Control of Variable Pitch and Variable Speed Direct-drive Wind Turbines in Weak Grid Systems with Active Power Balance

In the case of operating in a weak grid system, when wind power becomes a significant portion of the power system or even the sole energy source, the wind power generators and converters are expected to help maintain the grid voltage. The grid-side converter needs to work as a voltage source to help regulate the terminal (grid) voltage amplitude and frequency by adjusting the reactive power and active power flow, respectively. For a direct-drive permanent magnet synchronous generator with a full power converter, the active power must be provided by the captured wind power. The active power flow between the source (captured wind power) and the grid (load) must be balanced by actively controlling the generator speed and wind turbine pitch angle. In the study, the coordinated control of generator speed and blade pitch angle is proposed together with a dc-link voltage controller. A model of the grid-side converter operating as a voltage source has been built and the strategy regarding voltage and frequency regulation is presented. Simulation is carried out with different wind and load profile. The results show the wind energy can help support the weak grid and power the local grid in stand-alone mode as well.

[1]  Kashem M. Muttaqi,et al.  A control approach for voltage and frequency regulation of a Wind-Diesel-battery based hybrid remote area power supply system , 2010, IECON 2010 - 36th Annual Conference on IEEE Industrial Electronics Society.

[2]  H. Siguerdidjane,et al.  Nonlinear control of variable speed wind turbines for power regulation , 2005, Proceedings of 2005 IEEE Conference on Control Applications, 2005. CCA 2005..

[3]  Toshiaki Murata,et al.  Output Power Smoothing and Hydrogen Production by Using Variable Speed Wind Generators , 2010, IEEE Transactions on Industrial Electronics.

[4]  J.A. Ferreira,et al.  Wind turbines emulating inertia and supporting primary frequency control , 2006, IEEE Transactions on Power Systems.

[5]  M. Chinchilla,et al.  Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid , 2006, IEEE Transactions on Energy Conversion.

[6]  E. Muljadi,et al.  Effect of Variable Speed Wind Turbine Generator on Stability of a Weak Grid , 2007, IEEE Transactions on Energy Conversion.

[7]  F. Wang,et al.  Dc-link voltage control of full power converter for wind generator operating in weak grid systems , 2009, 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition.

[8]  K.. De Brabandere,et al.  A Voltage and Frequency Droop Control Method for Parallel Inverters , 2007, IEEE Transactions on Power Electronics.

[9]  Nikos D. Hatziargyriou,et al.  The effect of variable-speed wind turbines on the operation of weak distribution networks , 2002 .

[10]  L. Ran,et al.  Use of turbine inertia for power smoothing of wind turbines with a DFIG , 2004, 2004 11th International Conference on Harmonics and Quality of Power (IEEE Cat. No.04EX951).

[11]  Anca Daniela Hansen,et al.  Multi-pole permanent magnet synchronous generator wind turbines' grid support capability in uninterrupted operation during grid faults , 2009 .

[12]  Ming Cheng,et al.  Pitch angle control for variable speed wind turbines , 2008, 2008 Third International Conference on Electric Utility Deregulation and Restructuring and Power Technologies.

[13]  A. Keyhani,et al.  Control of distributed generation systems-Part I: Voltages and currents control , 2004, IEEE Transactions on Power Electronics.

[14]  Tomonobu Senjyu,et al.  Output power leveling of wind turbine Generator for all operating regions by pitch angle control , 2006 .

[15]  J. F. Conroy,et al.  Low-voltage ride-through of a full converter wind turbine with permanent magnet generator , 2007 .

[16]  N.D. Hatziargyriou,et al.  Control of Variable Speed Wind Turbines in Islanded Mode of Operation , 2008, IEEE Transactions on Energy Conversion.

[17]  R. Cardenas,et al.  Sensorless vector control of induction machines for variable-speed wind energy applications , 2004, IEEE Transactions on Energy Conversion.

[18]  M. Negnevitsky,et al.  Control of a stand alone variable speed wind turbine with a permanent magnet synchronous generator , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[19]  Marco Liserre,et al.  Overview of Multi-MW Wind Turbines and Wind Parks , 2011, IEEE Transactions on Industrial Electronics.

[20]  T.C. Green,et al.  Modeling, Analysis and Testing of Autonomous Operation of an Inverter-Based Microgrid , 2007, IEEE Transactions on Power Electronics.

[21]  T.C. Green,et al.  Energy Management in Autonomous Microgrid Using Stability-Constrained Droop Control of Inverters , 2008, IEEE Transactions on Power Electronics.

[22]  Qing-Chang Zhong,et al.  Static synchronous generators for distributed generation and renewable energy , 2009, 2009 IEEE/PES Power Systems Conference and Exposition.

[23]  Boon-Teck Ooi,et al.  Strategies to Smooth Wind Power Fluctuations of Wind Turbine Generator , 2007, IEEE Transactions on Energy Conversion.

[24]  Liangzhong Yao,et al.  Novel Integration of DFIG-Based Wind Generators Within Microgrids , 2011, IEEE Transactions on Energy Conversion.

[25]  T. Yamazaki,et al.  Smoothing control of wind generator output fluctuations by new pitch controller , 2008, 2008 18th International Conference on Electrical Machines.