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SAFER, SMARTER, GREENER
Infrastructures to enable wind and solar projects to actively participate in balancing European grids
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Keir Harman, Director, Asset Operations and Management
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Overview
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The opportunities available to a wind farm owner
Balancing the grid in the UK
Controlling wind farm output
Forecasting and communications
The opportunities available to the wind farm owner
With the rapid increase of renewable energy penetrating our grid systems there is a strong
demand for all wind projects to operate more like conventional generating plants:
Visible
Predictable
Controllable
Opportunity: wind farm owners can offer balancing and other ancillary services to the grid
system operator and receive additional revenue
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Balancing the grid in the UK
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VisiblePredictableControllable
More Less
~7GW transmission
connected wind
~5GW
embedded
wind
~5GW
embedded
solar
Storage
‘coming very soon’
Balancing the grid in the UK
National Grid has a licence obligation to control frequency within the limits, i.e. +/- 1% of
nominal system frequency (50.00Hz)
– If demand is greater than generation, then frequency falls
– If generation is greater than demand, then frequency rises
National Grid must also control voltage within legal limits
National Grid procures services in order to balance demand and supply and to ensure the
security and quality of electricity supply across the GB Transmission System
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System Operator’s role:
(1) Manage electricity flow across the networks and (2) balance generation and demand
Balancing the grid in the UK
Main procured services:
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Frequency response
Reserve (energy and system balancing)
Constraint management
Reactive power (voltage control)
Intertrips
Balancing the grid in the UK
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Time lapse of 12 hours of operation on 11 April 2016
http://www.gridwatch.templar.co.uk/
Controlling wind farm output
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There’s plenty of
inertia available!
?
Controlling wind farm output
Power decrease Power increase
Possible? Yes, always possible as long as some power is being generated
Yes, only transient (unless the turbine is already operating at deliberately reduced power level)
How?(above rated wind speed)
Set-point reduction (speed,torque or both), results in increased pitch angle
Decrease the pitch angle to capture power that was being discarded. Can only be deployed for a limited time to avoid over-heating or excess loading
How?(Below rated wind speed)
Increased fine pitch angle Rotor must slow down so that kinetic energy can be used. Can only be sustained for a limited time before rotational speed is allowed to recover
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Controlling wind farm output: Power decrease (delta control)
Below rated wind speed Above rated wind speed
Controlling wind farm output: Power increase
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Below rated wind speed Above rated wind speed
Controlling wind power output: shaping
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Combine both decrease and increase
power control strategies to shape a
required production profile
Complex control results in a dynamic
power curve
1Hz or higher data will be required to
analyse performance
Controlling wind power output: Whole farm shaping
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Turbine responses can be delayed
and shaped individually providing
further flexibility in shaping the
response of the whole wind farm
The control systems for the
turbines and wind farms can be
retrofitted
A hybrid system may include a
storage device to extend overall
capability
Time [s]
Unit p
ow
er
Source: Generic grid frequency response capability for wind power plant E. A. Bossanyi, EWEA Annual
conference November 2015
Forecasting (production and availability)
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Accurate forecasting is essential when providing balancing or ancillary services
Communications for balancing and ancillary services (UK)
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National Grid control roomRenewables control room
Transmission connected
• Real-time metering
• Forecasts provided (physical notification)
• Control instruction system provided (dispatch)
Distribution connected (embedded)
• Real time metering possible
• Accurate forecasts possible
• Control via ‘aggregation’ supported and possible
Conclusion
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There is plenty of scope for wind farms to provide frequency response and other ancillary and
balancing services
The market is developing fast and not just for large scale wind projects
To integrate successfully on our grid systems, wind projects need to be:
VisiblePredictableControllable
