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 An integrated Control Approach and Power Management of Stand-alone Hybrid Wind/PV/Battery Power Generation System with Maximum Power Extraction Capability(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Sabhahit, N.S.; Gaonkar, D.N.The production of electricity from renewable energy sources like wind and photovoltaic energy has increased in recent years, due to environmental problems and the shortage of traditional energy sources. In this article we present a detailed mathematical model and a control scheme for hybrid wind and PV based DG system with battery and maximum power extraction capability for isolated mode of operation. The wind power generation system uses wind turbine (WT), a permanent magnet synchronous generator (PMSG), a three-phase diode rectifier bridge, DC/DC boost converter with maximum power point tracking (MPPT) controller. The PV generation system uses PV array, a boost converter with maximum power point tracking controller. Both sources and battery are connected to common dc bus with a dc link capacitor and supply power to load through PWM voltage source inverter. The overall control system consists of MPPT controller for both Wind and PV power system, a bi-directional DC-DC converter controller for battery energy storage management and load side inverter controller for voltage and frequency regulation. Control strategies for individual system components of the proposed system are designed with a view to achieve an acceptable level of voltage and frequency regulation while extracting the maximum power from wind and PV system. The performance of the developed hybrid system is investigated in terms of voltage and frequency regulation capability under changing wind, solar irradiation and variable load conditions.Item Power control of PV/fuel cell/supercapacitor hybrid system for stand-alone applications(International Journal of Renewable Energy Research, 2016) Sabhahit, N.S.; Gaonkar, D.N.; Nempu, P.B.This paper presents modeling and control of photovoltaic/fuel cell/supercapacitor hybrid power system for stand-alone applications. The hybrid power system uses solar photovoltaic array and fuel cell as the main sources. These sources share their power effectively to meet the load demand. The supercapacitor bank is used to supply or absorb the power during load transients. The main control system comprises of controller for maximum power tracking from photovoltaic system, a DC-DC boost converter with controller for fuel cell system for power management and inverter controller to regulate voltage and frequency. The stand-alone hybrid system aims to provide quality power supply to the consumers with a constant voltage and frequency along with proper power management using simple control techniques. The modeling and control strategies of the hybrid system are realized in MATLAB/Simulink.Item Performance analysis of a variable-speed wind and fuel cell-based hybrid distributed generation system in grid-connected mode of operation(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ayyappa, S.K.; Gaonkar, D.N.This article presents the performance study of a variable-speed wind and solid oxide fuel cell-based hybrid distributed generation system, along with the energy storage devices in the grid connected mode of operation. The developed model has a salient feature of utilizing fluctuating output power of wind systems to produce hydrogen and also to charge the ultra capacitor. The presented model in the article also uses the stored energy in the ultra capacitor to compensate for the slow response time of the fuel cell. The distributed generation systems and energy storage devices considered in this study are integrated at common distributed generation links to form the hybrid system. The hybrid system is interfaced to the grid through the three-phase voltage source inverter in this article. The detailed modeling of the individual components of the hybrid distributed generation system, along with the necessary power electronic converter control schemes, are presented. The simulation results reported in this article show the effective performance of the hybrid model to produce reliable, low-cost electricity and hydrogen from the variable wind generation system. © 2016 Taylor & Francis Group, LLC.Item Design and implementation of single phase inverter based on Cuk converter for PV system(International Journal of Renewable Energy Research, 2017) Sabhahit, N.S.; Gaonkar, D.N.; Anandh, N.; Kumar, N.S.In this paper, analysis and hardware implementation of a single phase inverter based on Cuk converter for PV system is presented. The buck-boost characteristic of such a converter promotes flexibility for both grid tied as well as standalone connections where the ac voltage is either higher than or lesser than the dc input voltage. Further Cuk based topologies have the better efficiency and voltage regulation, which is a lacking feature in a basic boost or a buck configuration. The proposed system not only offers continuous input and output current but also controlled voltage over a wider range. Hence this topology can serve as an expedient alternative converter stage for photovoltaic applications. In the proposed bidirectional two-switch Cuk converter, DSPIC30F2010 controller is used for controlling the duty ratio of switching pulses. Also, this controller generates PWM signals for the switches of single phase H-bridge inverter. The hardware results for the developed prototype of a Cuk converter based single phase inverter are presented. The developed scheme can easily be scalable to a much larger rating of the PV system.Item Design and analysis of dual output flyback converter for standalone PV/battery system(International Journal of Renewable Energy Research, 2017) Sabhahit, N.S.; Gaonkar, D.N.; Naik, A.In this paper, the cost comparison is carried out among flyback, forward and full bridge converters based upon the number of circuit components. The performance assessment in terms of efficiency of the PV array with MPPT controller using flyback and forward converter is detailed. The design and control of Photovoltaic/battery system using a flyback converter for stand-alone applications is presented. A flyback converter is used to get DC output along with an AC output for high frequency applications without employing an inverter. The PV/battery system uses photovoltaic array as the main source of power and a battery as the storage device. The energy input of the PV system is effectively utilized by adopting an MPPT technique and the storage battery is controlled to balance the load requirements using a bi-directional dc-dc converter. This system ensures that the load demand is satisfied under varying solar irradiance conditions and a constant voltage is maintained for different load conditions. The modelling and control strategy of the implemented system is realized in MATLAB/Simulink environment.Item Improved P-f/Q-V and P-V/Q-f droop controllers for parallel distributed generation inverters in AC microgrid(Elsevier Ltd, 2018) Chethan Raj, C.; Gaonkar, D.N.; Guerrero, J.M.Distributed generation inverters are generally operated in parallel with P-f/Q-V and P-V/Q-f droop control strategies. Due to mismatched resistive and inductive line impedance, power sharing and output voltage of the parallel DG inverters deviate from the reference value. This leads to instability in the microgrid system. Adding virtual resistors and virtual inductors in the control loop of droop controllers improve the power sharing and stability of operation. But, this leads to voltage drop. Therefore, an improved P-f/Q-V and P-V/Q-f droop control is proposed. Simulation results demonstrate that the proposed control and the selection of parameters enhance the output voltage of inverters. © 2018 Elsevier LtdItem Power sharing control strategy of parallel inverters in AC microgrid using improved reverse droop control(Inderscience Enterprises Ltd., 2020) Chethan Raj, D.; Gaonkar, D.N.; Guerrero, J.M.Microgrid structure is developed on the basis of distributed generation units. Microgrid distributed generation units and energy storage devices are connected through inverters interface to the point of common coupling. Microgrid system with multiple inverters, the use of conventional direct and reverse droop control method will cause uneven distribution of power, which is due to the difference between the output impedance and the line impedance of the inverter. In this paper, the traditional reverse droop control method is introduced, the power distribution of inverter output impedance is analysed, and the defects of traditional reverse droop control are pointed out. Adding virtual resistor in the control loop of reverse droop control improves the power sharing and stability of operation, but also leads to the voltage drop in microgrid. To compensate the output voltage deviation, secondary control is proposed. Simulation results show the correctness and effectiveness of the proposed control strategy. © © 2020 Inderscience Enterprises Ltd.Item HIL implementation of an islanding detection and an automatic mode switching for droop-based microgrid(Inderscience Publishers, 2022) Kulkarni, S.V.; Gaonkar, D.N.This paper presents the control schemes and performance study of parallel connected inverter based distributed generation sources (DGs) in microgrid for grid-connected and stand-alone modes of operation. This standalone mode of operation of inverter based DG system is mainly based on droop control scheme with the virtual complex impedance in the outer voltage loop. The microgrid load power is proportionally shared by the DGs according to their power ratings which features a good reliability and efficiency. Both the modes are switched automatically based on the Phase Locked Loop (PLL) phase error sin(γ – θ). This phase error is used to detect the islanding during disturbances in the system and also helps in seamless transfer between the modes. The PLL phase error response, islanding detection and mode switching are presented for various fault conditions. The hardware-in-the-loop (HIL) based platform is used to evaluate the performance of the microgrid in both the modes with islanding detection and automatic mode switching operation. © © 2022 Inderscience Enterprises Ltd.Item A Hybrid Islanding Detection Method Based on Lissajous Pattern Having Robust Performance Under Various Power Quality Scenarios(Institute of Electrical and Electronics Engineers Inc., 2023) Mondal, S.; Gayen, P.K.; Gaonkar, D.N.A fast, accurate, robust, and two-staged islanding detection technique (IDT) is proposed. It is the hybridization of second-order general integrator-frequency locked loop (SOGI-FLL), Lissajous pattern (LP), and active power absorption-cum-reactive power injection via dc-bus connected battery unit-based inverter. The LP is used to identify islanding condition on the basis of frequency variation of fundamental voltage. Here, the measured ac voltage signal is preprocessed by SOGI-FLL to obtain fundamental bus voltage under various power quality scenarios. This assures robust islanding detection by removing uncertainty, and thus, reliability is improved. The uncertainty effects due to the partial shading condition of the PV module (source-side disturbance) and weak grid-connected condition are avoided by dc-bus connected battery storage unit. Thus, it removes above-said limitations of the existing scheme. The LP-based detection within the nondetection zone is expedited due to active and reactive powers variation via controlling of the inverter and charging operation of the dc-bus connected battery unit. During the reactive power injection by solar inverter, active power is absorbed by dc-bus connected battery unit. In effect, an active power output of the inverter is reduced. Here, the reactive power injection at the reduced active power output condition of the inverter accelerates frequency variation allowing rapid islanding detection. The real-time experiments are carried out using Typhoon-HIL tools to compare the proposed method with other works reported in the literature. Improved performances under diversified scenarios are found in the proposed case. © 2007-2012 IEEE.