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Articles by S. Sudha
Total Records ( 4 ) for S. Sudha
  S. Sudha and A. Ebenezer Jeyakumar
  This study compares Artificial Neural Network (ANN) based power transformer protection and Wavelet combined Neural Network (WNN) based power transformer protection for classification of internal fault current and inrush currents in three phase power transformers. A typical 100 MVA, 110/220KV, /Y three phase power transformer connected between a 110KV source at the sending end and a 220KV transmission line connected to an infinite bus power system at the receiving end were simulated using PSCAD/EMTDC software. The generated data were used by the MATLAB software to test the performance of the proposed technique. The simulation results obtained show that the WNN based algorithm is faster, more reliable and accurate when compared to ANN based algorithm. It provides a high operating sensitivity for internal faults and remains stable for inrush currents of the power transformers.
  S. Sudha and A. Ebenezer Jeyakumar
  This study presents a new, efficient, fast and reliable technique to discriminate internal faults from no fault conditions (inrush condition, normal, over excitation and external faults with CT saturation) in 3 phase transformers. A typical 100 MVA, 110/220 KV, Δ/Y 3 phase transformer connected between a 110 KV source at the sending end and a 220 KV transmission line connected to an infinite bus power system at the receiving end are simulated using PSCAD/EMTDC software. Various types of fault and no fault conditions are simulated and the differential currents are obtained. Wavelet transformation is done on the differential current and the d1 coefficients are obtained. The d1 coefficients are given as inputs to the wavelet based neural network trained by Particle Swarm Optimization (PSO-WNN). The simulation results show that PSO-WNN has very simple architecture, negligible error and provides more accurate results when compared to wavelet combined neural network trained by back propagation algorithm (WNN) and neural network trained by giving 3 phase differential currents as input (ANN). The performance of PSO-WNN based relay is also compared with the conventional harmonic blocking relay. PSO-WNN based relaying provides a high operating sensitivity for internal faults and remains stable for no fault conditions of the power transformers.
  S. Sudha , G.R. Suresh and R. Sukanesh
  This study proposes an adaptive, data-driven threshold for image denoising via wavelet soft-thresholding based on the Generalized Gaussian Distribution (GGD) widely used in image processing applications. The proposed threshold is simple and it is adaptive to each sub band because it depends on data-driven estimates of the parameters. In this proposed method, the choice of the threshold estimation is carried out by analyzing the statistical parameters of the wavelet sub band coefficients like standard deviation, variance. Our method describes a new method for suppression of noise in image by fusing the wavelet denoising technique with optimized thresholding function improving the denoised results significantly. Simulated noise images are used to evaluate the denoising performance of proposed algorithm along with another wavelet-based denoising algorithm. Experimental results show that the proposed denoising method outperforms standard wavelet denoising techniques in terms of the PSNR and the prevented edge information in most cases. We have compared this with various denoising methods like wiener filter, VisuShrink and BayesShrink.
  G.R. Suresh , S. Sudha and R. Sukanesh
  Region-based coding is an important feature provided in today’s image coding schemes including SPIHT and JPEG2000 as it allows different regions of interest in an image to be encoded at different bit rates and hence at different qualities rather than encoding the entire image with a single quality constraint. This study proposes an algorithm for three-dimensional region-based coding of volumetric medical datasets like MRI sequence. A 3D SA-DWT is used to decompose the data with multiple, arbitrarily shaped regions to obtain the representation of the regions in the transform domain. Then, a modified 3D SPIHT coding algorithm based on an unbalanced 3 structure is adopted in 3D region-based coding. This coding scheme offers good rate-distortion performance with additional features such as distortion scalability and flexibility in precise rate control. Experimental results show that the proposed algorithm outperforms the other coding schemes based on SPIHT algorithm in terms of R-D performance and quality of the image.
 
 
 
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