Conference programme

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Wednesday, 18 November 2015
11:30 - 13:00 Wind power supporting the grid
Integrating wind power into the electricity market  
Onshore      Offshore    


Room: Belleville

The aim of the session is to present advances on techniques that permit to wind farms to support the grid both in terms of frequency and voltage.  The ability to provide such services is one of the challenges today for increasing wind penetration. The session addresses also the potential of increasing wind penetration when considering smart grid problematics.

Learning objectives

  • Advances in techniques enabling wind turbines to comply with emerging grid codes for system services
  • Insight to the possibility offered by wind farms to contribute to frequency control
  • Advances in voltage management in grids with high wind penetration
  • How the control capabilities of wind farms can be used to mitigate any negative impacts on grid stability
  • How to increase wind penetration considering complementarity with demand with focus on electric vehicles
Lead Session Chair:
Alfredo Parres, ABB Group, Spain
George Kariniotakis, Professor, Centre for Processes, Renewable Energies and Energy Systems (PERSEE), MINES Paris Tech, France
Ervin Bossanyi DNV GL, United Kingdom
Co-authors:
Ervin Bossanyi (1) F
(1) DNV GL, Bristol, United Kingdom

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Following a physics degree and a PhD in energy economics, Ervin Bossanyi gained 37 years’ experience in many aspects of wind energy and other renewables in the academic, industrial and consultancy sectors, working for Reading University, the Science Research Council, Wind Energy Group Ltd, and finally Garrad Hassan (now DNV GL). Main contributions include development of advanced control concepts for commercial wind turbines, novel transmission systems, detailed simulation modelling including development of the Bladed code, grid integration of renewables, turbulence modelling, forecasting, and operation and maintenance planning. He is now senior principal researcher for strategic research and innovation in renewables.

Abstract

Generic grid frequency response capability for wind power plant

Introduction

With high renewables penetration, the increasing proportion of non-synchronous generation feeding into the grid through inverters causes system operators to worry about reduced system inertia and its effect on grid frequency stability. However, most modern wind turbines could help significantly by providing fast frequency response through controller modifications, and a few manufacturers already offer this. This paper presents a generic approach, which may even be suitable for retrofit, and considers possible implications for the turbine. Control at the wind farm level provides further flexibility in tailoring the response.

Approach

To provide fast frequency response a turbine should ideally be able to reduce as well as transiently increase its power production, both above and below rated. The scope for this varies according to the wind conditions and the operating state of the turbine, and a full understanding of these is required to achieve maximum potential. A generic approach for this is developed, and detailed dynamic simulations are used to demonstrate and test its performance.

Main body of abstract

By measuring grid frequency and commanding changes in power output, wind turbines can provide synthetic or emulated inertia by making use of the rotor as a kinetic energy store below rated, and by modifying pitch control above rated. This is not quite the same as true synchronous inertia; on the other hand it is programmable, giving the flexibility to include primary response over seconds or tens of seconds which can be tailored for maximum benefit to the grid at any time, just as long as the turbine remains within acceptable operational limits. These are defined by aerodynamic performance and the need to avoid stall, the operational rotor speed range, instantaneous power and current limits of electrical components, thermal limits, and structural loading. Using a simple estimator for the wind speed and turbine state, the calculation of these limits is described, and a method to implement the resulting change in power is presented. The implications for turbine design are discussed, and the potential for a retrofit package interposed between the turbine and its normal controller is considered. The proposed solution allows maximum fast frequency response potential at the turbine level, either on its own or in combination with delta control to provide a spinning reserve margin. Detailed simulations allow full assessment of any turbine loading implications, including any effect on extreme loads e.g. during grid faults. Finally the scope for control modifications at the wind farm level is considered; this could further increase the flexibility of the whole wind power plant to tailor its response to grid system needs.

Conclusion

To help maintain stable grid operation with a high penetration of wind power, modern wind turbines can be made to change their power output to comply with system operator requirements for spinning reserve and/or to respond to measured grid frequency variations. A generic approach is presented whereby the wind turbine control action can be modified to meet any desired change of power output (an increase as well as a decrease) with very rapid response, restricted only when necessary to ensure that the turbine remains within acceptable operational limits. This should allow wind turbines to maximise their ability to comply with emerging grid codes for fast frequency response, and help ensure that high penetrations of wind energy can be achieved in the future.


Learning objectives
Manufacturers: to understand how their turbines can maximise grid frequency support potential;
Wind plant operators: to appreciate the scope for provision of frequency response as an ancillary service to the grid, including retrofit possibilities;
Grid planners and operators: to understand how far wind turbines can help enhance grid frequency stability and short-term power balancing.