• Title, Summary, Keyword: Doubly-fed induction generator (DFIG)

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D-q Equivalent Circuit-based Protection Algorithm for a Doubly-fed Induction Generator in the Time Domain

  • Kang, Yong-Cheol;Kang, Hae-Gweon;Lee, Ji-Hoon
    • 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.

Characteristics on Stand-alone Operation of a Doubly-fed Induction Generator Applied to Adjustable Speed Gas Engine Cogeneration System

  • Daido, Tetsuji;Miura, Yushi;Ise, Toshifumi;Sato, Yuki
    • Journal of Power Electronics
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    • v.13 no.5
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    • pp.841-853
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    • 2013
  • An application of doubly-fed induction generator (DFIG), which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine cogeneration system. However, the DFIG requires initial excitation for startup during a blackout because the DFIG has no excitation source. In this paper, we propose the "blackout start" as a new excitation method to generate a rated voltage at the primary side during a blackout. In addition, a stand-alone operation following a blackout has been investigated by using experimental setup with a real gas engine. Power flows in the generating set with the DFIG at the stand-alone operation have been investigated experimentally. Experimental investigation of the power flow suggests that the generating set with DFIG has optimal speed in minimizing whole system losses.

A Voltage Vector Synchronization Method for a Renewable Energy System with a Doubly-Fed Induction Generator (권선형유도발전기를 갖는 신재생에너지 시스템을 위한 전압벡터 동기화 기법)

  • Park, Jung-Woo;Lee, Ki-Wook;Kim, Dong-Wook
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.3
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    • pp.547-555
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    • 2007
  • In order to transmit energy generated through the stator winding of a doubly-fed induction generator (DFIG), we need to synchronize the generated voltage vector with the grid voltage vector. However, the existing synchronization methods work only when the encoder is installed at a specific position and equivalent constant is precise. In order to solve this problem, a new synchronization method has been proposed and a way of applying the method to existing doubly-fed induction generator control algorithm has been also proposed. The validities of the methods proposed were verified by using a prototype converter for a 1.5MW-class doubly-fed induction generator and experimental results showed the validity of that against variation of an encoder positions, generator parameters, and grid voltages.

Power Analysis of Grid Connected Doubly Fed Induction Generator for Wind Power Generating System (풍력발전용 계통연계 DFIG의 출력 해석)

  • Lee, Hyun-Chae;Seo, Young-Taek;Oh, Chul-Soo
    • Proceedings of the KIEE Conference
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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.

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Small Signal Stability Analysis of Doubly Fed Induction Generator including SDBR

  • Shawon, Mohammad Hasanuzzaman;Al-Durra, Ahmed;Caruana, Cedric;Muyeen, S.M.
    • Journal of international Conference on Electrical Machines and Systems
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    • v.2 no.1
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    • pp.31-39
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    • 2013
  • This paper presents small signal stability analysis of a doubly fed induction generator (DFIG) based wind farm including series dynamic braking resistor (SDBR) connected at the stator side. A detailed mathematical model of wind turbine, DFIG machine and converters and SDBR is presented in this paper to derive the complete dynamic equations of the studied system. Small signal stability of this system is carried out by modal and sensitivity analysis, participation factors and eigenvalue analysis. Finally, this paper presents an analysis of the dynamic behavior of DFIG based wind farm under voltage dip condition with and without SDBR.

Comparative study of control strategies for the induction generators in wind energy conversion system

  • Giribabu, D.;Das, Maloy;Kumar, Amit
    • Wind and Structures
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    • v.22 no.6
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    • pp.635-662
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    • 2016
  • This paper deals with the comparison of different control strategies for the Induction generators in wind energy conversion system. Mainly, two types of induction machines, Self excited induction generator (SEIG) and doubly Fed Induction generators (DFIG) are studied. The different control strategies for SEIG and DFIG are compared. For SEIG, Electronic load Controller mechanism, Static Compensator based voltage regulator are studied. For DFIG the main control strategy namely vector control, direct torque control and direct power control are implemented. Apart from these control strategies for both SEIG and DFIG to improve the performance, the ANFIS based controller is introduced in both STATCOM and DTC methods. These control methods are simulated using MATLAB/SIMULINK and performances are analyzed and compared.

An Improved Control Strategy Using a PI-Resonant Controller for an Unbalanced Stand-Alone Doubly-Fed Induction Generator

  • Phan, Van-Tung;Lee, Hong-Hee;Chun, Tae-Won
    • Journal of Power Electronics
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    • v.10 no.2
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    • pp.194-202
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    • 2010
  • The main cause of degradation in an unbalanced stand-alone doubly-fed induction generator (DFIG) system is negative sequence components that exist in the generated stator voltages. To eliminate these components, a hybrid current controller composed of a proportional-integral controller and a resonant regulator is developed in this paper. The proposed controller is applied to the rotor-side converter of a DFIG system for the purpose of compensating the negative stator voltage sequences. The proposed current controller is implemented in a single positive rotating reference frame and therefore the controller can directly regulate both the positive and negative sequence components without the need for sequential decomposition of the measured rotor currents. In terms of compensation capability and accuracy, simulations and experimental results demonstrated the excellent performance of the proposed control method when compared to conventional vector control schemes.

Grid Connection Algorithm for Doubly-Fed Induction Generator Using Rotor Side PWM Inverter-Converter (회전자측 PWM 인버터-컨버터를 사용한 이중여자 유도형 풍력 발전기의 계통 투입 알고리즘)

  • 정병창;권태화;송승호;김일환
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.10
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    • pp.528-534
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    • 2003
  • A grid connection algorithm is proposed for the doubly-fed induction generator (DFIG) which is widely adopted in high power variable speed wind turbine. Before the stator of DFIG is connected to grid, rotor-side converter is used to control the induced stator voltage. As a result, the stator transient current is limited below the rate value during the connection by the proposed synchronization of the stator voltage to the grid voltage. A wind power generation simulator using DC motor and wound-rotor induction generator is built and the dynamic characteristics of proposed algorithm is verified experimentally.

New Control Scheme for the Wind-Driven Doubly Fed Induction Generator under Normal and Abnormal Grid Voltage Conditions

  • Ebrahim, Osama S.;Jain, Praveen K.;Nishith, Goel
    • Journal of Power Electronics
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    • v.8 no.1
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    • pp.10-22
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    • 2008
  • The wind-driven doubly fed induction generator (DFIG) is currently under pressure to be more grid-compatible. The main concern is the fault ride-through (FRT) requirement to keep the generator connected to the grid during faults. In response to this, the paper introduces a novel model and new control scheme for the DFIG. The model provides a means of direct stator power control and considers the stator transients. On the basis of the derived model, a robust linear quadratic (LQ) controller is synthesized. The control law has proportional and integral actions and takes account of one sample delay in the input owing to the microprocessor's execution time. Further, the influence of the grid voltage imperfection is mitigated using frequency shaped cost functional method. Compensation of the rotor current pulsations is proposed to improve the FRT capability as well as the generator performance under grid voltage unbalance. As a consequence, the control system can achieve i) fast direct power control without instability risk, ii) alleviation of the problems associated with the DFIG operation under unbalanced grid voltage, and iii) high probability of successful grid FRT. The effectiveness of the proposed solution is confirmed through simulation studies on 2MW DFIG.

Analysis of Dynamic Characteristics for Doubly-Fed Induction Generator in Wind Turbine System based on Stiffness of Linked System (연계계통의 강인성에 따른 이중여자유도발전 풍력시스템의 동특성 해석)

  • Kim, Tae-Ho;Ro, Kyoung-Soo
    • Proceedings of the KIEE Conference
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    • pp.458_459
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    • 2009
  • This paper analyzes the dynamic characteristics for doubly-fed induction generator(DFIG) in wind turbine system. This paper presents a modeling and simulation of a grid-connected wind turbine generation system for dynamics analysis on MATLAB/Simulink, and analyzes the responses DFIG wind turbine system for stiffness of linked system. Simulation results show the variations of generator's active/reactive output, terminal voltage, fault current, etc.

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