Conference Papers
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Item Development of wavelet transform based numeric relay for differential protection of power transformer(2003) Vittal, K.P.; Gaonakar, D.N.; Fakruddin, D.B.This paper proposes the wavelet transform (WT) based algorithm useful in digital differential protection of transformer. It is shown that, the wavelet transform has more distinct feature extraction property, due to its ability to extract information from the transient signals, simultaneously both in time and frequency. A decision logic has been devised using extracted feature from differential current, so as to distinguish an internal fault from an inrush / over-excitation. The proposed algorithm is evaluated using simulated inrush, over-excitation and internal fault current signals. For this purpose a transient behavioral model of power transformer has been developed using MATLAB software. Results of evaluation study show that, proposed WT based differential protection scheme can over come the problem of false tripping due to inrush/over-excitation.Item Electrical fault detection in three phase squirrel cage induction motor by vibration analysis using MEMS accelerometer(2005) Maruthi, G.S.; Vittal, K.P.The ever increasing applications of 3phase Induction motor have resulted in a growing awareness on addressing various performance demands. The condition monitoring of these electrical machines has received considerable attention in recent years. The diagnostics based on vibrations produced by these motors can form valuable data for preventive maintenance of these machines. The vibration analysis demands appropriate vibration transducer. With the advent of MEMS [Micro Electro Mechanical Systems], Technology I.C. chip mounted accelerometers are available. These accelerometers are having merits of low cost, high reliability, and low power consumption when compared to piezoelectric types which are conventionally used earlier. These accelerometers are gaining wide acceptance in condition monitoring of electrical machines. This paper presents the instrumentation developed around MEMS accelerometer and also proposes a technique of detecting abnormal electrical operating conditions in 3phase Induction motor such as single phasing, voltage unbalance by employing spectrum analysis of vibrations measured through MEMS accelerometer. © 2005 IEEE.Item Investigations on Combined Operation of Industrial Distribution System and utility in Distributed Generation Environment(2006) Manjunatha Sharma, K.; Vittal, K.P.; Nagaraja Rao, T.K.The deregulation regime has given lot of scope for independent power producers to feed power to the utility nearest to the load center. This feature provides opportunities for lot of improvements in distribution system operation. In this paper investigations have been done for integrated operation of the practical MRPL industrial distribution plant having its own captive generation to act as distributed generation source serving neighboring utility loads. The performance of the system is simulated in both cases of industry acting as source and sink depending on the load cycle. The simulation results will serve as useful tool for decision making in power trading during ABT regime. ©2006 IEEE.Item Computer controlled intrusion-detector and automatic firing-unit for border security(2010) Vittal, K.P.; Ajay, P.P.; Shenoy, S.B.; Srinivas Rao, C.H.S.This paper describes a novel computer-controlled intrusion-detector and automatic firing unit, which may be used for the surveillance of borders, either of a country, or of areas requiring high security, especially in regions of extreme climatic conditions, where it is difficult to deploy personnel. This system not only detects intrusion but also provides a video-coverage of the suspicious area, for remote vigilance, via a satellite based communication system. It is also provided with automatic firing mechanisms which can be used to automatically locate and fire at the target. Thus, several kilometres of the borders, which would have otherwise required several hundred personnel, can be effortlessly monitored with this system, with only a few personnel. Since, the actual firing occurs only after an authoritative personnel has doubly confirmed the presence of an intruder, chances of firing at innocent people are completely ruled out. As thermal cameras are used for imaging, this system is immune to changes in ambient conditions, and therefore, is equally suited for operation during the night. This paper also throws light on the prototype of this system, which has been successfully developed. © 2010 IEEE.Item DQ modeling of induction motor for virtual flux measurement(2010) Sushma, P.; Rajalakshmi Samaga, R.; Vittal, K.P.Three phase induction motors are continuing to remain as work horses in industrial applications. The accurate behavioral modeling of induction motor helps in designing controller for the machine and also useful in detection of faults in machines. Almost all faults in the induction motor affect the flux in the air gap. These fluxes can be measured virtually using dq model of induction motor by feeding voltage and current values extracted in real time and stored. In this paper, DQ model is developed in stator reference frame using MATLAB-SIMULINK platform and a data acquisition system supported with LabVIEW is used to obtain motor terminal voltage and current signals which are useful in estimation of flux in an actual machine. ©2010 IEEE.Item Space time coding for data transmission over power line channel(2010) Itagi, R.; Vittal, K.P.; Sripati, U.Power line channel for data transmission using digital modulation is considered to be used for sub station automation. Because of time-varying nonwhite noise being present on power line, power line channel can be modeled as multipath channel. Middleton Class-A noise model is used to simulate impulse noise on power line. The concept of space and time diversity given by Almouti, known as space time coding is used for data transmission over power line channel. Space time coding requires channel estimation, which is performed using pilot symbol data. Combination of BCH code concatenated with Convolution Turbo code employed as error correcting code ensures proper data recovery under severe channel disturbances. © 2010 IEEE.Item Adaptive distance relaying scheme in series compensated transmission lines(2010) Srivani Iyengar, S.G.; Vittal, K.P.The introduction of the capacitance in series with the line reactance adds certain complexities to the effective application of impedance based distance relays. The paper reviews series compensated line protection challenges and proposes the state of art relay with an integrated scheme in harmony with the present power system scenarios Development of the proposed scheme is in the specific area of incorporating the adaptive features like adaptive Relay setting as the compensation level changes in the series compensated lines of the transmission system for optimum reliability. Upon extensive testing on different data set of fault cases with fault resistance and varying percentage compensation level, performance of the developed method ensures that the proposed scheme overcomes the overreach / underreach problem of the distance relay in series compensated lines and is found to be quite promising.Item Space time coding for power line communication(2011) Itagi, R.; Vittal, K.P.; Sripati, U.A study of Power Line as communication medium for broadband or narrowband application is performed in the perspective of space time coding. Simulation study to send modulated data on two phases of power line and receive signal between two phases and analyze is performed. Middleton class-A noise is used to model the noise on power line. BCH coding is used for error correction. Recovery of data, when at least one path of the channel is with medium attenuation, when simultaneously the other path of the channel goes worse is verified. The results are found to be in accordance with the principle of space time coding scheme and provide the possibility of utilizing power line as effective means of communication. © 2011 IEEE.Item Investigation into effect of mixed air gap eccentricity on dq components of currents in induction motor(2011) Rajalakshmi Samaga, R.; Vittal, K.P.dq components of currents are extensively used in the controller applications of industrial drives as they are dc quantities. In this paper, it is shown that these components will no longer remain as dc quantities, if they are extracted from the induction motor suffering from mixed air gap eccentricity. A dynamic model of an induction motor suffering from mixed air gap eccentricity is developed and simulated to show the presence of eccentricity characteristic harmonics in dq components of the stator currents in synchronous reference frame. In this paper, it is also shown that the frequency analysis of dq currents helps in the detection of air gap non uniformity in the machine. The results obtained by modeling and simulation are also validated experimentally. © 2011 IEEE.Item Air gap mixed eccentricity severity detection in an induction motor(2011) Rajalakshmi Samaga, R.; Vittal, K.P.Non invasive fault detection unit for an induction motor has become an integral part of industrial drives. As the current is the primary quantity to get affected by the non uniform air gap flux, Motor Current Signature Analysis is preferred as compared to vibration analysis for mixed eccentricity fault detection in an induction motor. In this paper, Power Spectral Density analysis is performed on the stator current data samples obtained from modeling and simulation of the induction motor. An Eccentricity Severity Factor is defined and is shown that this factor increases with increase of air gap eccentricity in the machine. Hence it can be used as a measure to assess the degree of eccentricity in the machine. © 2011 IEEE.