A new technique to classify transient events in power transformer differential protection using S-transform

Sendilkumar, S; Mathur, B. L.; Henry, Joseph

doi:10.1109/icpws.2009.5442730

Cited by 14 publications

(14 citation statements)

References 19 publications

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“…The generalised S-transform can be derived from the original S-transform by replacing the Gaussian window with a generalised window, as follows [27] S (4) where, p denotes a set of parameters that governs the shape of the window. S-transform windows must satisfy the following equation…”

Section: Introductionmentioning

confidence: 99%

“…Generally, DWT-based methods are easily influenced in a noisy environment [23]. Therefore S-transform-based methods that are influenced less by noise, have been proposed in [23][24][25][26][27] for discriminating inrush current and internal and external faults. However, in the abovementioned works, CTs error and ratio mismatch, external faults considering CT saturation, turn to turn and turn to earth faults have not been taken into account and the terminal model of the transformer has been used.…”

Section: Introductionmentioning

confidence: 99%

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Hyperbolic S-transform-based method for classification of external faults, incipient faults, inrush currents and internal faults in power transformers

Ashrafian

Rostami

Gharehpetian

2012

IET Gener. Transm. Distrib.

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In this study, a hyperbolic S-transform-based method is proposed to discriminate most important transient fault currents of transformers. First, the proposed method discriminates external faults from other disturbances. Then, the S-transform is applied to differential currents. An index is suggested by using absolute deviations of the S-matrix of differential currents to discriminate internal incipient faults in addition to inrush currents and internal faults. The relay issues an alarm signal in the case of the incipient fault but restrains during the magnetising inrush current. If an internal fault is recognised, the relay will issue a trip signal. To study the robustness of the suggested method, a program is developed in the MATLAB environment. The inputs of this program are differential current signals, derived from a system modelled by EMTP software. In order to simulate the internal incipient fault along with internal turn to turn and turn to earth faults, the transformer is modelled as 8 × 8 RL matrices, derived by using subroutine BCTRAN in EMTP. Also, differential currents are contaminated by noise and it is shown that the suggested method is not affected by noise and it can discriminate incipient faults, inrush currents, internal faults and external faults.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hyperbolic S-transform-based method for classification of external faults, incipient faults, inrush currents and internal faults in power transformers

Ashrafian

Rostami

Gharehpetian

2012

IET Gener. Transm. Distrib.

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“…de-noising process [12][13][14]. However, the S-transform is less influenced by noise [15][16][17]. S-transformbased techniques have been reported to deal with the noise problem in power transformer differential protection system [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Detection of internal incipient faults in transformers during impulse test using hyperbolic S-transform

Ashrafian

Naderi

Gharehpetian

2012

Int. Trans. Electr. Energ. Syst.

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In this paper, the application of the hyperbolic S-transform is proposed for detecting internal incipient faults of transformers during the impulse test. This test is performed on the under consideration transformer and during this test, the input current and applied voltage are recorded. The S-transform is applied to the recorded input current. An index is proposed and computed considering absolute deviations of the S-matrix. Faulty and non-faulty windings are discriminated by using the suggested index. The data obtained from field tests of a 66 kV/25MVA interleaved transformer winding and computer simulations, are recorded. Then, these data are fed to the proposed method, and faulty and normal conditions are discriminated, accordingly. Also, a wavelet-based method is implemented in MATLAB environment and the proposed method is compared with the wavelet-based method. According to simulations and experimental results, the proposed method is superior to wavelet transform-based method.

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“…Ashrafian, M. Rostami, G. B. Gharehpetian, and M. Gholamghasemi generalized window with a hyperbolic window [9]: …”

Section: Application Of Discrete S-transform For Differential Protectmentioning

confidence: 99%

“…f denotes the frequency and  is a parameter which controls the position of Gaussian window on the t-axis. The generalized S-transform can be obtained from original S-transform by replacing the Gaussian window with a generalized window [9]:…”

Section: The Hyperbolic S-transformmentioning

confidence: 99%

Application of Discrete S-Transform for Differential Protection of Power Transformers

Ashrafian¹,

Rostami²,

Gharehpetian³

et al. 2012

IJCEE

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Abstract-In this paper, a novel scheme based on Hyperbolic S-Transform (HST) is proposed for digital differential protection of power transformers. Hyperbolic S-transform is a powerful tool for non-stationary signal analysis in noisy conditions. Decision logic has been devised using extracted feature from differential currents due to transient phenomena in transformers. The HST of the differential current is calculated. Then, a Decision Index (DI) is calculated according to the spectral energy and standard deviation of the S-matrix. It is seen that DI values are different in the cases of internal faults and inrush currents. The scheme has been implemented in MATLAB environment and the inputs are differential currents derived from EMTP software. In order to simulate the internal turn to turn and turn to earth faults, the power transformer is modeled using 8×8 RL matrices obtained from the subroutine BCTRAN of EMTP software. The differential current signals are infected by noise and the robustness of the algorithm under noisy conditions is investigated.

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A new technique to classify transient events in power transformer differential protection using S-transform

Cited by 14 publications

References 19 publications

Hyperbolic S-transform-based method for classification of external faults, incipient faults, inrush currents and internal faults in power transformers

Hyperbolic S-transform-based method for classification of external faults, incipient faults, inrush currents and internal faults in power transformers

Detection of internal incipient faults in transformers during impulse test using hyperbolic S-transform

Application of Discrete S-Transform for Differential Protection of Power Transformers

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