New Method for Discrimination of Transformers Internal Faults from Magnetizing Inrush Currents Using Wavelet Transform

Rahmati, Abouzar; Sanaye‐Pasand, M.

doi:10.1109/icpst.2008.4745190

Cited by 12 publications

(10 citation statements)

References 16 publications

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“…Finally, in order to minimize the error, it can be written as equation (16). Then, equation (17) is resulted and also equation (17) is derived from (16).…”

Section: Frequency Estimation (Prony Method)mentioning

confidence: 99%

“…However, a full data cycle is required for the related calculations and the method needs both current and voltage signals simultaneously. Moreover, [16] presents a wavelet based algorithm to inrush identification, but it does not use restraint principle. A morphological scheme for inrush identification in transformer protection is studied in [17].…”

Section: Introductionmentioning

confidence: 99%

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Differential protection improvement of power transformers using wavelet analysis of power system frequency

Abniki

Monsef

Nabavi-Razavi

et al. 2011

2011 16th International Conference on Intelligent System Applications to Power Systems

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This paper presents a new technique for inrush current detection of power transformers. The method is based on wavelet analysis of power system frequency which is estimated by Prony method. The Prony method is utilized to estimate power system frequency with three consecutive samples rapidly. After that, Daubechies wavelet family uses the estimated frequency to investigate the unbalanced conditions in power system. Meanwhile, a new time based criterion is introduced to determine internal fault currents from inrush currents by using the changes of estimated power system frequency. Extended simulations for various faults and inrush conditions demonstrate precise operation of the proposed algorithm also in CT saturation. Keywords -Power transformer protection, inrush current, internal fault, wavelet transform, frequency estimation, Prony method. I. INTRODUCTIONStability of transformer's protection scheme is one of the critical issues for power system operation performance [1]. One of the fast and reliable protection schemes for power transformer is based on differential current which is called differential protection. Unfortunately, this scheme maloperates in some cases like inrush condition or external fault, which leads to current transformer (CT) saturation. The phenomenon of transformer inrush current has been widely discussed in many papers. In 1904, Merz and Price developed the first approach for differential protection of transformers. The advantage of their proposed scheme was fast recognition and after that the technique has been extensively applied [2]. In order to stabilize the differential protection against maloperation in the event of external faults, the "differential current" tripping parameter is standardized to a stabilization parameter. As one of the other methods, wave shape based recognition methods are divided among those methods that are based on the identification of the separation of different current peaks [3,4]. Other methods for discriminating between internal fault currents and inrush currents are based on direct recognition of the differential current shape. A common well-known principle is discussed in [5]. Ref [6] discusses the length of the time intervals during which the differential current is near zero. Nevertheless, the length of the time interval of inrush currents is decreased in current transformer saturation condition. Some methods use DC offset or asymmetry in the differential current [7][8][9][10][11]. References [12, 13] present wavelet based method for discrimination between inrush currents and internal fault currents, but it does not work in all conditions. Moreover, some of the other methods extract second harmonic of inrush current, but second harmonic is significantly decreased due to the improvement of core steel in modern power transformers [14]. Meanwhile, a large second harmonic component can be introduced in internal fault of transformer in many cases. So, 2 nd harmonic based methods cannot be a final solution to this goal. Proposed method in [15] uses equival...

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“…Finally, in order to minimize the error, it can be written as equation (16). Then, equation (17) is resulted and also equation (17) is derived from (16).…”

Section: Frequency Estimation (Prony Method)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Differential protection improvement of power transformers using wavelet analysis of power system frequency

Abniki

Monsef

Nabavi-Razavi

et al. 2011

2011 16th International Conference on Intelligent System Applications to Power Systems

View full text Add to dashboard Cite

show abstract

“…Some methods [2][3][4][5] have been proposed to discriminate the magnetizing inrush current from the internal fault currents. Most of these algorithms are based on the harmonic contents of the inrush currents (mostly second harmonic), or specific pattern recognition of the inrush current waveform.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, different algorithms have been proposed to improve the operation of the DIFP relay. In general, one important key problem needs to be resolved by these efforts: how to immune the DIFP relay operation against the magnetizing inrush current and CT saturation condition.Some methods [2][3][4][5] have been proposed to discriminate the magnetizing inrush current from the internal fault currents. Most of these algorithms are based on the harmonic contents of the inrush currents (mostly second harmonic), or specific pattern recognition of the inrush current waveform.…”

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confidence: 99%

Protection of power transformer using multi criteria decision-making

Rahmati

Sanaye‐Pasand

2015

International Journal of Electrical Power & Energy Systems

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“…The wavelet analysis is one of the newly applied frequency analysis tools for processing signals with complex characteristics. Recently the wavelet analysis and wavelet transforms have emerged as a powerful tool for signal processing in power system applications [2,12,13]. The transient characteristics of wavelets can be employed to carry out accurate and effective analysis of signals with complex frequency-time structure.…”

Section: Introductionmentioning

confidence: 99%

A novel algorithm for discrimination between inrush current and internal faults in power transformer differential protection based on discrete wavelet transform

Eldin

Refaey

2011

Electric Power Systems Research

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New Method for Discrimination of Transformers Internal Faults from Magnetizing Inrush Currents Using Wavelet Transform

Cited by 12 publications

References 16 publications

Differential protection improvement of power transformers using wavelet analysis of power system frequency

Differential protection improvement of power transformers using wavelet analysis of power system frequency

Protection of power transformer using multi criteria decision-making

A novel algorithm for discrimination between inrush current and internal faults in power transformer differential protection based on discrete wavelet transform

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