An improved transformer differential relay

Mathews, C. A.

doi:10.1109/ee.1954.6438882

Cited by 24 publications

(14 citation statements)

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“…However, even for normal operating conditions, the RIVs are not always equal to the turns ratios because e1, e2, and e3 are instantaneous values and thus pass through zero. Therefore, the detectors described by Equations (5)- (7) are used to detect a fault instead of Equation (4). The detectors evaluate the percent difference between the two estimated induced voltages.…”

Section: Three-winding Single-phase Transformermentioning

confidence: 99%

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Induced Voltages Ratio-Based Algorithm for Fault Detection, and Faulted Phase and Winding Identification of a Three-Winding Power Transformer

et al. 2014

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This paper proposes an algorithm for fault detection, faulted phase and winding identification of a three-winding power transformer based on the induced voltages in the electrical power system. The ratio of the induced voltages of the primary-secondary, primary-tertiary and secondary-tertiary windings is the same as the corresponding turns ratio during normal operating conditions, magnetic inrush, and over-excitation. It differs from the turns ratio during an internal fault. For a single phase and a three-phase power transformer with wye-connected windings, the induced voltages of each pair of windings are estimated. For a three-phase power transformer with delta-connected windings, the induced voltage differences are estimated to use the line currents, because the delta winding currents are practically unavailable. Six detectors are suggested for fault detection. An additional three detectors and a rule for faulted phase and winding identification are presented as well. The proposed algorithm can not only detect an internal fault, but also identify the faulted phase and winding of a three-winding power transformer. The various test results with Electromagnetic Transients Program (EMTP)-generated data show that the proposed algorithm successfully discriminates internal faults from normal operating OPEN ACCESSEnergies 2014, 7 6032 conditions including magnetic inrush and over-excitation. This paper concludes by implementing the algorithm into a prototype relay based on a digital signal processor.

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Section: Three-winding Single-phase Transformermentioning

confidence: 99%

“…The transformer differential relays with harmonic based restraining or blocking signal [3][4][5][6] ensure stability during magnetizing inrush and over-excitation, but may reduce the sensitivity for internal faults. In addition, the method causes an operating time delay of a relay because of the restraining or blocking signal.…”

Section: Introductionmentioning

confidence: 99%

Induced Voltages Ratio-Based Algorithm for Fault Detection, and Faulted Phase and Winding Identification of a Three-Winding Power Transformer

et al. 2014

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“…The common technique utilized to prevent mal-operation of the differential protection during the energization of a power transformer is the level of harmonic components. The magnetizing inrush current includes high levels of the second harmonic component, which is used as a discriminative feature in conventional protective schemes [1,2].…”

mentioning

confidence: 99%

Control of unusual mal-operation of three-phase power transformer differential protection due to ultra saturation phenomenon based on Clarke׳s Transform and Discrete Wavelet Transform

Noshad

Ghanavati

Ahmadzadeh

et al. 2015

Renewable and Sustainable Energy Reviews

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“…Hayward [2] and Mathews [3] used all of the harmonics to restrain the differential relay for a transformer. Sharp and Glassburn [4] introduced the idea of harmonic blocking using the second harmonic.…”

Section: Introductionmentioning

confidence: 99%

“…Current-derived restraining or blocking methods are based on the harmonic contents in the operating currents [2][3][4][5] or wave shape identification [6,7]. Hayward [2] and Mathews [3] used all of the harmonics to restrain the differential relay for a transformer.…”

Section: Introductionmentioning

confidence: 99%

Saturation Detection-Based Blocking Scheme for Transformer Differential Protection

Lee

Won

et al. 2014

Energies

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This paper describes a current differential relay for transformer protection that operates in conjunction with a core saturation detection-based blocking algorithm. The differential current for the magnetic inrush or over-excitation has a point of inflection at the start and end of each saturation period of the transformer core. At these instants, discontinuities arise in the first-difference function of the differential current. The second-and third-difference functions convert the points of inflection into pulses, the magnitudes of which are large enough to detect core saturation. The blocking signal is activated if the third-difference of the differential current is larger than the threshold and is maintained for one cycle. In addition, a method to discriminate between transformer saturation and current transformer (CT) saturation is included. The performance of the proposed blocking scheme was compared with that of a conventional harmonic blocking method. The test results OPEN ACCESSEnergies 2014, 7 4572 indicate that the proposed scheme successfully discriminates internal faults even with CT saturation from the magnetic inrush, over-excitation, and external faults with CT saturation, and can significantly reduce the operating time delay of the relay.

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An improved transformer differential relay

Cited by 24 publications

References 0 publications

Induced Voltages Ratio-Based Algorithm for Fault Detection, and Faulted Phase and Winding Identification of a Three-Winding Power Transformer

Induced Voltages Ratio-Based Algorithm for Fault Detection, and Faulted Phase and Winding Identification of a Three-Winding Power Transformer

Control of unusual mal-operation of three-phase power transformer differential protection due to ultra saturation phenomenon based on Clarke׳s Transform and Discrete Wavelet Transform

Saturation Detection-Based Blocking Scheme for Transformer Differential Protection

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