation of Cross-Country Fault Currents in Medium Voltage (MV) Distribution Networks

Fabio Massimo Gatta, Alberto Geri, Stefano Lauria and Marco Maccioni
Additional contact information
Fabio Massimo Gatta: Department of Astronautics, Electric and Energy Engineering, “Sapienza” University of Rome, Rome 00184, Italy
Alberto Geri: Department of Astronautics, Electric and Energy Engineering, “Sapienza” University of Rome, Rome 00184, Italy
Stefano Lauria: Department of Astronautics, Electric and Energy Engineering, “Sapienza” University of Rome, Rome 00184, Italy
Marco Maccioni: Department of Astronautics, Electric and Energy Engineering, “Sapienza” University of Rome, Rome 00184, Italy

Energies, 2018, vol. 11, issue 8, 1-12

Abstract: A Cross-Country Fault (CCF) is the simultaneous occurrence of a couple of Line-to-Ground Faults (LGFs), affecting different phases of same feeder or of two distinct ones, at different fault locations. CCFs are not uncommon in medium voltage (MV) public distribution networks operated with ungrounded or high-impedance neutral: despite the relatively small value of LGF current that is typical of such networks, CCF currents can be comparable to those that are found in Phase-To-Phase Faults, if the affected feeder(s) consists of cables. This occurs because the faulted cables’ sheaths/screens provide a continuous, relatively low-impedance metallic return path to the fault currents. An accurate evaluation is in order, since the resulting current magnitudes can overheat sheaths/screens, endangering cable joints and other plastic sheaths. Such evaluation, however, requires the modeling of the whole MV network in the phase domain, simulating cable screens and their connections to the primary and secondary substation earth electrodes by suitable computer programs, such as ATP (which is the acronym for alternative transient program) or EMTP (the acronym for electromagnetic transient program), with substantial input data being involved. This paper presents a simplified yet accurate circuit model of the faulted MV network, taking into account the CCF currents’ return path (cable sheaths/screens, ground conductors, and earthing resistances of secondary substations). The proposed CCF model can be implemented in a general-purpose simulation program, and it yields accurate fault currents estimates: for a 20 kV network case study, the comparison with accurate ATP simulations evidences mismatches mostly smaller than 2%, and never exceeding 5%.

Keywords: cross country fault; simplified circuit model; mixed cable-overhead MV distribution network (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.mdpi.com/1996-1073/11/8/1929/pdf (application/pdf)
https://www.mdpi.com/1996-1073/11/8/1929/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:11:y:2018:i:8:p:1929-:d:159732

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().