Infrastructures to enable wind and solar projects to
actively participate in balancing European grids
Keir Harman, Director, Asset Operations and Management
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SAFER, SMARTER, GREENER
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Overview
 The opportunities available to a wind farm owner
 Balancing the grid in the UK
 Controlling wind farm output
 Forecasting and communications
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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
~7GW transmission
connected wind
More
~5GW
embedded
wind
Visible
Predictable
Controllable
~5GW
embedded
solar
Less
Storage
‘coming very soon’
Balancing the grid in the UK
System Operator’s role:
(1) Manage electricity flow across the networks and (2) balance generation and demand
 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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Balancing the grid in the UK
Main procured services:
 Frequency response
 Reserve (energy and system balancing)
 Constraint management
 Reactive power (voltage control)
 Intertrips
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Balancing the grid in the UK
http://www.gridwatch.templar.co.uk/
Time lapse of 12 hours of operation on 11 April 2016
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Controlling wind farm output
?
There’s plenty of
inertia available!
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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
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Above rated wind speed
Controlling wind farm output: Power increase
Below rated wind speed
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Above rated wind speed
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Controlling wind power output: shaping
 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
 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
Unit power
 A hybrid system may include a
storage device to extend overall
capability
Time [s]
Source: Generic grid frequency response capability for wind power plant E. A. Bossanyi, EWEA Annual
conference November 2015
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Forecasting (production and availability)
 Accurate forecasting is essential when providing balancing or ancillary services
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Communications for balancing and ancillary services (UK)
Transmission connected
Distribution connected (embedded)
• Real-time metering
• Real time metering possible
• Forecasts provided (physical notification)
• Accurate forecasts possible
• Control instruction system provided (dispatch)
• Control via ‘aggregation’ supported and possible
National Grid control room
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Renewables control room
Conclusion
 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:
Visible
Predictable
Controllable
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Thank you!
Keir Harman
[email protected]
+44 7990 970 141
www.dnvgl.com
SAFER, SMARTER, GREENER
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