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CONTENTS TRANSIENT PROTETION OF • INTRODUCTION TRANSMISSION LINE • SINIFICANCE OF WAVELET TRANSFORM • SIMULATION OF FAULTED TRANSMISSION USING WAVELET TRANSFORM LINE 2/18 1/18 2/17

• ANALYSIS OF WAVELET TRANSFORM • WAVELET ANALYSIS OF FAULT CURRENT SIGNAL • WAVELET BASED ALGORITHM BY • ADVANTAGES P.VENKATESH & T.L.V.NAGA LATHISH • APPLICATIONS LAKKIREDDY BALREDDY COLLEGE

• CONCLUSION OF ENGG. • BIBLIOGRAPHYMYLAVARAM.

INTRODUCTION

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 Earlier digital relays have proven very useful and efficient in power system steady state analysis. Among these are kalman based transforms, Fourier transforms etc.  Due to the presence of non stationary signals the performance of these techniques are limited.  Recent solution to this problem is WAVELET TRANSFORM which was introduced by F.JIANG.

Significance of wavelet transform 4/18

 It has the capability of providing accurate transient information in both time and frequency domain.  It has a special feature of variable time frequency localization which is very different from windowed Fourier transform.  It is applied to decompose the current signal. The time and frequency domain features of transient signals are extracted the spectral energies of wavelet components are calculated and then employed to detect and classify the faults.

faulted transmission system

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 The simulation of above system was carried out by ATP-EMTP software and it included study of system for different fault types, fault positions and different fault inception angles.

WAVELET TRANSFORM

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 It transforms a time domain signal to timescale domain. This process of transformation is called signal decomposition because a signal is decomposed into several other signals with different level of resolution.  From these decomposed signals, it is possible to recover the original time domain signal perfectly. This reverse process is known as signal reconstruction.

WAVELET TRANSFORM  For a signal or function X(t) its continuous wavelet transform (CWT)IS

 Where

a = scaling parameter b = translation parameter Zi = mother wavelet function

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WAVELET TRANSFORM  For a signal or function X(k) its discrete wavelet transform (DWT) is

Where asterisk denotes a complex conjugate, the parameters a and b in Eq.( 1) are replaced by digitized parameters, also k and m are scale and time-shift parameters.

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Decomposition and reconstruction

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Wavelet analysis of fault current signal

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Wavelet based algorithm

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ADVANTAGES

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 Wavelet analysis provides accurate transient information in both time and frequency domain.

 It has become a very important tool for research in the field of mathematics, physics and engineering.  It develops the high speed protection relays with accurate fault detection and classification.

APPLICATIONS  Lightning over voltage studies.  Switching transients and faults.  Statistical and systematic over voltage studies.  Very fast transients in groundings.  Machine modeling.  Transient stability, motor startup.  Shaft torsional oscillations.  Power electronic applications.

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CONCLUSION

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The details and approximations up to three levels obtained from the wavelet decomposition of the current signals are used to detect and classify the faults. Numerical studies clearly show promising prospects for the application of wavelet analysis in power system protection

BIBILOGRAPHY Andersen Power Electronic Solutions Ltd

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