DSTATCOM APPLICATION FOR POWER QUALITY IMPROVEMENT IN DISTRIBUTION SYSTEM

J.R.P.Gupta,Alka Adya,Bhim Singh,A.P.Mitta 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-

Good quality power supply is a prerequisite for industrial growth. Power quality and reliability cost the industry large amounts each year. Hence, a major challenge for engineers these days is to use the advances in Power Electronic devices and technology to control power flow and provide adaptable, fastacting reactive power correction to changing electrical loads. FACTS (Flexible AC Transmission System) controllers have revolutionized the world in the area of generation, transmission and distribution of power. This paper focuses on DSTATCOM (Distribution Static Synchronous Compensator) which is gaining popularity along with other custom power devices like DVR (Dynamic Voltage Restorer) and UPQC (Unified Power Quality Compensator). This paper deals with various aspects like design, modeling and simulation of DSTATCOM for the power quality improvements.

Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

Mathur, S.,Gupta, A.,Page, K.,Pogge, R. W.,Krongold, Y.,Goad, M. R.,Adams, S. M.,Anderson, M. D.,Aré,valo, P.,Barth, A. J.,Bazhaw, C.,Beatty, T. G.,Bentz, M. C.,Bigley, A.,Bisogni, S.,Borman, G. American Astronomical Society 2017 The Astrophysical Journal Vol.846 No.1

<P>During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on-and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly.</P>

Photoluminescence, thermoluminescence and evaluation of some parameters of Dy³⁺ activated Sr₅(PO₄)₃F phosphor synthesized by sol-gel method

Gupta, K.K.,Kadam, R.M.,Dhoble, N.S.,Lochab, S.P.,Singh, V.,Dhoble, S.J. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.688 No.2

In this study, we have synthesized Dy<SUP>3+</SUP> activated Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F (S-FAP) phosphors by sol-gel synthesis method. The synthesized phosphors were characterized by X-ray diffraction pattern (XRD), scanning electron microscopic (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescent properties. Dy<SUP>3+</SUP> activated Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphor shows its characteristic PL emission at 481 nm and 574 nm due to <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>15/2</SUB> and <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>13/2</SUB> transitions, respectively. TL characteristics of Dy<SUP>3+</SUP> doped Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphors were taken after irradiation by <SUP>60</SUP>Co gamma exposure. Two separate TL peaks at 126 <SUP>o</SUP>C and 279 <SUP>o</SUP>C were observed in case of Dy<SUP>3+</SUP> doped phosphor. Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor was irradiated within a wide range of exposure of 50 Gy to 7 kGy doses. Linearity was found up to 2 kGy and thereafter TL response saturates. Fading study was also carried out over the duration of six weeks for Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphor. Trapping parameters were calculated using Chen's peak shape method, initial rise method and various heating rate method. Glow curve is deconvoluted using computerized glow curve deconvolution program. TL sensitivity of Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor is found to be less by a factor of 2.08 than commercially used CaSO<SUB>4</SUB>:Dy phosphor. In order to identify the defect centers formed upon γ-ray irradiation in Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor, EPR measurements were carried out on un-irradiated and irradiated phosphors.

Triethylammonium acetate ionic liquid assisted one-pot synthesis of dihydropyrimidinones and evaluation of their antioxidant and antibacterial activities

Attri, P.,Bhatia, R.,Gaur, J.,Arora, B.,Gupta, A.,Kumar, N.,Choi, E.H. Elsevier ; King Saud University 2017 Arabian journal of chemistry Vol.10 No.2

<P>A mild and efficient catalytic method has been developed to synthesize 3,4-dihydropyrimidinones in high yield by one-pot three component Biginelli condensation in the presence of triethylammonium acetate (TEAA) which acts as catalyst/reaction medium. Further, we have studied the antioxidant and antibacterial activities of these synthesized 3,4-dihydropyrimidinones. All the synthesized compounds reveal the significant antioxidant properties, these properties have been studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and cupric reducing antioxidant capacity (CUPRAC) assays. In addition, to this, these compounds also show the good antibacterial activity against four human pathogenic bacteria. (C) 2014 King Saud University. Production and hosting by Elsevier B.V.</P>

Kharitonov’s Theorem and Routh Criterion for Stability Margin of Interval Systems

Yogesh V. Hote,J. R. P. Gupta,D. Roy Choudhury 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.3

In this paper, it is shown that the gain margin and phase margin of interval system can be determined analytically using Kharitonov’s theorem and V. Krishnamurthi’s corollary on Routh criterion without using graphical and iterative techniques. Further, it is proved that the existing results of Anderson et al. [2] on the stability of low-order interval systems using Kharitonov’s theorem are only applicable for absolute stability of the interval system and it is not applicable for relative stability of the interval systems, i.e., for phase margin. The proposed technique and stability analysis for low-order interval systems are verified with examples.

Wrapper Based Wavelet Feature Optimization for EEG Signals

Girisha Garg,A.P. Mittal,Vijander Singh,J.R.P Gupta 대한의용생체공학회 2012 Biomedical Engineering Letters (BMEL) Vol.2 No.1

Purpose In this paper a computationally efficient wrapper based Wavelet Feature Optimization (WFO) is developed. The algorithm is developed for the classification of high dimensional EEG signals which may suffer from the curse of dimensionality and sub optimal feature selection. Methods The key design phases of the algorithm involve: 1)Feature Transformation of the original EEG signals using Discrete Wavelet Transform; 2) Feature Extraction using the concept of Relative Wavelet Energy (RWE) 3) Selecting the optimal subset of the RWE features using wrapper approach. In contrast to the methods guided by the filter technique of feature selection, this approach uses the wrapper based method to select the optimal and a very low dimensional feature space from the wavelet features. Results The highlight of the algorithm is that in addition to increase the computational efficiency, it also enhances the predictive power of the system without any loss of relevant information. This paper includes the experimentation performed on EEG datasets using WFO algorithm. Conclusions The algorithm gives consistent and excellent performance for the EEG datasets. The feature sets obtained with the help of WFO are also tested using mutual information methods to confirm the optimality of the wavelet feature subset.

Multi-Secondary Transformer: A Modeling Technique for Simulation - II

Patel, A.,Singh, N.P.,Gupta, L.N.,Raval, B.,Oza, K.,Thakar, A.,Parmar, D.,Dhola, H.,Dave, R.,Gupta, V.,Gajjar, S.,Patel, P.J.,Baruah, U.K. Journal of International Conference on Electrical 2014 Journal of international Conference on Electrical Vol.3 No.1

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

On Robust Stability of the Systems

Yogesh V. Hote,D. Roy Choudhury,J. R. P. Gupta 제어·로봇·시스템학회 2009 International Journal of Control, Automation, and Vol.7 No.3

In this paper, to check robust stability for higher order interval systems a step-by-step procedure is presented using simple conditions, on the basis of Routh criterion. In this, it is pointed out that there is no need to apply Routh criterion to all the four Kharitonov’s polynomials in some class of control system problems, and hence reduces the computational cost. Numerical examples illustrate the procedure.

New Approach for Stability of Perturbed DC-DC Converters

Hote, Yogesh V.,Choudhury, D. Roy,Gupta, J.R.P. The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1

In this paper, a simple technique is presented for robust stability testing of perturbed DC-DC converters having multi-linear uncertainty structure. This technique provides a necessary and sufficient condition for testing robust stability. It is based on the corollary of Routh criterion and gridding of parameters. The previous work based on parametric control theory using Kharitonov's theorem and Hermite Biehler theorem gives conservative results and only the sufficient condition of stability, whereas the proposed method provides the necessary and sufficient condition for testing robust stability and it is computationally efficient. The superiority of the method is compared with the Edge theorem.

Torque Ripples Minimization of DTC IPMSM Drive for the EV Propulsion System using a Neural Network

Bhim Singh,Pradeep Jain,A.P.Mittal,J.R.P.Gupta 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.1

This paper deals with a Direct Torque Control (DTC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) for the Electric Vehicle (EV) propulsion system using a Neural Network (NN). The Conventional DTC with optimized switching lookup table and three level torque controller generates relatively large torque ripples in an electric vehicle motor drive. For reducing the torque ripples, a three level torque controller is hereby replaced by the five level torque controller. Furthermore, the switching lookup table of the five level torque controller based DTC is replaced with a Neural Network. These DTC schemes of an IPMSM drive are simulated using MATLAB/SIMULINK. The simulated results are compared with the conventional DTC and it is found that the ripples in the torque, as well as in the stator current, are reduced drastically.