Faculty Publications

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    STFT Filter Bank Based Islanding Detection Technique
    (Institute of Electrical and Electronics Engineers Inc., 2023) Pinto, J.A.; Vittal, K.P.
    Depleting coal reserves and increasing carbon emissions have propelled the use of renewable energy sources to generate electricity. Microgrids have been recognised as one of the solutions to provide continuity of power to critical loads even during natural disasters, as they can connect or disconnect from the main grid. The presence or absence of the grid is critical to the operation of the various inverter-based resources and load management in the Microgrid. Various active and passive methods have been proposed by researchers to detect islanding. This paper focuses on detecting the islanding condition based on the filter bank approach of Short Time Fourier Transform. The voltage at the interface of distributed generation was sensed and the amplitude of a particular frequency component was estimated using the filter bank approach. The estimated amplitude was then checked against a set threshold to detect islanding. The proposed islanding detection technique was tested and was found effective on a sample Microgrid for conditions like normal operation, operation during faults and operation during turning ON and OFF loads and sources. © 2023 IEEE.
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    Renewable Power Integration for Electric Vehicle Charging System: A Review
    (Institute of Electrical and Electronics Engineers Inc., 2025) Nirala, P.K.; Barik, A.K.; Bhushan, R.; Jagtap, K.M.; Raushan, R.
    This review paper accentuates on the conceivable integration of renewable based generations to the charging stations of Electric Vehicles (EVs) towards restraining the carbon emissions. The intensifying global demand for EVs in recent days puts stress on conventional grid with existing infrastructure, which could be relaxed by integration of renewable based power generations with ecological balance. The importance and feasibility of renewable integrations to charge the EVs are reviewed in this paper and suitable applications are reported to develop charging infrastructures for EVs. The importance of vehicle to grid (V2G) concept is also reviewed to facilitate ancillary support to future grid integrated with renewables. © 2025 IEEE.
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    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.
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    Bi-directional power flow control with improved power quality using intelligent controller for AC-DC coupled hybrid micro-grid system
    (Inderscience Publishers, 2021) Nagaraj, C.; Manjunatha Sharma, K.
    Grid connected renewable sources are affected by harmonic distortion due to non-linear power electronics interfaces. Depending upon the nature of the load, many conversion stages are incorporated in the micro-grid which leads to increase in the losses. Therefore, in this paper, the AC-DC coupled hybrid micro-grid system is presented in which AC renewable sources and AC loads are connected to AC sub-grid and DC renewable sources and DC loads are connected to DC sub-grid. The shunt active power filter based 3? 4-leg bi-directional intermediate converter using d-q load current technique is proposed to achieve the power flow between AC and DC sub-grids. The MATLAB simulation is carried out, and the performance of the proposed system is analysed using the d-q load current technique based fuzzy logic and PI controller. The obtained results demonstrate that the overall system performance is improved with the d-q load current technique based fuzzy logic controller. © © 2021 Inderscience Enterprises Ltd.
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    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.
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    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.
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    Model predictive controlled three-level bidirectional converter with voltage balancing capability for setting up EV fast charging stations in bipolar DC microgrid
    (Springer Science and Business Media Deutschland GmbH, 2022) Nisha, K.S.; Gaonkar, D.N.
    Transportation electrification and charging infrastructure development has to gain momentum in order to go hand-in-hand with the fast advances in the electric vehicle technology. Setting up dc fast charging stations connected to bipolar DC microgrid is a great viable option to utilize the distributed energy resources for transportation electrification. It also helps to eliminate power quality issues in ac grid that may arise due to the unpredictable charging/discharging behaviour of EVs. This paper focuses on model predictive control of a three-level bidirectional dc–dc converter suitable for interconnecting bipolar DC microgrid with dc fast charging stations or battery energy storage. State space analysis is done, and discrete model is developed. Simulation of the proposed system with model predictive control is done in Simulink MATLAB. Real-time hardware in loop performance is tested and verified using Typhoon HIL 402. The proposed converter is able to mitigate the voltage unbalance issues arising in the bipolar DC microgrid and is capable of controlling bidirectional power flow, hence suitable for V2G/G2Voperation. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Incremental transient power-based protection scheme for a DC microgrid
    (Springer Science and Business Media Deutschland GmbH, 2022) Joshua, A.M.; Vittal, K.P.
    A key step in the realisation of DC microgrids is the development of robust protection schemes. Bidirectional power flow in ring-type configurations makes protection design too complicated. This paper presents an algorithm for selective fault location and isolation of faulty parts in the transient stage itself. At the onset of a fault, the proposed scheme computes incremental transient power (Δ P) from initial changes in voltage and current. The sign of Δ P captured by different IEDs is compared to determine the fault location. Though the scheme is designed for the unit protection of feeders, it is also capable of locating and isolating external faults accurately. A backup scheme using local measurements is provided, in case of communication failure. The schemes are simulated using extensive simulations in MATLAB/SIMULINK platform. The results confirm that the proposed protection design operates within a few milliseconds and is highly selective and stable. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Optimal operation of multi-source electric vehicle connected microgrid using metaheuristic algorithm
    (Elsevier Ltd, 2022) Sabhahit, N.S.; Jadoun, V.K.; Gaonkar, D.N.; Shrivastava, A.; Kanwar, N.; Nandini, K.K.
    In this paper, a multi-source microgrid (MG) has been considered which inducts power from solar photovoltaic (PV), wind turbine, pumped hydro storage system (PHSS) and diesel generator (DG). A problem formulation is proposed on a multi-source MG considering an electric vehicle (EV) as source and load demand. A modified operation strategy is proposed to achieve the lowest possible fuel usage of DG and to optimize the operation of multi-sources used in the MG. When the sum of PV, wind power production and EV discharge is less than the load requirement, the required deficit power should be delivered by DG and PHS. This work considers PV and wind as the primary energy supplying sources, while DG, EV and PHS as the additional energy suppliers with EV and PHS as energy storage systems. By properly coordinating EVs, they can become a major contributor to the successful execution of the MG concept. In this work, a modified charging/discharging algorithm is presented to check the effect of EVs to supply a portion of peak loads with PHS to reduce the fuel consumption of DG in three diverse modes of operation. A modified whale optimization algorithm (WOA) and teaching learning-based optimization (TLBO) are applied to effectively solve this proposed complex problem using the MATLAB platform. The optimum solutions obtained after different independent trials by both the techniques are compared with the latest published techniques. It can be observed that modified WOA performs better than TLBO and other recently published methods on the base case and proposed multi-source MG case in three diverse modes of operation. The outcomes of the simulation confirm the effectiveness of modified WOA in reducing fuel consumption. © 2022 Elsevier Ltd
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    Operation and control of multiple electric vehicle load profiles in bipolar microgrid with photovoltaic and battery energy systems
    (Elsevier Ltd, 2023) Nisha, K.S.; Gaonkar, D.N.; Sabhahit, N.S.
    Charging of electric vehicles is going to be a major electrical load in the near future, as more and more population shift to electric auto-motives from conventional internal combusted engine-powered vehicles. Integration of electric vehicle charging stations (EVCS) might even burden the existing grid to a point of collapse or grid failure. Establishing charging stations interfaced with bipolar DC microgrids along the roads and highways is the most realistic and feasible solution to avoid the overburdening of the existing power system. The bipolar DC microgrid is a far better microgrid structure than the unipolar microgrid structure in many aspects like reliability, flexibility, and controllability. It can provide multiple voltage level interfaces according to the load demands, which is very apt for different charging levels of electric vehicles (EVs). Operation of multiple sources and multiple loads connected to bipolar DC microgrid will affect DC voltage regulation, capacitance-voltage balancing, and overall stable operation of the grid. In order to mitigate these power quality problems arising in multi-node bipolar DC microgrids, a decentralized model predictive control is proposed in this paper. EV charging load profiles are modeled and developed by considering standard driving cycles, state of charge, and power demand of multiple vehicles to study the effect of unpredictable varying EV loads in the bipolar DC microgrid. EVCS thus modeled are connected to solar photovoltaic-battery energy storage fed bipolar DC microgrid with three-level/bipolar converters and analyzed under dynamic conditions for capacitance–voltage unbalance mitigation, voltage regulation, and the stability of operation with model predictive control. Simulation studies are carried out in MATLAB/Simulink to verify the effectiveness of the system. © 2022 Elsevier Ltd