Single phase earth faults in high impedance grounded networks : characteristics, indication and location

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Hänninen, Seppo 2012-02-10T09:31:16Z 2012-02-10T09:31:16Z 2001-12-17
dc.identifier.isbn 951-38-5961-4
dc.identifier.issn 1455-0849
dc.description.abstract The subject of this thesis is the single phase earth fault in medium voltage distribution networks that are high impedance grounded. Networks are normally radially operated but partially meshed. First, the basic properties of high impedance grounded networks are discussed. Following this, the characteristics of earth faults in distribution networks are determined based on real case recordings. Exploiting these characteristics, new applications for earth fault indication and location are then developed. The characteristics discussed are the clearing of earth faults, arc extinction, arcing faults, fault resistances and transients. Arcing faults made up at least half of all the disturbances, and they were especially predominant in the unearthed network. In the case of arcing faults, typical fault durations are outlined, and the overvoltages measured in different systems are analysed. In the unearthed systems, the maximum currents that allowed for autoextinction were small. Transients appeared in nearly all fault occurrences that caused the action of the circuit breaker. Fault resistances fell into two major categories, one where the fault resistances were below a few hundred ohms and the other where they were of the order of thousands of ohms. Some faults can evolve gradually, for example faults caused by broken pin insulators, snow burden, downed conductor or tree contact. Using a novel application based on the neutral voltage and residual current analysis with the probabilistic method, it is possible to detect and locate resistive earth faults up to a resistance of 220 kΩ. The main results were also to develop new applications of the transient based differential equation, wavelet and neural network methods for fault distance estimation. The performance of the artificial neural network methods was comparable to that of the conventional algorithms. It was also shown that the neural network, trained by the harmonic components of the neutral voltage transients, is applicable for earth fault distance computation. The benefit of this method is that only one measurement per primary transformer is needed. Regarding only the earth faults with very low fault resistance, the mean error in absolute terms was about 1.0 km for neural network methods and about 2.0 km for the conventional algorithms in staged field tests. The restriction of neural network methods is the huge training process needed because so many different parameters affect the amplitude and frequency of the transient signal. For practical use the conventional methods based on the faulty line impedance calculation proved to be more promising. en
dc.format.extent 78, [61]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher VTT Technical Research Centre of Finland en
dc.publisher VTT fi
dc.relation.ispartofseries VTT publications en
dc.relation.ispartofseries 453 en
dc.relation.haspart Hänninen, S. & Lehtonen, M. 1998. Characteristics of earth faults in electrical distribution networks with high impedance earthing. EPSR (Electric Power Systems Research), Vol. 44, No. 3, pp. 155-161.
dc.relation.haspart Hänninen, S., Lehtonen, M. & Hakola, T. 2001. Earth faults and related disturbances in distribution networks. Proceedings of IEEE PES SM2001, Vancouver, Canada, July 15-19, 2001. CD-ROM 01CH37262C. 6 p.
dc.relation.haspart Hänninen, S. & Lehtonen, M. 1999. Method for detection and location of very high resistive earth faults. ETEP (European Transactions on Electrical Power) Vol. 9, No. 5, pp. 285-291.
dc.relation.haspart Hänninen, S., Lehtonen, M. & Pulkkinen, U. 2000. A probabilistic method for detection and location of very high resistive earth faults. EPSR (Electric Power Systems Research), Vol. 54, No. 3, pp. 199-206.
dc.relation.haspart Hänninen, S., Lehtonen, M., Hakola, T. & Rantanen, R. 1999. Comparison of wavelet and differential equation algorithms in earth fault distance computation. PSCC'99. 13th Power Systems Computations Conference, Trondheim, Norway, June 28-July 2, Proceedings Vol. 2. Pp. 801-807.
dc.relation.haspart Eberl, G., Hänninen, S., Lehtonen, M. & Schegner, P. 2000. Comparison of artificial neural networks and conventional algorithms in ground fault distance computation. Proceedings of IEEE PES WM2000, Singapore, January 23-27, 2000. CD-ROM 00CH37077C. 6 p.
dc.relation.haspart Hänninen, S. & Lehtonen, M. 2001. Earth fault distance computation with artificial neural network trained by neutral voltage transients. Proceedings of IEEE PES SM2001, Vancouver, Canada, July 15-19, 2001. CD-ROM 01CH37262C. 6 p.
dc.subject.other Electrical engineering en
dc.title Single phase earth faults in high impedance grounded networks : characteristics, indication and location en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Electrical and Communications Engineering en
dc.contributor.department Sähkö- ja tietoliikennetekniikan osasto fi
dc.subject.keyword power distribution en
dc.subject.keyword distribution networks en
dc.subject.keyword earth faults en
dc.subject.keyword detection en
dc.subject.keyword positioning en
dc.subject.keyword fault resistance en
dc.subject.keyword arching en
dc.subject.keyword neutral voltage en
dc.subject.keyword residual current en
dc.subject.keyword transients en
dc.identifier.urn urn:nbn:fi:tkk-001823
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en

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