Rotor Voltage Dynamics in the Doubly Fed Induction Generator During Grid Faults

This paper presents a new control strategy for the rotor-side converter (RSC) of wind turbines (WTs) based on doubly fed induction generators (DFIG) that intends to improve its low-voltage ride through capability. The main objective of this work is to design an algorithm that would enable the system to control the initial overcurrents that appear in the generator during voltage sags, which can damage the RSC, without tripping it. As a difference with classical solutions, based on the installation of crowbar circuits, this operation mode permits to keep the inverter connected to the generator, something that would permit the injection of power to the grid during the fault, as the new grid codes demand. A theoretical study of the dynamical behavior of the rotor voltage is also developed, in order to show that the voltage at the rotor terminals required for the control strategy implementation remains under controllable limits. In order to validate the proposed control system simulation, results have been collected using PSCAD/EMTDC and experimental tests have been carried out in a scaled prototype.

[1]  J.V. Milanovic,et al.  Assessing Transient Response of DFIG-Based Wind Plants—The Influence of Model Simplifications and Parameters , 2008, IEEE Transactions on Power Systems.

[2]  R.G. Harley,et al.  Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG , 2008, IEEE Transactions on Power Electronics.

[3]  Waldo Vinton Lyon,et al.  Applications of the method of symmetrical components , 1937 .

[4]  J. Morren,et al.  Ridethrough of wind turbines with doubly-fed induction generator during a voltage dip , 2005, IEEE Transactions on Energy Conversion.

[5]  F. Blaabjerg,et al.  Advanced Grid Synchronization System for Power Converters under Unbalanced and Distorted Operating Conditions , 2006, IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics.

[6]  Paul-Etienne Vidal,et al.  Dual Direct Torque Control of Doubly Fed Induction Machine , 2007, IEEE Transactions on Industrial Electronics.

[7]  F. Mei,et al.  Modal Analysis of Grid-Connected Doubly Fed Induction Generators , 2006, IEEE Transactions on Energy Conversion.

[8]  Le-Ren Chang-Chien,et al.  Dynamic reserve allocation for system contingency by DFIG wind farms , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[9]  J. López,et al.  Wind Turbines Based on Doubly Fed Induction Generator Under Asymmetrical Voltage Dips , 2008, IEEE Transactions on Energy Conversion.

[10]  Poul Ejnar Sørensen,et al.  Mapping of grid faults and grid codes , 2007 .

[11]  Dewei Xu,et al.  Modeling and Control of Brushless Doubly-Fed Induction Generators in Wind Energy Applications , 2008, APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition.

[12]  I. Erlich,et al.  Advanced grid requirements for the integration of wind turbines into the German transmission system , 2006, 2006 IEEE Power Engineering Society General Meeting.

[13]  G. Abad,et al.  Two-Level VSC Based Predictive Direct Torque Control of the Doubly Fed Induction Machine With Reduced Torque and Flux Ripples at Low Constant Switching Frequency , 2008, IEEE Transactions on Power Electronics.

[14]  G. Joos,et al.  Effect of low voltage ride through (LVRT) characteristic on voltage stability , 2005, IEEE Power Engineering Society General Meeting, 2005.

[15]  Greg Asher,et al.  MRAS Observers for Sensorless Control of Doubly-Fed Induction Generators , 2008 .

[16]  Scott D. Sudhoff,et al.  Analysis of Electric Machinery and Drive Systems , 1995 .

[17]  I. Erlich,et al.  Modeling of Wind Turbines Based on Doubly-Fed Induction Generators for Power System Stability Studies , 2007, IEEE Transactions on Power Systems.

[18]  C. Fortescue.  Method of Symmetrical Co-Ordinates Applied to the Solution of Polyphase Networks , 1918, Transactions of the American Institute of Electrical Engineers.

[19]  Peter Tavner,et al.  Control of a doubly fed induction generator in a wind turbine during grid fault ride-through , 2006 .

[20]  Wlodzimierz Koczara,et al.  DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications , 2008, IEEE Transactions on Industrial Electronics.

[21]  A. Morales,et al.  Advanced grid requirements for the integration of wind farms into the Spanish transmission system , 2008 .

[22]  Frede Blaabjerg,et al.  Power Electronics for Modern Wind Turbines , 2006, Power Electronics for Modern Wind Turbines.

[23]  M. Kayikci,et al.  Reactive Power Control Strategies for DFIG-Based Plants , 2007, IEEE Transactions on Energy Conversion.

[24]  S. Arnalte,et al.  Dynamic Programming Power Control for Doubly Fed Induction Generators , 2008, IEEE Transactions on Power Electronics.

[25]  N. Mohan,et al.  Control of a Doubly Fed Induction Wind Generator Under Unbalanced Grid Voltage Conditions , 2007, IEEE Transactions on Energy Conversion.

[26]  J. Morren,et al.  Short-Circuit Current of Wind Turbines With Doubly Fed Induction Generator , 2007, IEEE Transactions on Energy Conversion.

[27]  H. Stemmler,et al.  Stationary frame generalized integrators for current control of active power filters with zero steady state error for current harmonics of concern under unbalanced and distorted operation conditions , 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).

[28]  S. Arnalte,et al.  Direct Power Control Applied to Doubly Fed Induction Generator Under Unbalanced Grid Voltage Conditions , 2008, IEEE Transactions on Power Electronics.

[29]  Lie Xu,et al.  Direct active and reactive power control of DFIG for wind energy generation , 2006, IEEE Transactions on Energy Conversion.

[30]  Hui Li,et al.  An Improved Control Strategy of Limiting the DC-Link Voltage Fluctuation for a Doubly Fed Induction Wind Generator , 2008, IEEE Transactions on Power Electronics.

[31]  Z.A. Styczynski,et al.  Dynamic simulation of renewable energy sources and requirements on fault ride through behavior , 2006, 2006 IEEE Power Engineering Society General Meeting.

[32]  Werner Leonhard,et al.  Control of Electrical Drives , 1990 .

[33]  Remus Teodorescu,et al.  A New Single-Phase PLL Structure Based on Second Order Generalized Integrator , 2006 .

[34]  J. Niiranen,et al.  Ride-Through Analysis of Doubly Fed Induction Wind-Power Generator Under Unsymmetrical Network Disturbance , 2006, IEEE Transactions on Power Systems.

[35]  G. Venkataramanan,et al.  A Fault Tolerant Doubly Fed Induction Generator Wind Turbine Using a Parallel Grid Side Rectifier and Series Grid Side Converter , 2008, IEEE Transactions on Power Electronics.

[36]  P. Sanchis,et al.  Dynamic Behavior of the Doubly Fed Induction Generator During Three-Phase Voltage Dips , 2007, IEEE Transactions on Energy Conversion.

[37]  Lie Xu,et al.  Coordinated Control of DFIG's Rotor and Grid Side Converters During Network Unbalance , 2008, IEEE Transactions on Power Electronics.