Faculty Publications
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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 An effective standalone hybrid wind-photovoltaic water pumping system with reduced power converter count(John Wiley and Sons Ltd, 2021) Angadi, S.; Yaragatti, U.R.; Yellasiri, Y.; Raju, A.B.This article proposes a standalone hybrid wind-photovoltaic (PV) water pumping system (WPS) with minimal power electronics interface, simple composite control, and optimal energy management strategy (EMS) for effective utilization of both renewable sources. The proposed system consists of classic Perturb and Observe (P&O) algorithm applied to the boost converter of the solar PV system and voltage regulation algorithm/hill-climbing MPPT algorithm with zero steady-state oscillation (ZSSO) applied to bidirectional voltage source converter (VSC) of wind energy conversion systems (WECS) for optimal power extraction at all times. The constant voltage to frequency (V/F) ratio is ensured at the point of common coupling (PCC) for the entire operating range to avoid saturation in the self-excited induction generator (SEIG) and the induction motor (IM) pump. The energy management strategy is devised to effectively harness renewable energy from both sources while ensuring the DC-link voltage stability. The system forms compelling proposition, given the least converter count to integrate solar-PV and wind energy employing easy to implement control algorithms with optimal energy extraction. The results of simulation and experimental studies on the proposed system reveal the effectiveness of the composite controller in terms of energy utilization, constant flux operation, and power balance for the entire operating range. Additionally, system exhibits acceptable dynamic and steady-state behavior against variations in wind velocity, solar irradiation, and load. © 2021 John Wiley & Sons Ltd.Item Design and implementation of constant flux controller for VSI assisted SEIG feeding induction motor pump(Inderscience Publishers, 2022) Angadi, S.; Yaragatti, U.R.; Yellasiri, Y.; Raju, A.B.In small scale, stand-alone, wind-power generation employing self excited induction generator (SEIG), water pumping using an induction motor is a typical application. In this paper, a simple voltage regulation scheme for the constant flux operation of the inverter assisted SEIG feeding three-phase induction motor pump is presented. The behaviour of DC-link voltage, frequency, amplitude modulation index (ma) and the shaft speed for load and speed perturbations are discussed in detail. Also, the overall active and reactive power flow for constant flux operation at the point of common coupling (PCC) is analysed. The proposed work presents a simple and reliable controller for SEIG-based stand-alone system for frequency-dependent loads using only a DC-link voltage sensor. Detailed system simulations are performed using Matlab/Simulink and the results of a laboratory prototype are presented to validate the theoretical analysis and practical operability of the proposed system. © 2022 Inderscience Publishers. All rights reserved.Item Speed sensorless maximum power point tracking technique for SEIG-based wind energy conversion system feeding induction motor pump(Springer Science and Business Media Deutschland GmbH, 2022) Angadi, S.; Yargatti, U.R.; Yellasiri, Y.; Raju, A.B.This paper proposes a hill-climbing maximum power point tracking (MPPT) algorithm for a stand-alone self-excited induction generator (SEIG)-based wind energy conversion system (WECS) feeding an Induction Motor (IM) pump. The proposition involves a single voltage source converter (VSC) for power conditioning and MPPT. Secondly, the proposed MPPT algorithm is one of its kind, employing a feed-forward hill-climbing algorithm with the operating frequency of the VSC as a control variable, thus improving the overall system stability. In addition, the algorithm uses only current and voltage sensors, making it speed sensorless and comprehensive. Besides effective MPPT, the constant flux operation of the SEIG and the IM pump are ensured for the entire operating range. The effective operation and control of the proposed algorithm is successfully demonstrated against wind velocity and load variations using simulation and experimental results. The proposition forms robust, low-complex and economic solution for MPPT of WECS for deployment in remotely located stand-alone applications. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Grid-Connected DFIG Driven Wind System for Low Voltage Ride Through Enhancement using Neural Predictive Controller(Springer, 2022) Hiremath, R.; Moger, T.Doubly Fed Induction Generators (DFIGs) are exposed to severe grid faults. In such cases, Low Voltage Ride Through (LVRT) enhances the DFIG’s performance under fault conditions. This paper investigates the LVRT enhancement of the DFIG system under grid disturbance. The paper proposes the Neural Predictive (NP) controller for the DFIG based Wind Turbine (WT) generator during grid faults. This controller operates with the Levenberg-Marquardt (LM) algorithm for its fast convergence. The algorithm based Neural Predictive (NP) controller is operated for large signal stability. The proposed controller has the benefit of reducing the peak values and uncertainties, which are raised for the system parameters during grid faults. Further, the proposed controller outcome is compared with existing controllers in the literature such as PI, PID, Feed-Forward Neural Network (FNN), and 2nd order Sliding Mode Controller (SOSMC) with the help of MATLAB/SIMULINK. The Hardware-In-Loop (HIL) is used to validate the simulation results, which have been performed on the OPAL-RT setup. According to the results that are obtained in this study, the proposed controller improved the LVRT performance of the DFIG-Wind Turbine (WT) system while operating under dynamic conditions. © 2022, The Institution of Engineers (India).Item Modified Super Twisting algorithm based sliding mode control for LVRT enhancement of DFIG driven wind system(Elsevier Ltd, 2022) Hiremath, R.; Moger, T.The grid-connected Doubly Fed Induction Generator (DFIG) system is exposed to severe grid faults. The DFIG is sensitive to grid disturbances, which lead to consideration in the controller design. This paper proposed the Modified Super Twisting (MST) algorithm for the Low Voltage Ride Through (LVRT) enhancement under voltage sag condition. This proposed algorithm is implemented using the 2nd Order Sliding Mode (SOSM) to control the DFIG based wind generator. The higher-order switching functions are introduced in the SOSM for sliding surface control. Moreover, the Lyapunov analysis for the MST algorithm brings down the chattering amplitude. The advantages of the proposed algorithm are that it reduces the system uncertainties, chattering effect and improves the settling period of the system parameters. The performance of the proposed algorithm is compared with existing algorithms in the literature with the help of MATLAB/SIMULINK. The Hardware-In-Loop (HIL) is used to validate the simulation results, which have been performed on the OPAL-RT setup. In addition, the proposed algorithm is also tested on an equivalent model of the practical Wind Farm (WF). Based on the studies, it is found that the proposed algorithm enhanced the LVRT performance of the single Wind Turbine (WT)-DFIG system as well as the practical WF under transient conditions. © 2022 The AuthorsItem Improving the DC-Link Voltage of DFIG Driven Wind System Using Modified Sliding Mode Control(River Publishers, 2023) Hiremath, R.; Moger, T.The grid-connected doubly fed induction generator (DFIG) driven wind turbine (WT) system encounters voltage fluctuations due to severe grid faults. The rise in DC-link voltage imbalances the system under voltage sag condition. The system’s protection should ensure that the WT generator meets the grid requirements through a low voltage ride through (LVRT) technique. This paper proposed the modified 2nd order sliding mode (MSOSM) control with gain added super twisting algorithm (GAST) for LVRT enhancement under voltage sag. This controller adds the low positive gains to the switching functions of the super twisting (ST) algorithm. As a result, it maintains the proper variation margins and constant DC-link voltage of the WT-DFIG system under grid fault. The MSOSM controller suppresses the chattering effect, achieves better zero convergence, and eliminates the coordinate transformations. Moreover, the performance of the proposed controller is compared with existing controllers in the literature with the help of MATLAB/SIMULINK. The hardware-in-loop (HIL) validates these simulation results performed on the OPAL-RT setup. Based on the studies, it is found that the proposed controller enhances the performance of the WT-DFIG system under transient conditions. © 2023 River Publishers.Item Computation of steady-state operating conditions of a DFIG-based wind energy conversion system considering losses(Springer Science and Business Media Deutschland GmbH, 2023) Karthik, D.R.; Manjarekar, N.S.; Kotian, S.M.In this paper, steady-state operating conditions of a doubly fed induction generator (DFIG) are computed considering losses of grid-side (GS) filter. Two different cases are studied for steady-state initialization of the DFIG-based wind turbine systems (WTS). In the first case, active power (P) and reactive power (Q) at DFIG terminals are assumed to be known. In the other case wind speed (Vw), Q is assumed to be known. Apart from considering losses of the DFIG and GS filter, both the cases also consider the non-unity power factor operation of the grid side converter (GSC). For the first case, steady-state operating conditions are calculated by iterative method as well as by non-iterative method. For the second case, iterative method is used to calculate steady-state operating conditions. Calculation of steady-state values of other subsystems of DFIG-based WTS like drive train, controller and network is also shown. The initial values calculated are validated and compared by performing modal analysis and time-domain simulations. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.