1. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 Integration of Offshore Wind Farms into the Local Distribution Network Charles A. Lynch ca.lynch@ipsa-power.com

2. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 2 DTI Project K/EL/0272 Final Report http://www.dti.gov.uk/energy/renewables/ publications/pdfs/kel00272.pdf

3. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 3 Partners IPSA Power Ltd. EEPS Group, UMIST Innogy/National Wind Power Powergen

4. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 4 Objectives Establish viability of 100MW+ of wind generation connected to 132kV Establish validity of analysis tools for systems with doubly fed generators Compare the behaviour of the different types of wind generator Investigate using converter controls to assist is local area voltage control

5. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 5 Project Phases DFIG Model Development Steady State and Dynamic Connections Studies Optimal Power Flow Development DFIG model Voltage Control Studies

6. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 6 Generation Alternatives ‘Fixed Speed’ Induction Generator Variable Speed Synchronous or Induction Generation via Static Converters Doubly Fed Induction Generator (DFIG)

7. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 7

8. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 8 Double Fed Induction Generator What is a DFIG? Wound rotor Induction Machine Variable frequency voltage applied to the rotor windings Why is it needed? Variable speed, from about 0.7 to 1.3 per unit Optimise performance over a range of wind speeds

9. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 9 Typical configuration of DFIG wind turbine As

10. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 10 Modelling Requirements Load Flow Studies Voltage Stability and Control Variation of real and reactive power over operating regimes Fault Analysis Studies Dynamic Analysis Studies Transient and Dynamic stability

11. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 11 Modelling Detail Control Modes Speed Control plus Power Factor control Associated AC/DC Converters Two Points of Power Injection May not be explicitly modelled Rotor reactive power is not provided by the network

12. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 12

13. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 13 DFIG Performance Characteristic

14. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 14 Connection Studies Collaborators Scottish Power, Manweb United Utilities

15. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 15

16. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 16 Variable speed synchronous generation

17. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 17 Steady State Studies Fixed Speed Induction Machines Higher reactive power flows Increased voltage regulation Higher make duty fault levels DFIG Lower increase in make duty fault levels Variable Speed Synchronous Machines Least impact

18. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 18 Dynamic Analysis All three generation types modelled Fault clearance studies for faults at the wind farm and on the 132kV network Further development of controller modelling by User Defined Modelling DTI Project: K/EL/0321 Facilitating the modelling of embedded generation

19. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 19 Fault at 132kV, example 1

20. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 20 Fault at 132kV, example 2

21. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 21 User Defined Modelling

22. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 22 Voltage Control Studies Load Flow and Optimal Power Flow (OPF) studies Compare fixed speed and variable speed machines Determine optimal control strategy over a range of network conditions Coordinated area based voltage control Maximise generation penetration

23. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 23 Voltage Control Results Significant improvement operating wind farm under voltage control compared with constant power factor control (DFIG) Increased generation penetration possible Fixed speed machine power factor correction is an additional constraint OPF very helpful in addressing a wide range of issues

24. Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 24 Conclusions Alternative generation types successfully modelled in system wide studies Connection of 100+ MW of offshore generation is possible at 132kV More generation can be connected if it participates in voltage control Full report: http://www.dti.gov.uk/energy/renewables/ publications/pdfs/kel00272.pdf