1. DS2 – Grid Integration Dynamic Modelling of Wind Generation in Ireland
Margaret Riordan
ESB National Grid, Ireland
( tel: fax: )
Co Authors – Jane McArdle & Yvonne Coughlan

2. 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

3. 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

4. Overview of the Irish Transmission System
Small Island system
Approximately kV lines
Approximately kV lines
2 400kV lines
Present system demand records are:
Peak (Winter) 4,823 MW
Min (Summer) 1,735 MW

5. Overview of the Irish System - Interconnection
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
450 MW HVDC
IRELAND
ENGLAND
SCOTLAND
WALES DC

6. Wind Generation - Penetration in Ireland
Status
February 2005 MW
Cumulative
(MW)
% of Winter Peak 2010
(% of 5515 MW)
Connected
493 9%
Contracted
665
1158
21%
Offers
125
1283
23%
~Applications
2869
4152
75%
320MW
Connecting in 2006
of 4,238 MW was reached in forecast to be 5600 in 2010 – value dies not include house load of Generators.
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.

7. 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

8. 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

9. Transient Stability
220 kV fault lasting 100 ms close to a large generator

10. Transient Stability
220 kV fault lasting 150 ms close to a large generator

11. 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.

12. Voltage Stability – Voltage Recovers

13. Voltage Stability – Voltage Fails to Recover

14. 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

15. 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
After testing the models that had been developed at this time, it was found that they didn’t perform satisfactorily.
Available Models
Comments 1
Incomplete 2
60Hz version only 3

16. 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 models
It 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
3 models were available to us, US 60 Hz a WTG manufacturer and a BIWTP models

17. Work to Date – Model Features
Most dynamic models received represent some or most of the following features:

18. Siemens / Bonus Enercon GE / Enron Gamesa DE Wind Nordex
WTG Model Testing
23 WTG models, 7 different manufacturers
Improvements have been made to the models, but work still remains to be done
Siemens / Bonus
Enercon
GE / Enron
Gamesa
DE Wind
Nordex
Vestas / Neg Micon

19. Initialise simulation Select output channels
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
Model tests

20. WTG Model Testing, Typical Issues – Initialisation

21. WTG Model Testing, Typical Issues – Numerical Instability

22. WTG Model Testing - Status
Model Status Document
Published on updated regularly

23. 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.

24. System Study Issues - Model Oscillations

25. System Study Issues - Numerical Instability

26. 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

27. 0.1s following fault clearance
System Studies - 200ms close proximity severe 110kV fault
110 kV busbar
90%V
Recovery to 90% V
0.1s following fault clearance
No Wind Generation
Recovery to 90% V
5.1s following fault clearance

28. System Studies - 200ms close proximity severe 110kV fault
110 kV Busbar
90%V
Wind Generation
Recovery to 90% V
1.3s following fault clearance
Recovery to 90% V
5.1s following fault clearance

29. Individual Connection Assessments
Timeline
320 MW connecting in 2006
Dynamic model suitable for
Connection offer process
Grid Code compliant model
120 days prior to connection
Application
Accepted
Offer
120 days
Connected

30. 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

31. 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

32. Next Steps – Model Validation
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.

33. 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

34. Next Step Model Validation
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

35. Questions Thank you for your attention www.eirgrid.com
Further information