national grid ds2 – grid integration dynamic modelling of wind generation in ireland margaret...
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NATIONAL GRID
DS2 – Grid Integration
Dynamic Modelling of Wind Generation in Ireland
Margaret Riordan
ESB National Grid, Ireland(email: [email protected] tel: +353-1-7026941 fax: +353-1-6615375)
Co Authors – Jane McArdle & Yvonne CoughlanESB National Grid, Ireland
NATIONAL GRID
Presentation Overview
Background– Irish Transmission System– Wind Penetration– Dynamic Analysis
ESBNG Work to Date– Dynamic Modelling– Model Features– Model Testing– System Studies– Connection Studies
Next Steps
Summary
NATIONAL GRID
Presentation Overview
Background– Irish Transmission System– Wind Penetration– Dynamic Analysis
ESBNG Work to Date– Dynamic Modelling– Model Features– Model Testing– System Studies– Connection Studies
Next Steps
Summary
NATIONAL GRID
Overview of the Irish Transmission System
Small Island system Approximately 200 110kV lines Approximately 50 220kV lines 2 400kV lines
Present system demand records are:Peak (Winter) 4,823 MWMin (Summer) 1,735 MW
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Overview of the Irish System - Interconnection
450 MWHVDC
IRELAND
ENGLAND
SCOTLAND
WALES
DC
Lightly interconnected to Northern Ireland– Typical North South
Interconnector flows ~100MW
– Total AC System winter peak ~ 6500MW
Northern Ireland has a DC interconnection with UK
NATIONAL GRID
Wind Generation - Penetration in Ireland
Status
February 2005
MW Cumulative
(MW)
% of Winter Peak 2010
(% of 5515 MW)
Connected 493 493 9%
Contracted 665 1158 21%
Offers 125 1283 23%
~Applications 2869 4152 75%
320MW Connecting in 2006
European Union Renewable Directive Target for Ireland is 13.2% of electricity from renewable sources by 2010.This requires about 9% from wind ≈ 1,000 MW installed.
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Importance of dynamic modelling in power systems
ESBNG is committed to facilitating the continuing growth of wind power while safeguarding system security for all electricity customers
To safeguard system security, dynamic analysis to predict the performance of the system under a wide range of conditions is required
The transient stability and voltage stability of the system are of particular concern
NATIONAL GRID
Transient Stability – What is it?
During a fault close to a generator, the generator can’t export its power. Therefore it speeds up.
When the fault clears, it should slow down to synchronous speed.
A generator may not re-synchronise with the others if there is a transient stability problem
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Machine Speeds
-0.006
-0.004
-0.002
0
0.002
0.004
0.006
0.008
0.01
0.012
0 0.5 1 1.5 2 2.5
Time (Seconds)
Sp
ee
d (
pu
)
Transient Stability
220 kV fault lasting 100 ms close to a large generator
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Machine Speeds
-0.02
0
0.02
0.04
0.06
0.08
0.1
0.00 0.50 1.00 1.50 2.00 2.50
Time
Sp
ee
d (
pu
)
Transient Stability
220 kV fault lasting 150 ms close to a large generator
NATIONAL GRID
Voltage Stability – What is it?
Ability of the system voltage to recover following a disturbance.
Large induction machines (motors and generators) tend to inhibit voltage recovery.
During the fault, generators accelerate Once the fault is cleared, they will try to slow down In slowing down, they take reactive power from the
network; this tends to pull the voltage down.
NATIONAL GRID
Voltage
0
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0.8
1
1.2
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Voltage Stability – Voltage Recovers
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Voltage
0
0.2
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1
1.2
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Voltage Stability – Voltage Fails to Recover
NATIONAL GRID
Presentation Overview
Background– Irish Transmission System– Wind Penetration– Dynamic Analysis
ESBNG Work to Date– Dynamic Modelling– Model Features– Model Testing– System Studies– Connection Studies
Next Steps
Summary
NATIONAL GRID
Work to Date - Dynamic modelling
Due to the high level of wind generation in Ireland dynamic analysis now must include windfarms, requiring the development of wind turbine models
Prior to December 2003 PSS/E (software package widely used to carry out system
analysis worldwide) did not contain any suitable models for wind, either in its libraries or as user written code
Available Models
Comments
1 Incomplete
2 60Hz version only
3 Incomplete
After testing the models that had been developed at this time, it was found that they didn’t perform satisfactorily.
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Work to Date - Dynamic modelling
Requested WTG manufacturers to provide dynamic modelling information
Published a document outlining the need for dynamic models and a brief description of what is required in the modelsIt also included a brief overview of what studies were to be carried out once the models were received
Updated the Grid Code to include a section on Wind Dynamic Modelling Requirements
Obtained and tested numerous models
Ongoing work on Model Validation, Testing, System Studies and Individual Connection Assessments
NATIONAL GRID
Work to Date – Model Features
Most dynamic models received represent some or most of the following features:
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WTG Model Testing
23 WTG models, 7 different manufacturers Improvements have been made to the models, but
work still remains to be done
NATIONAL GRID
ESBNG Request for models
Model Received
Request for additional Information
Assess Package Contents
Set up dynamic analysis for modeltesting
Set up with 1 WTG
Carryout dynamic analysis of model
Set up with 10 WTG
Carryout dynamic analysis of model
Model Behaviour seems reasonable
Testing and Progress
Model Testing Process
Check for steady state
Set up load flow case
Associate dynamic models and parameters with case
Compile and link models
Initialise simulation
Select output channels
Apply a disturbance
Analyse results
121 times
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WTG Model Testing, Typical Issues – Initialisation
0.197
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0.2
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0.204
0.205
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Time (sec)
Po
wer
(p
u o
n s
yste
m b
ase)
1.047
1.048
1.049
1.05
1.051
1.052
1.053
1.054
Vo
ltag
e (p
u)
Test Model's Active Pow er Voltage at 110kV connection point
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WTG Model Testing, Typical Issues – Numerical Instability
0
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0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Time (sec)
Po
wer
(p
u o
n s
yste
m b
ase)
Active Pow er w indfarm 1 Active Pow er w indfarm 2
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WTG Model Testing - Status
Model Status Document
Published on www.EirGrid.com updated regularly
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System Study - Assumptions
605 MW Wind Generation included in study
Windfarms included utilise 18 different turbines, due to certain models being unsuitable or unavailable, studies were carried out with 12 different models
Trial study highlighted issues such as:– Sustained Oscillation– Numerical Instability
with some of the models, so they were removed and the studies re-run using 5 different models.
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System Study Issues - Model Oscillations
0.041
0.0415
0.042
0.0425
0.043
0.0435
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Time (sec)
Po
wer
(p
u o
n s
yset
m b
ase)
Test Model's Active Pow er
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System Study Issues - Numerical Instability
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0
Time (sec)
Rea
ctiv
e P
ow
er (
pu
on
sys
tem
bas
e)
0.035
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0.039
0.04
0.041
Act
ive
Po
wer
(p
u o
n s
yste
m b
ase)
Test Model's Reactive Pow er Test Model's Active Pow er
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System Studies - Update
Currently Suspect models removed, case now contains 5
different models Compiling Report from Phase I work completed Preliminary results depict possible voltage Issue
Future Development of scope of work for Phase II
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System Studies - 200ms close proximity severe 110kV fault
No Wind Generation
110 kV busbar
90%V
Recovery to 90% V 0.1s following fault clearance
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System Studies - 200ms close proximity severe 110kV fault
110 kV Busbar
90%V
Wind Generation
Recovery to 90% V 1.3s following fault clearance
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Individual Connection Assessments
Timeline
320 MW connecting in 2006
Application AcceptedOffer 120 days Connected
Grid Code compliant model120 days prior to connection
Dynamic model suitable for Connection offer process
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Individual Connection Assessments
All connected windfarms are included in the study
Only problems caused by the connection of the windfarm are associated with it.
Although models currently contain some limitations they are being used for carrying out some initial wind farm connection studies, through use of various workaround techniques
To date there have been no issues
NATIONAL GRID
Presentation Overview Background
– Irish Transmission System– Wind Penetration– Dynamic Analysis
ESBNG Work to Date– Dynamic Modelling– Model Features– Model Testing– System Studies– Connection Studies
Next Steps
Summary
NATIONAL GRID
It is important that the behaviour shown by the model under simulated conditions is representative of the behaviour of the real equipment under equivalent conditions
The confidence with which simulated results can be viewed is dependent upon the quality of the validation material provided by the manufacturers
ESBNG plan to engage in further dialogue and consultation with manufacturers, developers and any other relevant stakeholders with a view to adopting a more coordinated and focussed approach to wind turbine model validation.
Next Steps – Model Validation
NATIONAL GRID
Presentation Overview Background
– Irish Transmission System– Wind Penetration– Dynamic Analysis
ESBNG Work to Date– Dynamic Modelling– Model Features– Model Testing– System Studies– Connection Studies
Next Steps
Summary
NATIONAL GRID
Summary
ESBNG have Obtained and Tested 23 WTG models, 5 of which are now suitable for the full system studies
ESBNG would like to pay tribute to the turbine manufacturers work to date while also highlighting that there is a large amount of work still to be done
ESBNG are running a system study with a number of working models to assess the dynamic impact of high levels of wind generation on the Irish power system
Next Step Model Validation
NATIONAL GRID
Questions
Further information
www.eirgrid.com
Thank you for your attention