DS2 – Grid Integration Dynamic Modelling of Wind Generation in Ireland Margaret Riordan ESB National Grid, Ireland (email: Margaret.Riordan@EirGrid.com tel: +353-1-7026941 fax: +353-1-6615375) Co Authors – Jane McArdle & Yvonne Coughlan

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

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

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 MW Min (Summer) 1,735 MW

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

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 2002. 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.

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

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

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

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

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.

Voltage Stability – Voltage Recovers

Voltage Stability – Voltage Fails to Recover

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

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

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

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

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

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

WTG Model Testing, Typical Issues – Initialisation

WTG Model Testing, Typical Issues – Numerical Instability

WTG Model Testing - Status Model Status Document Published on www.EirGrid.com updated regularly

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.

System Study Issues - Model Oscillations

System Study Issues - Numerical Instability

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

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

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

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

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

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

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.

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

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

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