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Subject: search.filters.subject.Doubly fed induction generators

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    An effective reference generation scheme for DFIG with unbalanced grid voltage
    (Institute of Electrical and Electronics Engineers Inc., 2014) Asha Rani, M.A.; Nagamani, C.; Saravana Ilango, G.; Karthikeyan, A.
    This paper presents a reference current generation scheme for improved dynamic performance of a doubly fed induction generator (DFIG) subjected to unbalanced grid voltage. The power and torque oscillations induced due to the unbalance in grid voltage are minimized using additional compensatory terms in the reference currents. The focus is on estimating the reference currents and control implementation without the need for dual vector control. Real and reactive power control is implemented in the positive mbi d - q reference frame using stator flux-oriented vector control. The rotor-side converter (RSC) is controlled to enable effective reduction of oscillations in torque and active and reactive power. The dc-link voltage oscillation is minimized and the grid-side power factor is maintained unity using the grid-side converter (GSC). Unlike the previously reported techniques, the proposed scheme enables effective reduction of oscillations in torque, active, and reactive power, and the dc-link voltage, all in a single target. The performance of DFIG is investigated in consideration with the Indian Electricity Grid Code (IEGC). Numerical simulations are carried out in power system computer aided design/ electromagnetic transients including direct current (PSCAD/EMTDC) for the laboratory 3-hp DFIG test setup. The results establish that the performance of DFIG is notably enhanced with the proposed scheme. © 2014 IEEE.
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    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).
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    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 Authors
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    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.
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    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.