Faculty Publications
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Item Operation and control of a microgrid in isolated mode with multiple distributed generation systems(Institute of Electrical and Electronics Engineers Inc., 2018) Kulkarni, S.V.; Gaonkar, D.N.In this paper performance study of the microgrid in isolated mode of operation is presented using the real time hardware in loop tool. The droop control and virtual complex impedance concept has been implemented for accurate load sharing among the inverter based DG system in the microgrid. The control strategy for operation of inverters in autonomous mode of operation is given. The implementation detail of the microgrid with voltage source inverter based DG systems is given in this paper. The real time performance verification of the implemented microgrid is presented. The performance results of the microgrid reported in this paper indicate that the DG systems are able to share the load in proportion to their ratings. Also, the results show that the voltage and frequency of the microgrid are maintained without any transients. © 2017 IEEE.Item Investigation of PLLs for Distributed Generation Systems in the Grid-connected Mode of Operation(Institute of Electrical and Electronics Engineers Inc., 2020) Kulkarni, S.V.; Gaonkar, D.N.The distributed generation systems (DGs) include the phase-locked loop (PLL) controller when incorporated into the grid for synchronization. In this paper, we presented the three foremost PLL based grid synchronization methods, and the examination of PLLs for parallel-connected DGs when they integrated into the grid is introduced. Specifically, the exhibition of the PLLs under different conditions is investigated. The PLL strategy for grid-integrated parallel-connected multiple DGs is implemented in Typhoon hardware in the loop software platform and verified with Typhoon 402 hardware equipment. The outcomes obviously show the viability of the examined PLL controllers in grid-integrated operation for the multiple parallel-connected DGs. © 2020 IEEE.Item Comprehensive Strategy for Power Quality Improvement of Inverter Based Distributed Generation Systems(Springer Science and Business Media Deutschland GmbH, 2022) Kulkarni, S.V.; Gatade, S.; Samanvita, N.; Gaonkar, D.N.In the present scenario, the continuously increasing demand for electrical energy and the ardent scarcity of renewable energy sources leads to the need for the distributed generation (DG) systems. The DGs with nonlinear and unbalanced loads on the output lead to the power quality issues. One of the main causes of harmonic distortion is the nonlinear loads, which can be harmful in the presence of unbalanced and harmonic power supplies, i.e., power electronic converters. In this study, the inverter-based DG sources for power quality improvement is studied. The paper aims at evaluating the impact of non-linear loads and also aims at improving the power quality using proposed unified power quality conditioner (UPQC) in inverter based DGs. The studied system model is simulated in the MATLAB/SIMULINK environment, and the simulation result shows the better performance under the power quality disturbances. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Hardware Co-simulation of Pulse Amplitude Modulation Controlled BLDC Motor(Institute of Electrical and Electronics Engineers Inc., 2022) Prabhu, P.; Kulkarni, S.V.; Urundady, V.This paper describes the validation of a Field Programmable Gate Array (FPGA)-based controller for Brushless Direct Current (BLDC) motor drive using the hardware co-simulation feature enabled in the Xilinx System Generator (XSG) design tool. To control the speed of the BLDC motor, the proposed BLDC drive uses PAM control of the Voltage Source Inverter (VSI). The PAM control reduces switching losses by allowing the VSI to operate at the frequency determined by synchronous speed. At the front end, a bridgeless SEPIC provides a wide range of DC voltage to the VSI input. When compared to the topology with two separate inductors, the Bridgeless SEPIC coupled inductors reduce the overall component count and the self-inductance required. The converter is designed to operate in Discontinuous Conduction Mode (DCM) by applying a simple voltage follower approach to a SEPIC converter to achieve inherent input current shaping over a wide speed range. The precise reference voltage for the DC link is calculated in the outer speed control loop. The proposed BLDC motor drive is modeled using the XSG design tool, and the controller is implemented in FPGA. Hardware co-simulation is used to evaluate the controller's performance under dynamic conditions such as step changes in reference speed and supply voltage. © 2022 IEEE.Item An investigation of PLL synchronization techniques for distributed generation sources in the grid-connected mode of operation(Elsevier Ltd, 2023) Kulkarni, S.V.; Gaonkar, D.N.In recent years, the proliferation of grid-connected microgrid systems has witnessed a remarkable surge, driven by the need to enhance the availability and reliability of renewable energy sources during peak demand periods. By reducing reliance on fossil fuels, these systems offer promising avenues for sustainable energy integration. To ensure seamless synchronization of renewable energy sources with the grid, Phase-Locked Loop (PLL) controllers have emerged as a key solution. However, the information available about these PLLs is limited. In this paper, the analysis, design, and comparison of PLLs, along with the exploration of a recently developed PLL synchronization method. Specifically, we evaluate the performance of prominent PLL techniques, including PSRF-PLL, SOGI-PLL, DSOGI-PLL, E-PLL, and IPT-PLL, under diverse test scenarios such as voltage sag, swell, unbalance, and harmonics. To assess their effectiveness, hardware-in-loop virtual and real-time test-beds are employed, enabling rigorous examination of the PLL techniques for grid synchronization. The reported results demonstrate the phase tracking capability when operating in grid-connected mode. Finally, conclusions are drawn from studies conducted in the electrical grid network's healthy and unhealthy environments. © 2023 Elsevier B.V.Item Operation of the Microgrid with Improved Droop Control Strategy and an Effective Islanding Detection Technique for Automatic Mode Switching(Taylor and Francis Ltd., 2021) Kulkarni, S.V.; Gaonkar, D.N.; Guerrero, J.M.This paper presents the islanding detection and automatic mode switching for inverter-based distributed generation sources (DGs) in the microgrid with an improved droop controlled scheme. The modification in the conventional droop among the DGs is contrived to share the load proportionate to their power capacity. And to reduce the circulating currents and to improve reactive power-sharing the virtual impedance is implemented for the microgrid in the stand-alone mode operation. Also, the modified Park synchronous reference frame based phase-locked loop (PSRF-PLL) is implemented for the operation of the microgrid in the grid-connected mode. The islanding detection and automatic mode switching depend on the PSRF-PLL, which uses the input obtained from the stationary reference frame. The proposed PLL implemented in this work is simple in construction and keeps the phase locking error to near zero, thus leading to proper locking with reduced complexity. The control scheme's performance in the microgrid is validated using the real time hardware in the loop platform. The performance of PSRF-PLL based islanding detection scheme is analyzed considering the various grid disturbances, and the comparative study with the other PLL based scheme is also presented in this paper to show the improved performance of the proposed PSRF-PLL scheme. © 2021 Taylor & Francis Group, LLC.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.Item A Novel Islanding Detection Technique Based on Piezoelectric Sensors for Grid-Integrated DG Systems(Taylor and Francis Ltd., 2023) Kulkarni, S.V.; Hegde, V.; Gaonkar, D.N.This paper presents the novel islanding detection technique that depends on the piezoelectric sensors for distributed generation sources (DGs) in the grid-integrated operation mode. The islanding detection method employs a piezoelectric sensor for the detection of the frequency variations during grid disruptions. The designed diaphragm-based sensor has a natural frequency as that of the fundamental frequency of the system frequency signal. Any further deviations from the natural frequency due to the disturbances will be sensed by the sensor and a control signal is being sent to the associated circuit breaker for suitable action. The sensor structure is modeled using the finite element method and implemented in the Phase-Locked Loop (PLL) of the grid-integrated DGs. The proposed circular diaphragm-based sensor structure will have the bandwidth in the range of natural frequency with the tolerance rate of ±1% and uses the input signal received from the PLL controller outer loop. The proposed islanding detection technique’s performance and reliability for grid-integrated DG are validated using the real-time hardware in the loop test-bed platform. The HIL virtual simulated responses show that the method can be proposed effectively for islanding detection in the event of frequency variations in the grid-integrated DG systems. © 2023 IETE.