DIRECT POWER CONTROL OF A DFIG BASED WIND TURBINS UNDER UNBALANCED GRID VOLTAGE WITHOUT ROTOR POSITION SENSOR
AbstractIn this paper, the behavior of a doubly fed induction generator (DFIG) is proposed under unbalanced grid voltage and without using a rotor position sensor. There are two main methods that are been used for the detection of rotor position: using shaft sensor and sensorless algorithm. In this paper the shaft sensor is eliminated and a position sensorless algorithm is used for estimating the rotor position. Sensorless operation is more desirable than using shaft sensor, because the shaft sensor has several disadvantages related to the cost, cabling, robustness and maintenance. Also, during network unbalance, three selectable control targets are identified for the rotor side converter (RSC), i.e., obtaining sinusoidal and symmetrical stator currents, mitigation of active and reactive powers ripples and the cancellation of electromagnetic torque oscillations. The effectiveness of the proposed control strategy is confirmed by the simulation results from a 2-MW DFIG system. It is concluded that the sensorless algorithm is able to produce accurate results similar to the case of that used from shaft sensor and it can be used in the practical applications.
 Dawei Zhi, and Lie Xu, â€œDirect Power Control of DFIG With Constant Switching Frequency and Improved Transient Performance,â€ IEEE Trans. Energy Conv., Vol. 22, No. 1, Mar., 2007.
 Dawei Zhi, Lie Xu and Barry W. Williams, â€œModel-Based Predictive Direct Power Control of Doubly Fed Induction Generators,â€ IEEE Trans. Power Electron., Vol. 25, No. 2, Feb., 2010.
 Yongchang Zhang, Jiefeng Hu, and Jianguo Zhu, â€œThree-Vectors-Based Predictive Direct Power Control of Doubly Fed Induction Generator for Wind Energy Application,â€ IEEE Trans. Power Electron., Jul., 2014.
 Jiabing Hu, Heng Nian, Bin Hu, Yikang He and Z. Q. Zhu, â€œDirect Active and Reactive Power Regulation of DFIG Using Sliding-Mode Control Approach,â€ IEEE Trans. Energy Conv., Vol. 25, No. 4, Dec., 2010.
 Etienne Tremblay, Sergio Atayde, and Ambrish Chandra, â€œComparative Study of Control Strategies for the Doubly Fed Induction Generator in Wind Energy Conversion Systems: A DSP-Based Implemention Approach,â€ IEEE Trans. Sustain. Energy, Vol. 2, No. 3, Jul., 2011.
 Mohammad Verij Kazemi, Ahmad Sadeghi Yazdankhah, and Hossein Madadi Kojabadi, â€œDirect power control of DFIG based on discrete space vector modulation,â€ Vol 35, Iss. 5, May 2010, Pages 1033â€“1042.
 Rajib Datta and V. T. Ranganathan, â€œA Simple Position Sensorless Algorithm for Rotor Side Field Oriented Control of Wound Rotor Induction machine,â€ IEEE Trans. Ind. Electron., Vol. 48, No. 4, Aug. 2001.
 Gonzalo Abad, Miguel Angel Rodriguez, Grzegorz Iwanski, and Javier Poza, â€œDirect Power Control of Douby-Fed-Induction-Generator-Based Wind Turbine Under Unbalanced Grid Voltage,â€ IEEE Trans. Power Electron., Vol. 25, No. 2, Feb., 2010.
 Lie Xu, and Yi Wang, â€œDynamic Modeling and Control of DFIG-Based Wind Turbines Under Unbalanced Network Condition ,â€ IEEE Trans. Power Syst., Vol. 22, No. 1, Feb., 2007.
 Heng Nian, Yipeng Song, Peng Zhou, and Yikang He, â€œImproved Direct Power Control of a Wind Turbine Driven Doubly Fed Induction Generator During Transient Grid Voltage Unbalance ,â€ IEEE Trans. Energy Conv., Vol. 26, No. 3, Sep. 2011.
 Lie Xu, â€œCoordinated Control of DFIGâ€™s Rotor and Grid Side Converters During Network Unbalance ,â€ IEEE Trans. Power Electron., Vol. 23, No. 3, May 2008.
 Jiefeng Hu, Jianguo Zhu, and David G. Dorrell, â€œPredictive Direct Power Control of Doubly Fed Induction Generators Under Unbalanced Grid Voltage Conditions for Power Quality Improvment ,â€ IEEE Trans. Sustain. Energy, 2014.
 Jiefeng Hu, Jianguo Zhu, and David G. Dorrell, â€œModel-Predictive Direct Power Control of Doubly Fed Induction Generators Under Unbalanced Grid Voltage Conditions in Wind Energy Conditions ,â€ IET Renew. Power Gener., 2014, Vol. 8, Iss. 6, pp. 687â€“695.
 Toshihiko Noguchi, Hiroaki Tomiki, Seiji Kondo, and Isao Takahashi, â€œDirect Power Control of PWM Converter Without Power-Source Voltage Sensors ,â€ IEEE Trans. Ind. Applicat., Vol. 34, No. 3, May/June 1998.