Faculty Publications
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Item Multiple inverters operated in parallel for proportional load sharing in microgrid(Institute of Advanced Engineering and Science info@iaesjournal.com, 2017) Chethan Raj, D.; Gaonkar, D.N.The new energy source utilization and development, gradual rise of distributed power grid miniaturization, intelligence, control has become a trend. In order to make microgrid reliable and efficiently run, control technology of microgrid has become a top priority and an inverter as microgrid basic unit, its control has become the most important part in microgrid. In this paper, three inverters are operated in parallel using an P-V/Q-F droop control is investigated. Mathematical model of three phase inverter with LC filter is derived, which is based on the voltage and current dual control loop. Parallel control strategy based on P-V/Q-F droop control, does not require a real time communications between the inverters and more suitable for microgrid applications. To verify the feasibility and validity of the droop control scheme, simulation is done in Matlab/Simulink and results indicate droop control has significant effect on power sharing and balancing the voltage magnitude, frequency. © 2017 Institute of Advanced Engineering and Science. All rights reserved.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 Improved droop control strategy for parallel connected power electronic converter based distributed generation sources in an Islanded Microgrid(Elsevier Ltd, 2021) Kulkarni, S.V.; Gaonkar, D.N.The control and protection are critically essential to facilitate the stable operation of an island microgrid. To accomplish the exact power sharing in an islanded AC microgrid, the frequency and the voltage restoration need to be sustained. In this regard, a robust control strategy pooling an improved droop with a virtual impedance control based droop control for power sharing with f/V restoration is proposed in this article. The proposed droop controller state-space small signal modeling and an investigation for the total microgrid system are presented in this article. Meanwhile, the robustness of the strategy is escalated for a step change in the system power loads. The overall controller performance has been tested in the hardware-in-loop (HIL) test-bed. © 2021 Elsevier B.V.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.