DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications

The power generation system with a doubly fed induction generator (DFIG), which can be used as an autonomous power system after the loss of mains in a distributed generation network, is described. After the mains outage, a fixed frequency and an amplitude of the output voltage are obtained, despite the variable rotor speed. For this reason, it can be successfully applied in the variable-speed wind turbines, adjustable speed water plants, or diesel engines. Moreover, the stand-alone operation of DFIG is useful in a flywheel-based high-energy rotary uninterruptible power supply system. An output voltage is controlled directly by the synchronization of an actual voltage vector with the reference vector represented in a synchronously rotating polar frame. The rotor current angular speed is obtained as a result of vectorial phase-locked loop operation. Any sensors or estimators of the rotor speed or position are unnecessary. Both amplitude and angle control loops are linear. The use of stand-alone operation in grid-connected systems requires mains outage detection. Also, the grid voltage recovery requires a method of synchronization and soft connection of a generator to the grid. The proposed methods of output voltage control, synchronization, and detection of mains loss were tested in a laboratory system.

[1]  T. Thiringer,et al.  Comparison between stator-flux and grid-flux-oriented rotor current control of doubly-fed induction generators , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[2]  Dong-Choon Lee,et al.  Grid Connection of Doubly-Fed Induction Generators in Wind Energy Conversion System , 2006, 2006 CES/IEEE 5th International Power Electronics and Motion Control Conference.

[3]  Sergio Vazquez,et al.  A 800 kW wind-diesel test bench based on the MADE AE-52 variable speed wind turbine , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[4]  W. Koczara,et al.  Sensorless direct voltage control method for stand-alone slip-ring induction generator , 2005, 2005 European Conference on Power Electronics and Applications.

[5]  T. Oka,et al.  Variable speed constant frequency power generating system by the use of rotor excitation of induction machine , 2002, Proceedings of the Power Conversion Conference-Osaka 2002 (Cat. No.02TH8579).

[6]  Wlodzimierz Koczara,et al.  Sensorless Direct Voltage Control of the Stand-Alone Slip-Ring Induction Generator , 2007, IEEE Transactions on Industrial Electronics.

[7]  Z. Krzeminski.  Sensorless multiscalar control of double fed machine for wind power generators , 2002, Proceedings of the Power Conversion Conference-Osaka 2002 (Cat. No.02TH8579).

[8]  Mariusz Malinowski,et al.  A comparative study of control techniques for PWM rectifiers in AC adjustable speed drives , 2003 .

[9]  Wlodzimierz Koczara,et al.  Extended Direct Voltage Control of the Stand-Alone Double Fed Induction Generator , 2007, 2007 International Conference on Power Engineering, Energy and Electrical Drives.

[10]  J. Clare,et al.  MRAS observer for sensorless control of standalone doubly fed induction generators , 2005, IEEE Transactions on Energy Conversion.

[11]  R. W. De Doncker,et al.  Doubly fed induction generator systems for wind turbines , 2002 .

[12]  Toshihiko Noguchi,et al.  Direct power control of PWM converter without power source voltage sensors , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[13]  Maria Ines Valla,et al.  Vector control strategy for a doubly-fed stand-alone induction generator , 2002, IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02.

[14]  S. K. Salman,et al.  New loss of mains detection algorithm for embedded generation using rate of change of voltage and changes in power factors , 2001 .

[15]  Frede Blaabjerg,et al.  Overview of Control and Grid Synchronization for Distributed Power Generation Systems , 2006, IEEE Transactions on Industrial Electronics.

[16]  J.C. Clare,et al.  Vector controlled induction machines for stand-alone wind energy applications , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[17]  J. Uceda,et al.  Uninterruptible power supply systems provide protection , 2007, IEEE Industrial Electronics Magazine.

[18]  Mauricio Aredes,et al.  Analysis and Software Implementation of a Robust Synchronizing PLL Circuit Based on the pq Theory , 2006, IEEE Transactions on Industrial Electronics.

[19]  R. Datta,et al.  Direct power control of grid-connected wound rotor induction machine without rotor position sensors , 2001 .

[20]  F. Blaabjerg,et al.  Flexible control of small wind turbines with grid failure detection operating in stand-alone and grid-connected mode , 2004, IEEE Transactions on Power Electronics.

[21]  W. Koczara,et al.  Grid Connection to Stand Alone Transitions of Slip Ring Induction Generator During Grid Faults , 2006, 2006 CES/IEEE 5th International Power Electronics and Motion Control Conference.

[22]  W. Koczara,et al.  Sensorless stand alone variable speed system for distributed generation , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).