Showing papers by "Matti Lehtonen published in 2001"
18 Jun 2001
TL;DR: In this article, a fully automatic computer model, called the FI-model, for distribution network fault location, fault isolation and supply restoration is presented, which works as an integrated part of substation SCADA and medium voltage distribution network automation systems, including protective relays and AM/FM/GIS.
Abstract: In this paper, a fully automatic computer model, called the FI-model, for distribution network fault location, fault isolation and supply restoration is presented. The model works as an integrated part of substation SCADA and medium voltage distribution network automation systems, including protective relays and AM/FM/GIS (automated mapping, facilities management and geographic information system).
22 citations
18 Jun 2001
TL;DR: In this paper, the frequency and cost of voltage sags for customers of five Finnish distribution companies were evaluated and it was shown that voltage sag is a relevant power quality issue having economic significance.
Abstract: Frequency and cost of voltage sags for customers of five Finnish distribution companies were evaluated. For voltage sag frequency calculations the method of fault positions was applied. Only sags caused by short circuit faults in medium voltage distribution networks were considered. Sag frequency below considered 50% magnitude showed quite low numbers. However the cost related to this sag magnitude revealed that voltage sags are a relevant power quality issue having economic significance.
20 citations
01 Jan 2001
TL;DR: Evaluation of the applicability of SDS for this particular data transmission purpose, measuring the performance of the TETRA system and developing the data structures of transmitted data blocks are put to.
Abstract: Traditionally, proprietary communication solutions, specially tailored for SCADA applications, have been used for the communication between the network control center (NCC) and remote terminal units (RTUs) of distribution automation systems. However, due to the emerging development of open digital radio transmission protocols it may be possible to change the communication towards open solutions. This paper describes a pilot system where TETRA Short Data Service (SDS) has been used for data transmission between a NCC of Helsinki Energy and four 0.4 kV secondary substations. Main emphasize is put to the evaluation of the applicability of SDS for this particular data transmission purpose, measuring the performance of the TETRA system and developing the data structures of transmitted data blocks.
14 citations
15 Jul 2001
TL;DR: In this article, a novel application of the neural network approach for transient based earth fault location in 20 kV radial power distribution networks is presented, where neural networks trained by the harmonic content of neutral voltage transients are applied to fault distance computation in the case of very low fault resistance.
Abstract: A novel application of the neural network approach for transient based earth fault location in 20 kV radial power distribution networks is presented. The items discussed are earth fault transients, signal pre-processing, ANN training and the performance of the proposed distance estimation method. The distribution networks considered are either unearthed or resonant earthed. Neural networks trained by the harmonic content of neutral voltage transients were found to be applicable to fault distance computation in the case of very low fault resistance. The mean error in fault location was about 1 km in the field tests using staged faults, which were recorded in real power systems.
13 citations
15 Jul 2001
TL;DR: In this article, the characteristics of the earth faults and related disturbances, recorded in medium voltage overhead distribution networks during the years 1998-1999, were analyzed, and the use of subharmonic oscillation and harmonic distortion was investigated, as a means of anticipating of faults.
Abstract: This paper describes the characteristics of the earth faults and related disturbances, recorded in medium voltage overhead distribution networks during the years 1998-1999. Altogether 316 real cases were analyzed. The use of subharmonic oscillation and harmonic distortion was investigated, as a means of anticipating of faults. Arcing faults made up at least half of all the disturbances, and were especially predominant in the unearthed network. Fault resistances reached their minimum values near the beginning of the disturbances. The maximum currents that allowed for autoextinction in the unearthed network were comparatively small.
13 citations
Patent•
19 Sep 2001
TL;DR: In this paper, a method and a system for detecting wire break in a three-phase (R, S, T) electrical network comprising at least one feeder (2) going out from a supply point (1), wherein values (IR, IS and IT) of currents of phases of the feeder or quantities corresponding thereto are monitored and it is detected that a wire break (F) occurs at the feeders if, during a predetermined time, the current value of one phase drops more than a predetermined limit value and the phase angle between the current values increases more than
Abstract: of EP1134865A method and a system for detecting a wire break in a three-phase (R, S, T) electrical network comprising at least one feeder (2) going out from a supply point (1), wherein values (IR, IS and IT) of currents of phases of the feeder or quantities corresponding thereto are monitored and it is detected that a wire break (F) occurs at the feeder if, during a predetermined time, the current value of one phase drops more than a predetermined limit value and the phase angle between the current values increases more than a predetermined limit value.
1 citations