DocumentCode :
1257925
Title :
Bayesian Selectivity Technique for Earth Fault Protection in Medium-Voltage Networks
Author :
Elkalashy, Nagy I. ; Elhaffar, Abdelsalam M. ; Kawady, Tamer A. ; Tarhuni, Naser G. ; Lehtonen, Matti
Author_Institution :
Sch. of Sci. & Technol., Dept. of Electr. Eng., Aalto Univ., Espoo, Finland
Volume :
25
Issue :
4
fYear :
2010
Firstpage :
2234
Lastpage :
2245
Abstract :
In Nordic countries, distribution networks are unearthed or compensated. Earth faults, particularly in compensated networks, provide fault currents that are low compared to the load currents. Identification of the faulty feeder is therefore difficult. A preliminary description of discrete wavelet transform (DWT)-Bayesian selectivity technique was introduced in reference 1 to identify the faulty feeder. It was dependent on a conditional probabilistic method applied to transient features extracted by using the DWT. However, a practical setting for this technique has not yet been presented. Furthermore, its sensitivity is limited to 1.5-k fault resistances, and is further reduced to 170 when considering current transformer and network noise. In this paper, the ratio between the absolute sums of the DWT detail level from each feeder is used as an input to the conditional probability approach, providing an enhanced selectivity decision. This input contributes to discriminating the faulty feeder during high resistance faults. The relay setting is introduced as a function of the number of feeders and their characteristic impedances, as the proposed algorithm is dependent on the discharge´s initial transients. The performance is evaluated taking into account current-transformer and network noises. A digital implementation is experimentally verified by using two digital signal processing boards.
Keywords :
Bayes methods; discrete wavelet transforms; earthing; power distribution faults; probability; Bayesian selectivity technique; Earth fault protection; conditional probabilistic method; digital signal processing boards; discrete wavelet transform; distribution networks; faulty feeder; load currents; medium-voltage networks; resistance 1.5 kohm; resistance 170 ohm; Bayesian methods; Circuit faults; Current transformers; Digital signal processing; Discrete wavelet transforms; Earth; Fault currents; Fault detection; Fault diagnosis; Feature extraction; Medium voltage; Noise reduction; Protection; Resistance; Transient analysis; Compensated medium-voltage (MV) networks; conditional probability; digital signal processing (DSP); discrete wavelet transform (DWT); earth fault detection; initial transients;
fLanguage :
English
Journal_Title :
Power Delivery, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-8977
Type :
jour
DOI :
10.1109/TPWRD.2010.2053562
Filename :
5524100
Link To Document :
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