Browsing by Author "Nagaraj, C."

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Bi-directional power flow control with improved power quality using intelligent controller for AC-DC coupled hybrid micro-grid system
(Inderscience Publishers, 2021) Nagaraj, C.; Manjunatha Sharma, K.
Grid connected renewable sources are affected by harmonic distortion due to non-linear power electronics interfaces. Depending upon the nature of the load, many conversion stages are incorporated in the micro-grid which leads to increase in the losses. Therefore, in this paper, the AC-DC coupled hybrid micro-grid system is presented in which AC renewable sources and AC loads are connected to AC sub-grid and DC renewable sources and DC loads are connected to DC sub-grid. The shunt active power filter based 3? 4-leg bi-directional intermediate converter using d-q load current technique is proposed to achieve the power flow between AC and DC sub-grids. The MATLAB simulation is carried out, and the performance of the proposed system is analysed using the d-q load current technique based fuzzy logic and PI controller. The obtained results demonstrate that the overall system performance is improved with the d-q load current technique based fuzzy logic controller. © © 2021 Inderscience Enterprises Ltd.
Coordinated bidirectional power flow management with power quality improvement in AC-DC hybrid micro-grid under unbalanced Scenario
(Islamic Azad University ijes@mshdiau.ac.ir, 2019) Nagaraj, C.; Manjunatha Sharma, K.M.
The present day electrical power system is highly complex due to the increase in load demand and distributed generations. Further, the intermittent renewable sources and non-linear power electronic loads connected to the grid deteriorates the power quality of the system. Also, the more and more DC loads like LED lights to save energy consumption are connected to the AC distribution system. These issues can be effectively addressed using the smart micro-grid system. In an individual AC or DC micro-grid, the higher number of AC-DC-AC/DC-AC-DC power conversion stages lead to the increased power losses. Therefore, in this paper, an AC-DC hybrid micro-grid topology is proposed, wherein, AC sources and AC loads are connected to AC grid while DC sources and DC loads are connected to DC grid there by reducing the power conversion losses. The shunt active power filter based 3-phase 4-leg bidirectional interlinking converter using d-q reference current method with PI control is proposed to accomplish the inverter-based & rectifier-based power exchange between AC & DC sub-grids with harmonic current compensation under various grid and load conditions. The analysis is carried out in MATLAB/SIMULINK and results proving the improved power quality. © 2007-2017 Majlesi Branch, Islamic Azad University.
Effect of multidirectional forging on grain structure and mechanical properties of hypereutectic Al–20%Si alloys with added refiners and modifiers; Effet du forgeage multidirectionnel sur la structure des grains et les propriétés mécaniques des alliages hypereutectiques Al-20%Si avec des agents d’affinage et modificateurs ajoutés
(Taylor and Francis Ltd., 2025) Nagaraj, C.; Dutt, K.M.; Manjunath, G.K.; Sharath, P.C.; Sollapur, S.B.; B R, B.K.; Kumar, B.; Arunkumar, D.T.
The present work is focused on the multidirectional forging (MDF) of Al–20 wt-% Si alloys with the addition of refiners and modifiers. The MDF process was performed at 200°C with a cumulative strain of 0.63. Microstructural characterization and mechanical performance were evaluated on the Al–20Si, Al–20Si–4.5Cu, Al–20Si–4.5Cu–1(Al–Ti–B), Al–20Si–4.5Cu–1(Al–Ti–B)–10(Al–Sr). The microstructure analysis revealed significant changes in the eutectic and primary phase refinement. The micro-Vickers hardness confirmed that the MDF process resulted in increased hardness (125 ± 1.9 VHN) compared to the homogenized samples (96 ± 2.7 VHN). Tensile test results showed that with the accumulation of strain, ultimate tensile strength increased to 435 MPa from 302 MPa with reduction in the percentage of elongation from 7.8 to 5.6. The grains were more uniformly distributed with addition of modifiers, and refiners further reduced the nucleation number of eutectic grains. The wear study demonstrated that the wear resistance is more in the Al–Si-Cu-Sr sample due to the increased level of hardness. The combination of multidirectional forging techniques with judicious incorporation of refiners and modifiers engenders a synergistic enhancement of microstructural integrity, hardness profiles, and wear-resistant properties in hypereutectic Al-20Si alloys. © 2024 Canadian Institute of Mining, Metallurgy and Petroleum.
Fuzzy PI controller for bidirectional power flow applications with harmonic current mitigation under unbalanced scenario
(AIMS Press, 2018) Nagaraj, C.; Manjunatha Sharma, K.
The depletion of fossil fuels and environmental concern forces the extraction of power from low carbon fuels causes generation problem due to intermittent solar-wind renewable energy sources and power electronic applications. Furthermore, the significant amount of non-linear loads in the system causes power quality problems. Nowadays, the more and more DC loads like LED lights to save energy consumption are connected to the AC distribution system. These DC loads are connected at DC grid side in order to avoid the extra AC/DC power conversion loss. In this paper, the proposed d-q reference current method applied for shunt active power filter based 3-phase 4-leg bidirectional interfacing converter with fuzzy PI controller to achieve the real power transfer between DC grid side and AC grid side with current harmonics compensation at common connecting point simultaneously under balanced and unbalanced distorted grid and non-linear load conditions. The hysteresis current control comparator without PLL is used to compare actual grid current with reference filter current and generate the switching pulses for driving the bidirectional interfacing converter. The DC grid shunt connected intermittent hybrid solar-wind energy sources are integrating with AC grid utility through bidirectional interfacing converter has been into consideration for simulation studies. The MATLAB/SIMULINK tool is used to yield the improved grid current THD with fuzzy logic controller over PI controller. © 2018 the Author(s), licensee AIMS Press.
Harmonic current compensation improvement at point of common coupling using hybrid natural green sources
(2017) Nagaraj, C.; Sharma, K.M.
Ideally, distribution utilities are responsible to provide good power at a fixed rated frequency to the consumer end at unity power factor. Due to the bulk usage of non-linear power electronic loads, distribution system network (DSN) suffers large current distortion. Further, the intermittent hybrid natural green sources (HNGS) like PV and PMSG wind grid connected using hysteresis current controller (HCC) through 3-phase VSI effects more distortion of current which contaminates the power quality at the consumer end. Thus power quality is a vital issue which needs to be presented well in this paper. This paper adopts the shunt active filter (SHAF) using real and reactive current (id-iq) control strategy to analyze the case studies with presence and absence of HNGS under unbalanced nonlinear load condition for the reduction in current distortion at distribution utility side. The MATLAB/Simulink examined to validate the performance of id-iq control strategy. � 2017 IEEE.
Harmonic current compensation improvement at point of common coupling using hybrid natural green sources
(Institute of Electrical and Electronics Engineers Inc., 2017) Nagaraj, C.; Manjunatha Sharma, K.
Ideally, distribution utilities are responsible to provide good power at a fixed rated frequency to the consumer end at unity power factor. Due to the bulk usage of non-linear power electronic loads, distribution system network (DSN) suffers large current distortion. Further, the intermittent hybrid natural green sources (HNGS) like PV and PMSG wind grid connected using hysteresis current controller (HCC) through 3-phase VSI effects more distortion of current which contaminates the power quality at the consumer end. Thus power quality is a vital issue which needs to be presented well in this paper. This paper adopts the shunt active filter (SHAF) using real and reactive current (id-iq) control strategy to analyze the case studies with presence and absence of HNGS under unbalanced nonlinear load condition for the reduction in current distortion at distribution utility side. The MATLAB/Simulink examined to validate the performance of id-iq control strategy. Â© 2017 IEEE.
Improvement of harmonic current compensation for grid integrated PV and wind hybrid renewable energy system
(2016) Nagaraj, C.; Sharma, K.M.
Ideally, electric utilities are required to supply sinusoidal voltage at constant rated frequency while end users need to receive a sinusoidal current with good power factor. Electrical power distribution systems are already experiencing distortion of the current due to the usage of non-linear power electronic loads in industrial and commercial applications. Further, the integration of intermittent hybrid renewable sources like solar and wind to the utility grid through 4-leg 3-phase 4-wire current controlled voltage source inverter (VSI) leads to cause still more current distortion which pollutes the quality of electric power at the end users. Thus power quality is a critical issue to be addressed effectively. The active power filter (APF) is advantageous over passive filter due to its capability for better harmonic compensation features. This paper presents analysis of shunt active filter (SHAF) using a PI controller with and without the incorporation of intermittent hybrid renewable sources under different grid conditions. An instantaneous real and reactive current (id-iq) control scheme for SHAF is proposed for reduction in harmonic levels. The MATLAB/Simulink simulation studies validates the performance of id-iq control method. � 2016 IEEE.
Improvement of harmonic current compensation for grid integrated PV and wind hybrid renewable energy system
(Institute of Electrical and Electronics Engineers Inc., 2016) Nagaraj, C.; Manjunatha Sharma, K.M.
Ideally, electric utilities are required to supply sinusoidal voltage at constant rated frequency while end users need to receive a sinusoidal current with good power factor. Electrical power distribution systems are already experiencing distortion of the current due to the usage of non-linear power electronic loads in industrial and commercial applications. Further, the integration of intermittent hybrid renewable sources like solar and wind to the utility grid through 4-leg 3-phase 4-wire current controlled voltage source inverter (VSI) leads to cause still more current distortion which pollutes the quality of electric power at the end users. Thus power quality is a critical issue to be addressed effectively. The active power filter (APF) is advantageous over passive filter due to its capability for better harmonic compensation features. This paper presents analysis of shunt active filter (SHAF) using a PI controller with and without the incorporation of intermittent hybrid renewable sources under different grid conditions. An instantaneous real and reactive current (id-iq) control scheme for SHAF is proposed for reduction in harmonic levels. The MATLAB/Simulink simulation studies validates the performance of id-iq control method. Â© 2016 IEEE.
Integration of hybrid solar-wind energy sources with utility grid for improving power quality
(Institute of Electrical and Electronics Engineers Inc., 2018) Nagaraj, C.; Manjunatha Sharma, K.M.
Most of the utilities are suffering to provide continues and clean power at the end users due to grid current distortion in the distribution system because of non-linear low power electronics loads. In addition to this, freely available inherent hybrid solar-wind energy sources are leads to cause some more grid current distortion. Adverting to the above major issue over long decade, this paper presents an efficient controller for 3-phase 4-leg interfacing voltage source inverter to perform not only current harmonic reduction but also optimal real power transfer, neutral current compensation and power factor correction simultaneously. These multiple functions can be achieved efficiently by using id-iq control based shunt active power filter. The hysteresis comparator control is used to compare the obtained reference currents from id-iq control with actual sensed actual currents to generate the error signal. This error signal decides the working of the inverter switches. The simulation is carried out by using MATLAB/SIMULINK tool under different grid and load conditions and the corresponding simulated results are encouraged. Â© 2018 IEEE.