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Wednesday, 12 March 2014
16:30 - 18:00 Storage & grid integration
Hardware Technology  


Room: Tramuntana
Session description

As wind energy becomes an increasingly important power supply technology in many countries, the wind energy sector has to keep on working in collaboration with system operators and develop the technological solutions that are required. This session will present new developments that will consolidate wind energy as a major element of electricity systems: wind turbine group (WTG) hardware and software, new control strategies from WTG to global power systems as well as storage solutions.

Learning objectives

  • Identify new WTG capabilities for grid operation support
  • Analyse new control strategies at both WTG and wind farm level
  • Understand how wind energy will/can be managed in future scenarios and at high penetrations
  • Examine what is at stake to consolidate wind energy as the future leading energy source
  • Identify and analyse electricity storage business models
Lead Session Chair:
Luis Polo, AEE, Spain

Co-chair(s):
Santiago Arnaltes, University Carlos III of Madrid - UC3M, Spain
Alejandro Gonzalez Murua Acciona Winpower, Spain
Co-authors:
TO BE DEFINED TO BE DEFINED (1) F P Teresa Arlabán (1) Oscar Alonso (1) Daniel Ortiz (1) Ana Fernández (1) Alberto García-Barace (1) Alejandro González (1) Guillermo Beriain (1) Antonio Torres (1) Jose Luis Aristegui (1)
(1) Acciona Winpower, Imarcoain, Spain

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Alejandro Gonzalez Murua received the M.Sc. degree in Telecommunications Engineering from the Public University of Navarre, Pamplona, Spain, in 2001 and obtained a MBA degree from ESIC Business&Marketing School in 2011.
He has been working in the renewables industry as a control engineer for more than 10 years and has been involved in several projects, some of them related to the wind generation control strategies for grid integration.
He is currently the Control Engineering Area Manager in the R&D&I Department at Acciona Windpower.

Abstract

Innovative strategy for a fast and precise frequency control provided by wind turbines

Introduction

Historically, distributed generation units (DGUs), as for example, those based on wind or solar energy, have no not been required by grid operators to collaborate in grid frequency stability. However, in view of the spectacular increase in installed power of this type of generating units in recent years, active power control requirements according to frequency deviations are being imposed by most grid operators throughout the world.

Approach

At present, two control structures are used to adapt active power generated by wind-based generating units to grid frequency:
• Local control at wind turbine (WT) level: a fast though uncoordinated response can be achieved.
• Central control at substation level (SC): a coordinated response can be achieved, although slower than that of previous structure due to communication delays.
A novel process for controlling the active power generated by a WF that combines the fast response characteristic of local control systems and the coordination of central control systems is presented.


Main body of abstract

Proposed novel strategy for controlling the active power generated by a WF is based on the next process:
• The substation controller decides which WTs will provide frequency control in case of a deviation occurring in the grid; those WTs being in charge of responding for the whole WF.
• Those parameters are sent to chosen WTs, which adjust their frequency controllers according to them;
• Then, if a frequency deviation occurs, just selected WTs will react immediately on a local level based on received parameters (the rest remaining unaltered) and therefore, responding in a coordinated manner but avoiding typical state-of-the-art delays.
• The substation controller keeps acting as a supervisor and, if any errors from expected wind farm response are detected when a frequency deviation happens, other wind turbines will be set to react.
This control concept has been fully implemented and tested:
• The WT control loops at local level have been adjusted to provide accurate response both at part-rate and full rate-power ranges, when either the torque control or pitch control or both, are in charge of ensuring proper active power control speed and accuracy.
• In order to check the limits and rate of change of active power provided by a single WT, control simulations and load calculations have been performed that are shown in the paper.
• Also, tests on a real wind turbine and wind farm have been done to check the stationary performance at reduced load and dynamic changes


Conclusion

A new control concept has been presented with some advantages with respect prior art:
• accuracy (a WT can adjust its power more accurately for a 15% power reduction, providing a 1.5% required reduction for 10 WT as stated by the grid operator);
• speed: local control loops are faster than centralized ones;
• coordination between WTs once an error in frequency happens.



Learning objectives
• Learn about commonly used strategies for frequency control by wind turbines: its pros and cons.
• Discover a new control strategy superior to conventional controllers in terms of accuracy and speed.
• Graphically confirm the robustness of the new controller by simulation and field test results.