• Journal of Electrical Engineering and Technology
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• 제5권3호
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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.

• 전기학회논문지
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• 제57권6호
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• pp.985-993
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• 2008

This paper proposes a new DFIG(Doubly-Fed Induction Generator) system using matrix converter, which is very effectively used for interconnecting the wind power system to the power grid. The operation of proposed system was verified by computer simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was conformed by experimental works with a laboratory scaled-model of wind power system. The laboratory scaled-model was built using a motor-generator set with vector drive system, and a matrix converter with DSP(Digital Signal Processor). The operation of scaled-model was tested by modeling the specific variable-speed wind turbine using the real wind data in order to make the scaled-model simulate the real wind power system as close as possible. The simulation and experimental results confirm that matrix converter can be applied for the DFIG system.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1571-1581
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• 2016

A novel method is proposed to construct the voltage stability boundary of power system considering different Reactive Power Control Mode (RPCM) of Doubly-Fed Induction Generator (DFIG) Wind Power Plant (WPP). It can be used for reflecting the static stability status of grid operation with wind power penetration. The analytical derivation work of boundary search method can expound the mechanism and parameters relationship of different WPP RPCMs. In order to improve the load margin and find a practical method to assess the voltage security of power system, the approximate method of constructing voltage stability boundary and the critical points search algorithms under different RPCMs of DFIG WPP are explored, which can provide direct and effective reference data for operators.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.257-260
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• 2006

This paper presents a design approach for wind power generator. Among several different generator systems, doubly-fed induction generator(DFIG) is selected for Hyosung 2MW wind turbine system from the view of cost and weight. The time step finite element method is applied to analyze the performance of DFIG, and design of experiment(DOE) is used as an optimization method.

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.614-622
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• 2010

This paper presents a control method, which reduces the pulsating torque and DC voltage problems of a doubly fed induction generator (DFIG)-based wind turbine system. To reduce the torque and power ripple, a current control scheme consisting of a proportional integral (PI) controller is presented in a positive synchronously rotating reference frame, which is capable of providing precise current control for a rotor-side converter with separated positive and negative components. The power theory can reduce the oscillation of the DC-link voltage in the grid-side converter. In this paper, the generator model is examined, and simulation results are obtained with a 3 kW DFIG-based wind turbine system to verify the proposed control strategy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.322-325
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• 1997

Concerns for wind energy as alternative energy have been highly increased. In this paper, the mechanism between mechanical wind turbine and power generating system is presented to specify the relationship of the energy transfer. Grid-connected DFIG could achieve unity leading power factor, in addition to variable speed operation at the wide sub-synchronous and super-synchronous shaft speed range and also its independent control of torque and reactive power is possible.

• Journal of Power Electronics
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• 제10권6호
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• pp.724-732
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• 2010

This paper presents an effective rotor current controller for variable-speed stand-alone doubly fed induction generator (DFIG) systems feeding an unbalanced three-phase load. The proposed current controller is developed based on proportional plus two resonant regulators, which are tuned at the positive and negative slip frequencies and implemented in the rotor reference frame without decomposing the positive and negative sequence components of the measured rotor current. In addition, the behavior of the proposed controller is examined in terms of control performance and stability with respect to rotor speed variations, i.e., slip frequency variations. Simulations and experimental results are shown to validate the robustness and effectiveness of the proposed control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.460_461
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• 2009

This paper analyzes the steady state characteristics for variable speed wind power system with doubly-fed induction generator(DFIG). This paper explains the equivalent circuit and phasor diagram of DFIG for different operating conditions. It also simulates the torque-slip characteristics with respect to changes of different parameters. Simulation results show the torque-slip characteristics, stator power factor-rotor voltage and stator current-rotor voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.326-329
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• 1997

This paper deals with the generating power analysis of wound rotor induction generator according to the rotor excitation for use of DFIG (Doubly Fed Induction Generator) system in wind power generation as a part of renewable energy development. In this way, the generating power of wound rotor induction generator can be achieved for a wide range wind speed of supersynchronous and subsynchronous speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1234-1235
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• 2007

This paper represents the generating principles of the doubly-fed induction generator (DFIG) based wind power system and developes a simulation model of DFIG by using PSCAD/EMTDC. In addition, this paper analyzes the steady state operation and the transient operation during the voltage sags in the power common coupling. The voltage sags are occurred by three phase line-to-ground faults and full-voltage startup of an induction motor in the simulation.