1. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 1 TRANSFORMERS FOR WIND TURBINES NEED FOR NEW DESIGNS OR BUSINESS AS USUAL Dr. Jan Declercq

2. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 2 Grid developments … today EHV transmission Generation 100 MW >220 kV Transmission Sub-transmission 110 – 70 kV Distribution 0.5-4 MW 30 kV

3. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 3 Grid developments … today EHV transmission Embedded Generation 100 MW >220 kV Transmission Sub-transmission 110 – 70 kV Distribution 0.5-4 MW 30 kV Overloading, power quality, economics, environment, maintenance, reliability

4. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 4 Types of distribution transformers Mineral oil filled transformers Cast resin transformers SLIM ® technology silicon oil and aramid insulation

5. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 5 Distribution Transformers Mineral oilCast ResinSLIM ® –Power in MVA 0.5..10..5000.5..101..10 –High voltage kV10..36..50010..33 10..36.. –Low voltage V 400..6300..400..3000 400..3000 –Impedance 4..10..25 4..85..10 Same operating range of voltages and power What about other specifications?

6. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 6 Distribution Transformers –No load losses and load losses –Dimensions –High load, ambient temperature and harmonics –Environmental issues –Fire behavior –Enclosures and cable boxes –Vibrations

7. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 7 Fit the door

8. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 8 No load losses, load losses, Dimensions No load losses –Ex. 2 kW * 8760 h/y * 0.05 EUR/kWh Load losses –Ex. 18 kW*Load factor 2 * 0.05 EUR/kWh*duration so important how long and load level –Heat dissipation in turbine or substation Dimensions –Mass for nacelle installation –Flexibility to install, “fits the door” –Option to replace

9. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 9 High load, ambient temperature and harmonics Maximum allowable temperatures depend on insulation material –Mineral oil, cellulose 100°C –Cast Resin 155°C –Silicon oil 150°C, aramid insulation 200°C Maximum operating temperature depend on –Ambient temperature for transformer !! –Load and duration –Harmonic content Transformer specification –Ex. 60 K rise at full load and 30°C leads to 90°C

10. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 10 High load, ambient temperature and harmonics Load P Current I Losses RI 2 Temperature

11. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 11 High load, ambient temperature and harmonics Load P Current I Losses RI 2 Temperature Lifetime T ins 100 C

12. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 12 On-site measurements of thermal performance of a 2 MVA SLIM  transformer in a windturbine

13. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 13 Results and discussion Power in period 1

14. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 14 Results and discussion Temperatures in period 1

15. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 15 Fire behavior Depend on standards, laws, policies, habits no strict guidelines for windturbines Transformers not treated active to fire –Source : do not start fire themselves good reputation –Victim : depends on material Technical specifications Mineral oil class O (fire point 150 C) Silicon oil class K3 (fire point 360 C ) Cast resin classes F0, F1 (similar numbers)

16. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 16 Vibrations Transformers designed for transport accelerations up to 3 g Wind turbine specifications accelerations <1 g, continuous and <100 Hz

17. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 17 Increased failures Much more voltage fluctuations due to step up Sharp load fluctuations (1 to 100 % in 1 minute) Fast Transient overvoltages between CB and transformer (increased number of failures in Scotland and Denmark. Cigre 12-15 WG) More than 50 switching events per year Increased average loading and harmonics Vibrations Moisture Remote locations, reduced maintenance

18. DECLERCQ Jan BE Alpha 4 – Block 2 Barcelona 12-15 May 2003 18 Increased failures Multiple transformers went on fire, even dry type On average 30 % more failure rate No possibility for replacement Long time for restart