Journal Articles

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884

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Subject: search.filters.subject.Electric power factor

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Now showing 1 - 7 of 7
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    Comprehensive study of mixed eccentricity fault diagnosis in induction motors using signature analysis
    (2012) Rajalakshmi Samaga, B.L.; Vittal, K.P.
    Modeling and simulation studies of an induction motor always help in identifying the parameter to characterize the asymmetrical fault in the machine. Hence in this paper, an air gap eccentric induction motor is modeled using multiple coupled circuit approach and 2D-Modified Winding Function Theory. The machine model is simulated under different eccentricity conditions to obtain the motor current spectra, power spectra and power factor spectra to detect the eccentricity related frequency components and the results are compared. All these analysis are based on the variation in the amplitude of mixed eccentricity related frequency component in these parameters with the variation in the level of eccentricity in the machine. A new fault severity detection method based on co-variance analysis is presented to predict the degree of deterioration in the health of the machine due to air gap eccentricity from the installation stage. © 2011 Elsevier Ltd. All rights reserved.
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    An effective reference generation scheme for DFIG with unbalanced grid voltage
    (Institute of Electrical and Electronics Engineers Inc., 2014) Asha Rani, M.A.; Nagamani, C.; Saravana Ilango, G.; Karthikeyan, A.
    This paper presents a reference current generation scheme for improved dynamic performance of a doubly fed induction generator (DFIG) subjected to unbalanced grid voltage. The power and torque oscillations induced due to the unbalance in grid voltage are minimized using additional compensatory terms in the reference currents. The focus is on estimating the reference currents and control implementation without the need for dual vector control. Real and reactive power control is implemented in the positive mbi d - q reference frame using stator flux-oriented vector control. The rotor-side converter (RSC) is controlled to enable effective reduction of oscillations in torque and active and reactive power. The dc-link voltage oscillation is minimized and the grid-side power factor is maintained unity using the grid-side converter (GSC). Unlike the previously reported techniques, the proposed scheme enables effective reduction of oscillations in torque, active, and reactive power, and the dc-link voltage, all in a single target. The performance of DFIG is investigated in consideration with the Indian Electricity Grid Code (IEGC). Numerical simulations are carried out in power system computer aided design/ electromagnetic transients including direct current (PSCAD/EMTDC) for the laboratory 3-hp DFIG test setup. The results establish that the performance of DFIG is notably enhanced with the proposed scheme. © 2014 IEEE.
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    Impact of Different PQ Models of Wind Turbine Generating Units (WTGUs) on System Voltage Performance
    (Walter de Gruyter GmbH info@degruyter.com, 2017) Moger, T.; Dhadbanjan, T.
    This paper presents the voltage performance analysis of the system with various types of wind turbine generating units (WTGUs). A detailed voltage performance analysis is carried out by considering the different PQ models used for computing the reactive power output of the WTGUs (fixed/semi-variable speed and variable speed WTGUs). The different PQ models of fixed/semi-variable speed WTGUs incorporated for the studies are voltage dependent model, voltage independent model, power factor based model, and PX model. In addition, the variable speed WTGUs are also considered in different fixed power factor mode of operation. Based on these models, a comparative analysis is presented. A modified 27-bus equivalent distribution test system with dispersed wind generation is considered for the studies. Further, the case studies have been carried out by considering the various wind power output levels of WTGUs to examine its impact on system voltage performance. From the comparative analysis, the power factor based model can be the best choice over the other models (which are based on voltages) for the system studies with fixed/semi-variable speed WTGUs. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.
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    Drastic increase in thermoelectric power factor of mixed Sb2Te3-In2Te3 thin films
    (Academic Press, 2019) Vallem, S.; Bangera, K.V.; G.k, S.
    Thermoelectric power factor is an indicator of the performance of a thermoelectric material. Attempts have been made by various techniques, like doping, to improve the thermoelectric conversion efficiency of materials. In the present study, a layer structured thermoelectric material Sb2Te3 is alloyed to In2Te3 using vacuum deposition method at 423 K to significantly enhance the power factor of ?118 ?Wm-1K?2 (at 450 K). Structurally, all films were polycrystalline in nature as clearly reflected in XRD patterns. All films were showing p-type conductivity, and electrical conductivity of In2Te3 films increased with increasing Sb2Te3 content. The seebeck coefficient is found to be higher for un-doped In2Te3 than that of Sb2Te3-In2Te3 and pure Sb2Te3 films. However, the thermoelectric power factor of 25% Sb2Te3 alloyed In2Te3 films is enhanced by 11.9 times that of In2Te3 films and 4 times that of Sb2Te3 films at 320 K. It is interesting to note that efficiency of the mixed films is higher than that of the individual films. © 2019 Elsevier Ltd
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    SnTe thermoelectrics: Dual step approach for enhanced performance
    (Elsevier Ltd, 2020) Bhat, D.K.; Shenoy, U.S.
    Doping of SnTe to achieve desirable properties has been a wide spread approach in the recent past to enhance its thermoelectric performance. Herein, we apply a dual approach: Pb doping for reduction of thermal conductivity and Zn doping for improving the power factor. The theoretical prediction of enhanced Seebeck due to increase in the band gap, introduction of the resonance levels by Zn and dominance of the heavy hole valence band, is realized experimentally as improved power factor throughout the temperature range. The accompanying reduction in the thermal conductivity by co-doping Pb and Zn leads to a record high room temperature figure of merit, ZT of 0.35 (@ 300K) and ZT of 1.66 at 840 K. The ZTaverage of ?0.9 with 300 K as cold end and 840 K as hot end sets a new record for SnTe based materials. © 2020 Elsevier B.V.
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    Computation of steady-state operating conditions of a DFIG-based wind energy conversion system considering losses
    (Springer Science and Business Media Deutschland GmbH, 2023) Karthik, D.R.; Manjarekar, N.S.; Kotian, S.M.
    In this paper, steady-state operating conditions of a doubly fed induction generator (DFIG) are computed considering losses of grid-side (GS) filter. Two different cases are studied for steady-state initialization of the DFIG-based wind turbine systems (WTS). In the first case, active power (P) and reactive power (Q) at DFIG terminals are assumed to be known. In the other case wind speed (Vw), Q is assumed to be known. Apart from considering losses of the DFIG and GS filter, both the cases also consider the non-unity power factor operation of the grid side converter (GSC). For the first case, steady-state operating conditions are calculated by iterative method as well as by non-iterative method. For the second case, iterative method is used to calculate steady-state operating conditions. Calculation of steady-state values of other subsystems of DFIG-based WTS like drive train, controller and network is also shown. The initial values calculated are validated and compared by performing modal analysis and time-domain simulations. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    A Single Source Quadruple Boost Nine-Level Switched-Capacitor Inverter with Reduced Components and Continuous Input Current
    (Institute of Electrical and Electronics Engineers Inc., 2024) Kumar, D.; Raushan, R.; Chakraborty, S.
    The multilevel inverter (MLI) serves as a pivotal class of power electronic converters, well-suited for high-power applications at medium voltage levels, ensuring superior power quality. While designing an MLI, there is a motif among the number of components, voltage stress on the semiconductor devices, and its voltage-boosting ability. A single source nine-level switched-capacitor based novel inverter with reduced components has been proposed in this paper. The proposed H-bridge based switched capacitor inverter topology employs nine switches, two capacitors, two diodes, and one DC source. The inverter has a quadruple voltage boost and the ability to draw continuous input current from the DC supply and self-voltage balance with a voltage ripple of less than 5%. A comprehensive study of performance parameters, design consideration, and loss analysis of the proposed inverter is also incorporated. A level-shifted pulse width modulation technique is implemented to operate the inverter for unity to 0.5 lagging load power factors and 1-0.2 modulation indices. The dynamic responses of the proposed switched capacitor inverter topology are obtained through MATLAB simulation for analysis and further validated by hardware prototype. © 2013 IEEE.