Faculty Publications
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Item Dynamic performance of microturbine generation system connected to a grid(2008) Gaonkar, D.N.; Pillai, G.N.; Patel, R.N.The interconnection of distribution generation systems into distribution networks has great impact on real-time system operation, control, and planning. It is widely accepted that microturbine generation (MTG) systems are currently attracting a lot of attention to meet customers' needs in the distributed power generation market. In order to investigate the performance of MTG systems, their efficient modeling is required. This article presents the dynamic model of an MTG system, suitable for grid connection to study the performance of the MTG system. The presented model uses back-to-back power electronic converter topology for grid connection, which allows the bidirectional power flow between the grid and MTG system. Thus, the need of separate starting arrangements during launching of the microturbine is avoided. The components of the system are built from the dynamics of each part with their interconnections. The dynamics of the model have been studied under various grid disturbance conditions. The converter control strategies for MTG system operation in grid-connected mode are presented in this article. This article also compares the various grid connection topologies suitable for MTG system interconnection. The simulation results show that the developed model performance is not affected by the grid disturbances considered in the study, and that it has the ability to adjust the supply as per the power requirements of the load within the MTG system rating.Item Investigation on electromagnetic transients of distributed generation systems in the microgrid(2010) Gaonkar, D.N.The increasing interconnection of distributed generation sources of diverse technologies to low-voltage grids introduces considerable complexity in its operation and control. The concept of the microgrid is emerging as a solution to this and also to take full advantage of the potential offered by distributed generation. In this article, the performance of a typical microgrid with multiple distributed generation systems in grid-connected and autonomous modes of operation has been investigated through simulation. The developed model of the microgrid consists of a converter-interfaced microturbine generation system, a synchronous-generator-based distributed generation system, and a wind power generation system with an asynchronous generator. Investigation has been carried out to study the typical electromagnetic transients of a microgrid, due to preplanned and unplanned switching events. The performance of the bidirectional grid interface topology for a microturbine generation system in a microgrid is evaluated in this work. It has been observed from the simulation results that the motoring mode operation of the microturbine generation system during starting does not cause any disturbances in the microgrid. The study also indicates that the microgrid can maintain the desired power quality at the point of common coupling. Copyright © Taylor & Francis Group, LLC.Item Single-phase seven-level grid-connected photovoltaic system with ripple correlation control maximum power point tracking(International Journal of Renewable Energy Research, 2016) Sandeep, N.; Yaragatti, R.Y.This paper puts forward a control scheme for single-phase photovoltaic (PV) fed grid connected with cascade Hbridge (CHB) inverter. A unique control strategy based on the voltage ratio is proposed and is embedded with ripple correlation control (RCC) based maximum power point tracking (MPPT) to ensure the efficient energy conversion. The control scheme employed enables the independent operation and control of individual DC link voltage, ensuring the extraction of maximum power available from each PV panel. In addition, low harmonic grid currents are generated with an arbitrary power factor. Independent control of active and reactive power is exercised by decoupled component method. Numerical simulation was performed using the MATLAB/SIMULINK platform and results for three H-bridge cells connected in series are presented to support the theoretical concepts and control scheme proposed.Item Design of backstepping controller for PV-wind hybrid system with grid-interfacing and shunt active filtering functionality(Inderscience Enterprises Ltd., 2018) Jayasankar, V.N.; Vinatha Urundady, U.This paper presents the design of a double loop controller for the grid interconnection of PV-wind hybrid system with shunt active filtering and neutral current compensation capabilities. Using Lypunov stability theory-based procedure, a backstepping controller is designed for the outer loop DC link voltage control. The adaptive nature of back stepping controller results in better dynamic performance compared to conventional controllers. Inner loop consists of instantaneous power theory-based controller for harmonic current compensation. Instantaneous power theory is modified by employing positive sinusoidal sequence regulator and self-tuning filter to improve the system performance in unbalanced and distorted grid voltage conditions. A dynamic model of the system is considered for the design. Numerical simulations are done in MATLAB/Simulink platform for different system conditions to verify the effectiveness of controller in grid interfacing of renewable sources, and the shunt active filtering. © © 2018 Inderscience Enterprises Ltd.Item Advanced control approach for shunt active power filter interfacing wind- solar hybrid renewable system to distribution grid(Engineering and Scientific Research Groups 82 Rue Baudricourt 75013 Paris, 2018) Jayasankar, V.N.; Vinatha Urundady, U.Renewable energy systems utilize the locally available energy resources and generate green energy to meet the increasing load demand. Grid integration of renewable energy systems using power electronic interfaces is the latest trend in this area of research. The non-linear loads at load centers inject current harmonics to the distribution grid at the point of common coupling and pollute the grid. The mitigation of current harmonics in the distribution grid along with the integration of renewable energy systems to the grid is the main focus of discussion in this paper. The interconnection of a hybrid solar-wind renewable energy system with the grid at the distribution level, using a voltage source inverter is presented in this paper. The inverter is controlled using the synchronous reference frame theory based control algorithm, by which the grid interfacing inverter gets additional responsibilities of shunt active power filter. Grid interfacing system consists of a 3-phase, 4-leg voltage source inverter, a dc-link capacitor and a hysteresis current controller. A self-tuning filter is designed and used in the control system for effective elimination of current harmonics. Simulation results are presented with variation in the renewable energy generation and variation in load for validating the practical application of the proposed system. All simulations are done in MATLAB-Simulink platform. The performance of 4-leg inverter in exchanging real power from renewable sources to grid along with compensating current harmonics, under balanced and unbalanced grid voltage conditions are analyzed. © JES 2018.Item A Precise Switching Frequency Formulation of Hysteresis-Controlled Grid-Connected Inverters Considering Nonlinear Ripple Current(Institute of Electrical and Electronics Engineers Inc., 2022) Damodaran, R.; Venkatesa Perumal, B.V.Hysteresis current control (HCC) is one of the most simple and rapid modulation techniques for multilevel grid-connected inverters (MGCIs). It controls the output current by limiting its ripple within fixed hysteresis limits. This results in a varying switching frequency, which is not known implicitly. The knowledge of switching frequency is essential for filter design, device selection, and loss calculations of the MGCI. The existing frequency estimations for HCC assume linear ripple current considering high-frequency operation. This assumption is invalid for the range of low frequencies. This leads to inaccurate estimation of switching frequency, which can have a considerable effect on system design. In this article, a more precise and generalized expression to estimate the switching frequency of the MGCI is obtained. The improvement in accuracy is demonstrated with an example of second-order filter design. The effect of change in hysteresis limits and input voltage on the switching frequency is analyzed to determine the operating point for accurate system design. Simulation and experimental results are found to be in good agreement with the theoretical claims. © 1982-2012 IEEE.Item A sorted modified multi-reference PWM technique for solar PV panel companion grid-tied inverters(Springer Science and Business Media Deutschland GmbH, 2025) Maheswari, G.; Manjunatha Sharma, K.M.; Prabhakaran, P.Pulse Width Modulation (PWM) techniques are increasingly vital in solar energy-driven grid-tied companion inverters, significantly enhancing power quality. This paper proposes the Sorted Modified Multireference Pulse Width Modulation (SMMR PWM) technique. The SMMR PWM with a Maximum PowerPoint Tracking (MPPT) control strategy is implemented in a Solar PV Panel Companion Grid-Tied Inverter (SPPCGTI) system featuring single-stage power conversion. In the SPPCGTI system, each inverter's output voltage adopts a quasi-square waveform, where the pulse width correlates with the power generated by the associated solar PV panel. By employing the SMMR PWM technique with the MPPT control strategy in the SPPCGTI system, precise MPPT for each PV panel is achieved, irrespective of uniform or non-uniform irradiation conditions. Additionally, this technique reduces Total Harmonic Distortion (THD) in the AC grid current of the solar PV panel companion inverter (SPPCI) while simultaneously enhancing MPPT efficiency, inverter efficiency [inverter efficiency is less than the Sorted-Staircase Modulation (SSCM) and more than the Sorted PWM (SoPWM)], and reducing settling time compared to the existing techniques like SSCM and SoPWM. The SPPCGTI with the integrated SMMR PWM technique, MPPT algorithm, and current controller is modeled and simulated in MATLAB/Simulink. Experimental testing affirms the outstanding performance of the proposed SMMR PWM technique. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Item Novel sorted PWM strategy and control for photovoltaic-based grid-connected cascaded H-bridge inverters(Springer, 2025) Maheswari, G.; Manjunatha Sharma, K.M.; Prabhakaran, P.This paper proposes a novel sorted level-shifted U-shaped carrier-based pulse width modulation (SLSUC PWM) strategy combined with an input power control approach for a 13-level cascaded H-bridge multi-level inverter designed for grid connection, specifically tailored for photovoltaic (PV) systems, which avoids a double-stage power conversion configuration. In this methodology, every inverter generates a quasi-square output voltage waveform with a width that is intricately linked to the output power of its corresponding PV panel. The application of this SLSUC pulse width modulation technique with input power control in a solar energy-based 13-level grid-tied inverter facilitates precise maximum power point (MPP) tracking for each of the PV panels under uniform and non-uniform irradiation conditions and ensures the consistent maintenance of capacitor voltage balance. Moreover, this novel SLSUC PWM method for 13-level inverters offers a range of benefits, including a low total harmonic distortion (THD) in the output voltage of the multi-level inverter and higher inverter and MPPT efficiencies over the existing PWM techniques. To verify the efficacy of the proposed control method over existing techniques, a PV-based grid-connected multi-level inverter with the proposed control strategy undergoes modeling and simulation using MATLAB/Simulink. Then, experimental hardware-in-the-loop (EHIL) testing is conducted to confirm and evaluate its effectiveness. © The Author(s) under exclusive licence to The Korean Institute of Power Electronics 2024.Item A Novel Seven-Level Triple-Boost Inverter for Grid-Integrated Photovoltaic Systems(Springer, 2025) Maheswari, G.; Manjunatha Sharma, K.M.; P, P.Transformer-less switched-capacitor-based multilevel inverters (TL-SCMLIs) are increasingly preferred for photovoltaic (PV) applications due to their voltage boosting capability, high efficiency, reduced dv/dt stress, and lower cost. However, existing SC-based multi-level inverters often require more components, suffer from leakage currents, have lower boost gain capability, have higher PU total standing voltage, and exhibit lower efficiency. To address these challenges, this paper proposes a novel seven-level switched-capacitor (SC)-based TL-MLI with higher voltage boosting gain and a common ground (CG) configuration for improved performance in grid-tied PV applications. A proportional-integral (PI) controller is designed for the grid-tied seven-level PV inverter, and its performance is evaluated through simulation studies and hardware-in-the-loop (HIL) experimental verification. Finally, a detailed comparative analysis with existing multi-level inverters highlights the proposed seven-level inverter’s advantages, including leakage current reduction, high boost gain, lower cost, lower PU total standing voltage, lower voltage stress, lower peak inverse voltage, and improved efficiency. The total harmonic distortion (THD) of the grid current is less than 5% for the proposed grid-tied seven-level inverter. © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd. 2025.Item Performance Evaluation and Machine Learning Analysis of 3 kW Grid-Connected Bifacial Solar Photovoltaic Systems(Springer, 2025) Shiva Kumar, B.S.; Kunar, B.M.; Murthy, C.S.N.Rooftop solar panels with dual functions are a promising sustainable energy source given the world’s rapid urbanization, particularly in densely populated nations like India. Numerous studies have shown how well the System Advisory Model (SAM) performs when estimating the energy yield of bifacial solar photovoltaic (BSPV) systems. This study uses a popular photovoltaic design software to compare the output of a 3 kW grid-connected BSPV system. The SAM simulation forecasts a production of 4864.5 kWh, whereas the empirical data shows that the system’s yearly energy output is 4321.7 kWh. The operational plant’s performance ratio is about 81.6%, which closely agrees with the 81.2% that SAM projected. Further, the relationship between various input parameters and power output of a BSPV generated from SAM simulation results was investigated using machine learning (ML) models. Among the ML models tested, the linear regression (LR) model delivered the best performance for a 3 kW BSPV system in a specific location. © The Institution of Engineers (India) 2025.