• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.6
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• pp.325-336
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• 2006

This paper deals with the dynamic analysis of variable speed wind power systems with doubly-fed induction generators (DFIG). First, the mathematical modeling of wind farm which consists of turbine rotor, DFIG, rotor side and grid side converter and control systems is presented. In particular, the equation for dynamic modeling of the DFIG and the AC/DC/AC converter is expressed as dq reference frame. And then, on the basis of mathematical modeling for each component of wind farm, dynamic simulation algorithms for speed and pitch angle control of wind turbine and generated active and reactive power control of the DFIG and the AC/DC/AC converter are established. Finally, Using the MATLAB/SIMULINK, this paper presents dynamic simulation model for 6MW wind power generation systems with the DFIG considering distribution systems and performs the dynamic analysis of wind power systems in steady state. Moreover, this paper also presents the dynamic performance for the case when the voltage sag in grid source and phase fault in bus are occurred.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.211-216
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• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.466-472
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• 2013

The paper presents a novel DC grid connection topology and control strategy for doubly-fed induction generator (DFIG) based wind power generation system. In order to achieve the wind power conversion, the stator side converter and the rotor side converter is used to implement the DFIG control based on the indirect air-gap flux orientation, and a DC/DC converter is used for the DFIG system to DC grid connection. The maximum power point tracking and DC voltage droop control can also be implemented for the proposed DFIG system. Finally, a 4-terminal DFIG-based multi-terminal DC grid system is developed by Matlab to validate the availability of the proposed system and control strategy.

• Journal of Power Electronics
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• v.17 no.3
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• pp.733-743
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• 2017

This paper develops a coordinated control strategy of the doubly fed induction generator (DFIG) system based on repetitive control (RC) under generalized harmonic grid voltage conditions. The proposed RC strategy in the rotor side converter (RSC) is capable of ensuring smooth DFIG electromagnetic torque that will enable the possible safe functioning of the mechanical components, such as gear box and bearing. Moreover, the proposed RC strategy in the grid side converter (GSC) aims to achieve sinusoidal overall currents of the DFIG system injected into the network to guarantee satisfactory power quality. The dc-link voltage fluctuation under the proposed control target is theoretically analyzed. Influence of limited converter capacity on the controllable area has also been studied. A laboratory test platform has been constructed, and the experimental results validate the availability of the proposed RC strategy for the DFIG system under generalized harmonic grid voltage conditions.

• Advances in Computational Design
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• v.8 no.3
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• pp.237-253
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• 2023

Torque ripple content and variable switching frequency operation of conventional direct torque control (DTC) are reduced by the integration of space vector modulation (SVM) into DTC. Integration of space vector modulation to conventional direct torque control known as SVM-DTC. It had been more frequently used method in renewable energy and machine drive systems. In this paper, SVM-DTC is used to control the rotor side converter (RSC) of a wind driven doubly-fed induction generator (DFIG) because of its advantages such as reduction of torque ripples and constant switching frequency operation. However, flux and torque ripples are still dominant due to distorted current waveforms at different operations of the wind turbine. Therefore, to smoothen the torque profile a Neural Network Controller (NNC) based SVM-DTC has been proposed by replacing the PI controller in the speed control loop of the wind turbine controller. Also, stability analysis and simulation study of DFIG using process reaction curve method (RRCM) are presented. Validation of simulation study in MATLAB/SIMULINK environment of proposed wind driven DFIG system has been performed by laboratory developed prototype model. The proposed NNC based SVM-DTC yields superior torque response and ripple reduction compared to other methods.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.371-378
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• 2010

Most modern wind turbines employ a doubly-fed induction generator (DFIG) system due to its many advantages, such as variable speed operation, relatively high efficiency, and small converter size. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. We propose a protection algorithm for a DFIG based on a d-q equivalent circuit in the time domain. In the DFIG, the voltages and currents of the rotor side and the stator side are available. The proposed algorithm estimates the instantaneous induced voltages of magnetizing inductance using those voltages and currents from both the stator and the rotor sides. If the difference between the two estimated induced voltages exceeds the threshold, the proposed algorithm detects an internal fault. The performance of the proposed algorithm is verified under various operating and fault conditions using a PSCAD/EMTDC simulator.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.494_495
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• 2009

This paper presents a study of DFIG wind power generation system for real-time simulation. For real-time simulation, the real-time digital simulator (RTDS) and its user friendly interface simulation software (RSCAD) are used. 2.2MW grid-connected variable speed DFIG wind power generation system is modeled and analyzed in this study. Stator-flux oriented vector control scheme is applied to stator, rotor side converter control, and back-to-back PWM converters are implemented for the decoupled control. The real-wind speed signal extracted by an anemometer is used for realistic and accurate simulation analysis. Block diagrams for DFIG and control scheme of stator, rotor-side are introduced. Real-time simulation cases are carried out and analyzed for the validity of this work.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.61-69
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• 2010

This paper presents a study of a DFIG wind power generation system for real-time simulations. For real-time simulations, the Real-Time Digital Simulator (RTDS) and its user friendly interface simulation software RSCAD are used. A 2.2MW grid-connected variable speed DFIG wind power generation system is modeled and analyzed in this study. The stator-flux oriented vector control scheme is applied to the stator/rotor side converter control, and the back-to-back PWM converters are implemented for the decoupled control. The real-wind speed signal extracted by an anemometer is used for a realistic, reliable and accurate simulation analysis. Block diagrams, a mathematical presentation of the DFIG and a control scheme of the stator/rotor-side are introduced. Real-time simulation cases are carried out and analyzed for the validity of this work.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.491-498
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• 2008

In this paper a decoupled control of a doubly-fed induction machine(DFIM) feed by a matrix converter is presented. It provides a robust regulation of the stator side active and reactive powers by the direct and quadratic components of the stator current vector, presented in a line-voltage-oriented reference frame. In this case, the stator windings are directly connected to the line grid, while the rotor windings are supplied by this later through a matrix converter controlled by a space vector modulation technique. The proposed solution is suitable for both energy generation and electrical drive applications with restricted speed variation range.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.425-430
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• 2022

A pumped storage power station is an important means to solve the problem of peak load regulation and ensures the safety of power grid operation. The doubly fed variable-speed pumped storage (DFVSPS) system adopts a doubly fed induction machine (DFIM) to replace the synchronous machine used in traditional pumped storage. The stator of DFIM is connected to the power grid, and the three-phase excitation windings are symmetrically distributed on the rotor. Excitation current is supplied by the converter. The active and reactive power of the unit can be quickly adjusted by adjusting the amplitude, frequency, and phase of the rotor-side voltage or current through the converter. Compared with a conventional pumped storage hydropower station (C-PSH), DFVSPS power stations have various operating modes and frequent start-up and shutdown. This study introduces the structure and principle of the DFVSPS unit. Mathematical models of the unit, including a model of DFIM, a model of the pump-turbine, and a model of the converter and its control, are established. Fast power control strategies are proposed for the unit model. A 300 MW model of the DFVSPS unit is established in MATLAB/Simulink, and the response characteristics in generating mode are examined.