Journal Articles
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Item Comprehensive review on solar, wind and hybrid wind-PV water pumping systems-an electrical engineering perspective(China Power Supply Society, 2021) Angadi, S.; Yaragatti, U.R.; Yellasiri, Y.; Raju, A.B.In India, the demand for water is continuously increasing due to the growing population. Approximately 16.5% of all country's electricity used to pump this water is from fossil fuels leading to increased pump Life Cycle Cost (LCC) and Green House Gas (GHG) emissions. With the recent advancement in power electronics and drives, renewables like solar photovoltaic and wind energy are becoming readily available for water pumping applications resulting in the reduction of GHG emissions. Recently, research towards AC motor based Water Pumping Systems (WPS) has received a great emphasis owing to its numerous merits. Further, considering the tremendous acceptance of renewable sources, especially solar and wind, this paper provides a detailed review of single-stage and multi-stage WPS consisting of renewable source powered AC motors. The critical review is performed based on the following figure of merits, including the type of motor, power electronics interface and associated control strategies. Also, to add to the reliability of solar PV WPS, hybrid Wind-PV WPS will be discussed in detail. Readers will be presented with the state-of-the-art technology and research directions in Renewable Energy-based WPS (REWPS) to improve the overall system efficiency and hence reduce the payback period. © 2021 All rights reserved.Item Design of haul road lighting system. Part II: Design based on optimal cost considerations(2006) Karmakar, N.C.; Mangalpady, M.; Rao, Y.V.; Yaragatti, U.R.The proper selection of lighting installations is very important for the provision of cost-effective lighting systems without compromising light quality. In this study a computer program was developed to evolve a cost-effective lighting system for haul roads in surface mines. This program is beneficial in assessing the viability of various lighting installations in order to achieve cost-effective solutions. Using the program, illumination design was studied for an 800 m long stretch of haul road. Nine different types of light sources were considered at mounting heights of 12 m and 16 m. The study shows that at a 12 m mounting height, 100 W high-pressure sodium vapour (HPSV) lamps offer the most cost-effective design, followed by 250 W HPSV lamps. In the case of 16 m pole heights the annual lighting cost is minimum for 150 W HPSV lamps, followed by 250 W HPSV lamps. This work also shows that optimum design based on energy consumption need not be the same as design based on optimum cost considerations as cost parameters may vary widely with location.Item Design of haul road lighting system. Part I: Design based on optimal energy considerations(2006) Karmakar, N.C.; Mangalpady, M.; Rao, Y.V.; Yaragatti, U.R.Electrical energy consumption is a major cost component of haul road lighting. Haul road lighting depends on many parameters such as type and wattage of sources, mounting height and tilt angle of light fixtures. In this study a computer model has been developed for optimum energy consumption of any haul road lighting system. Using the program, illumination design was studied for a stretch of 800m long haul road. Nine different types of light sources were considered for mounting heights of 12 and 16m. High-pressure sodium vapour (HPSV) lamps of 100W proved to be energy efficient at a 12m height whereas at 16m height, energy consumption was minimum for 150 W HPSV lamps. Thus the developed computer program proved to be successful in evaluating the performance of lighting designs from the point of view of energy consumption.Item Rural electrification in India and feasibility of Photovoltaic Solar Home Systems(2011) Kamalapur, G.D.; Yaragatti, U.R.Rural electrification is an integral component of poverty alleviation and rural growth of a nation. In India, electricity has not played effective role in the socio-economic growth of village. Gross Domestic Product (GDP) is increasing with 8% where as contribution of agriculture sector is 1.9%. Government of India has ambitious target of providing electricity to all villages by 2008 and all rural households by 2012. Steps are already initiated with Rural Electric Corporation, Rural Electricity Supply Technology mission, State Electricity Boards, Reforms in Power sector. An attempt has been made in this paper to assess the features of rural electrification in India and the feasibility of Photovoltaic Solar Home Systems (PV SHS). © 2010 Elsevier Ltd. All rights reserved.Item Synchronized symmetrical bus-clamping PWM strategies for three level inverter: Applications to low switching frequencies(2011) Veeranna, S.B.; Yaragatti, U.R.; Beig, A.R.The digital control of three-level voltage source inverter fed high power high performance ac drives has recently become a popular in industrial applications. In order to control such drives, the pulse width modulation algorithm needs to be implemented in the controller. In this paper, synchronized symmetrical bus-clamping pulse width modulation strategies are presented. These strategies have some practical advantages such as reduced average switching frequency, easy digital implementation, reduced switching losses and improved output voltage quality compared to conventional space vector pulse width modulation strategies. The operation of three level inverter in linear region is extended to overmodulation region. The performance is analyzed in terms THD and fundamental output voltage waveforms and is compared with conventional space vector PWM strategies and found that switching losses can be minimized using bus-clamping strategy compared to conventional space vector strategy. The proposed method is implemented using Motorola Power PC 8240 processor and verified on a constant v/f induction motor drive fed from IGBT based inverter. © 2011 Berkeley Electronic Press. All rights reserved.Item Gridable Electric Vehicle (GEV) Aggregation in Distribution Network to Support Grid Requirements: A Communication Approach(Walter de Gruyter GmbH info@degruyter.com, 2017) Hampannavar, S.; Chavhan, S.; Yaragatti, U.R.; Naik, A.Electric Vehicles (EV) can be connected to the grid for power transaction and also serve as distributed resource (DR) or distributed energy storage system (DESS). The concept of connecting group of EVs or gridable EVs (GEV) to the grid is called Vehicle-To-Grid (V2G). V2G is a prominent energy storage system as it is flexible and can be used to support the grid requirements in order to meet the time varying load demand. Optimal placement of GEV aggregation in power distribution network is very challenging and helps in maintaining stability of the power system for a shorter duration of time. In this paper, algorithm is developed for estimating parameters like Ploss, Qloss, Vpu based on past history and wireless access support for Control and Monitoring Unit (CMU) to aggregator agent communication is proposed using Long Term Evolution (LTE) protocol. The load flow studies are carried using MiPOWER software in order to obtain the optimal location for the placement of GEV aggregation in power distribution network. LTE physical layer is modeled using MATLAB/SIMULINK and the performance is analyzed using bit error rate (BER) v/s signal to noise ratio (SNR) curves. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.Item Design and implementation of active neutralpoint-clamped nine-level reduced device count inverter: An application to grid integrated renewable energy sources(Institution of Engineering and Technology journals@theiet.org, 2018) Sandeep, N.; Yaragatti, U.R.Multilevel inverters are one of the preferred choices in medium-voltage and high-power applications in the recent past. Active neutral-point-clamped (ANPC) inverter is the most popular topology, especially in the class of five-level (5L) inverters. In this study, a nine-level topology with improved output waveform quality is proposed based on ameliorating the 5L ANPC inverter with least modifications. The addition of only two switches operating at line frequency to the conventional 5L ANPC inverter while maintaining an identical precursor part count is the proposed modification. A logic form equation-based active voltage balancing scheme that is independent of load current and power factor is developed to regulate the flying capacitor voltage at the reference value. The operating principle, salient features, and the developed control scheme are comprehensively detailed. The operation of the proposed inverter considering a grid integrated case is simulated in MATLAB/ Simulink, and the results corresponding to steady-state and dynamic conditions are presented. The benefits of the proposed topology are elucidated by comparing it with other classic topologies considering various prominent viewpoints. This comparison has illustrated the proposed topology's distinctive characteristics and profound advantages. The performance validation, feasibility, and practicability of the proposed inverter are established through the experimental results obtained from a laboratory-scale prototype. © The Institution of Engineering and Technology 2017.Item Simplified transformer-based multilevel inverter topology and generalisations for renewable energy applications(Institution of Engineering and Technology journals@theiet.org, 2018) Behara, S.; Sandeep, N.; Yaragatti, U.R.Multilevel inverters (MLIs) generating high-quality voltage waveforms are playing a significant role in renewable energy applications. However, the requirement of higher number of power devices, complex pulse-width-modulation (PWM) and voltage unbalancing issues are the impediments associated with their direct usage. Consequently, several attempts to devise MLIs with lesser number of overall components are witnessed. This study focuses on developing a nine-level inverter comprising of a single transformer and reduced component count. An optimisation of the number of transformers and their turn's ratio for a given number of voltage levels resulting in the least number of switches is investigated and deliberated in detail. Besides, an uncomplicated logic gate-based PWM strategy is developed for generating the gating signals of switches using simple Boolean logic relations. A detailed comparison with other recommended MLI topologies is presented to highlight the notable features of the proposed topology. Simulation results obtained using the model developed in MATLAB/Simulink along with the experimental measurements obtained from a downscale prototype is presented to validate the practicability, effectiveness, and viability of the proposed topology. An explicit agreement among the simulation and experimental results is observed. © The Institution of Engineering and Technology 2017.Item Operation and Control of a Nine-Level Modified ANPC Inverter Topology with Reduced Part Count for Grid-Connected Applications(Institute of Electrical and Electronics Engineers Inc., 2018) Sandeep, N.; Yaragatti, U.R.This paper presents a nine-level active-neutral-point-clamped (ANPC) based multilevel inverter (MLI) topology for grid-connected applications requiring only ten switches. The envisaged structure comprises two parts, namely five-level ANPC unit, and a two-level converter leg whose midpoint is used as another ac terminal. An ad hoc switching state redundancy based modulation strategy is used to ensure that the voltage across the flying capacitor is tightly balanced and is implemented using a look-up table further simplifies the control complexity. The performance and effectiveness of the proposed topology with its control scheme are validated through simulations and experimental tests. Comparison with other MLIs is included to highlight the merits of the proposed topology. From the results, it will be shown that the proposed inverter requires the least part count as compared to other topologies with the same performance and output quality. © 1982-2012 IEEE.Item A Switched-Capacitor-Based Multilevel Inverter Topology with Reduced Components(Institute of Electrical and Electronics Engineers Inc., 2018) Sandeep, N.; Yaragatti, U.R.This letter presents an improved sensorless nine-level inverter topology with reduced number of components. It is formed by cascading a three-level T-Type neutral clamped point inverter with a floating capacitor (FC) fed two-level converter unit. Additionally, two line-frequency switches are appended across the dc-link. A simple logic-form equations-based pulse width modulator is designed which is in-charge of maintaining the FC voltage at its reference value without any aid of voltage and current sensor. Thus, the complexity in control of the proposed topology is very minimal. The working principle of the proposed inverter and formulation of logic-form equations is deliberated in detail. Furthermore, experimental results obtained from the developed prototype are presented to validate feasibility and operability of the proposed topology. Finally, a comprehensive comparison with some of the recently reported inverter topologies proving the merits of the proposed topology is included. © 1986-2012 IEEE.