Science, Research and Development European Commission 4/30/2020 - 1

Energy Efficient Distribution Transformer Solutions

Raymond Van Schevensteen Pauwels Trafo Belgium

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 2 Science, Research and Development

Design concepts

• Optimised design parameters are determined by:

– Technical specifications – Base material prices – Transformer load profile • Loss-values or loss-evaluation  Iron/copper balance – Labour cost

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT European Commission

Science, Research and Development European Commission

Design concepts improve efficiency



Improve efficiency via no-load losses (Po)

– Selection of type of

Magnetic Steel

– Selection of

Cutting Pattern

– Reduce

Flux density

(increase section) 

Improve efficiency via load losses (Pk)

– Selection of

conductor material Cu-Al and shape

– Reduce

Current Density

(increase section) 

More or better material - extra cost

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT 4/30/2020 - 3

4/30/2020 - 4 Science, Research and Development

Historical evolution in the production of magnetic steel

YEAR (approx.) 1895 1910 1950 1960 1965 1970 1975 1980 1983 1985 1987 1991 CORE MATERIAL THICKNESS (mm) Iron wire Warm rolled FeSi Cold rolled CGO Cold rolled CGO Cold rolled CGO Cold rolled HiB Amorphous metal Cold rolled CGO Cold rolled HiB Laser treated HiB Cold rolled CGO Plasma treated HiB Chem.Etched HiB 0.35

0.35

0.3

0.27

0.3

0.03

0.23

0.23

0.23

0.18

0.23

0.23

EPSTEIN VALUE (W/kg at 50Hz) 6 (1.0T) 2 (1.5T) 1 (1.5T) 0.9 (1.5T) 0.84 (1.5T) 0.8 (1.5T) 0.2 (1.3T) 0.75 (1.5T) 0.70 (1.5T) 0.6 (1.5T) 0.67 (1.5T) 0.6 (1.5T) 0.6 (1.5T) TYPE M6x M5x M4x M0H M3x M0H ZDKH M2x Plasma PJ PDR European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development Evolution of magnetic steel since the introduction of cold-rolled magnetic steel European Commission 4/30/2020 - 5 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development Cold rolled Grain Oriented magnetic steel (GO) : • Cold rolling process allows recrystallization, having grains aligned almost parallel to the rolling direction • Fe +3% Silicon for reduction of electric conductivity • Double insulating coating European Commission 4/30/2020 - 6 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 7 Science, Research and Development Minimal properties of CGO according to IEC 60404-8-7 GRADE M127-23S 5 M140-27S 5 M150-30S 5 M165-35S 5 THICKNESS Maximum specific total loss (W/kg) at 50Hz and (mm) 0.23

0.27

0.30

0.35

1.5T

0.80

0.89

0.97

1.11

1.7T

1.27

1.40

1.50

1.65

Minimum magnetic flux density for H=800A/m 1.75

1.75

1.75

1.75

Minimum stacking factor 0.945

0.950

0.955

0.960

Crystallographic characteristics : • Average deviation from ideal orientation : 6 to 7 o • Average diameter of magnetic grains : 2 to 3 mm European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 8 Science, Research and Development Minimal properties of HiB according to IEC 60404-8-7 GRADE M103-27P 5 M105-30P 5 M111-30P 5 M117-30P 5 M125-35P 5 THICKNESS (mm) 0.27

0.30

0.30

0.30

0.35

Maximum specific total loss (W/kg) at 50Hz and 1.7T

1.03

1.05

1.11

1.17

1.25

Minimum magnetic flux density for 1.88

1.88

1.88

1.85

1.88

Minimum stacking factor 0.950

0.955

0.955

0.955

0.960

Crystallographic characteristics : • Average deviation from ideal orientation : 3

•

Stress Coating = favourable influence on : o • Average diameter of magnetic grains : 15 to 20 mm - the specific losses - the magnetostriction European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development European Commission

Domain refining of HiB saves 15% core loss

(ZDKH, PJ, PDR, Trancor H, …) 4/30/2020 - 9 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development

Multi step-lap (automated)

European Commission 4/30/2020 - 10 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development European Commission 4/30/2020 - 11

The Ultimate Performer

Amorphous Metal

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development European Commission

Hysteresis curves CGO versus amorphous metal

4/30/2020 - 12 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 13 European Commission Science, Research and Development

Technical comparison

Thickness Density Saturation Lamination factor Stress sensitivity Annealing mm kg/dm³ Tesla % No-load losses Coating % CGO M5x 0.30

7.65

2.04

96 low limited benefit DR HiB 0.23

0.23

7.65

2.04

94.8

low forbidden 100 2 sided Carlite 65 2 sides stress amorphous ribbon 0.025

7.18

1.56

88 high field annealing compulsary 25 none ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development

Production of amorphous metal

European Commission Production of a single-phase amorphous transformer ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT 4/30/2020 - 14

Science, Research and Development European Commission

Three-phase transformer with 4 wound cores (4 cores / 5 legs)

4/30/2020 - 15 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 16 Science, Research and Development European Commission

Results of using amorphous metal cores

*

no-load losses : only 25% of a normal unit * maximum efficiency * load losses and impedance : as per specification * “normal” no-load current and inrush * “normal” noise level (as list A’ of CLC HD428) * longer and heavier * thermally overdimensioned ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 17 Science, Research and Development European Commission Typical characteristics of amorphous ribbon & AMDT design

      

Sole supplier of ribbon and cores = Allied Signal Preference to use copper-conductors

(= smaller core window).

Core saturation at 1.56T

(CGO=2.04T)

Pressure sensitive = windings must carry the cores Cores need to be annealed in a magnetic field Wound cores

(Powercore abandonned).

Rectangular windings.

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development 4/30/2020 - 18

CASE STUDY (1998) : 1600kVA AMDT

Loss-evaluation of Europe’s largest AMDT 1600kVA LOSSES AMDT CONVENTIONAL HD 428 C'-C No-Load 390 W 2400 W 1700 W Load 17 kW 16 kW 14 kW • • Saves 13 300 kWh/year at 70% loading compared • to a conventional standard 1600kVA • Irish energy cost = 0.07 IEP/kWh ROI = 3 years • Life-expectancy > 30 years • Savings after 30 years = 25 000 IEP ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT European Commission

Science, Research and Development

8-core assembly completed

European Commission 4/30/2020 - 19 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development

Wrapped core joint LV-side

European Commission 4/30/2020 - 20 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development

Active part seen from HV side

European Commission 4/30/2020 - 21 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 22 Science, Research and Development

CONSUMPTION OF MAGNETIC STEEL IN DISTRIBUTION TRANSFORMERS

European Commission TOTAL EUROPEAN DEMAND = some 150 000 tonnes/year

• • • • • • • • CGO

: some

70%

HiB

: some 20%

[COST = 100] [COST = 115]

D-REFINED

: some 10%

[COST = 160]

AMORPHOUS

: almost none

[COST = 200] ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 23 Science, Research and Development Over 100 000 units in service in USA and Japan since 1982 (=some 10% of the transformer market).

MAJOR OBSTACLES FOR INTRODUCING AMDT IN EUROPE • New technology of wound cores.

• Considerable change in transformer building.

• Higher initial cost • No incentives.

(premium = 25-35%) • Energy prices tend to be lowering.

.

• Reluctance of users to evaluate losses.

• Present high USD/Euro exchange rate.

European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 24 Science, Research and Development CORE STEEL : FUTURE DEVELOPMENTS • Amorphous metal : new sources.

• Amorphous metal : European Evans design.

• Domain refined HiB : alternative etching.

• CGO and HiB : thinner gauges & aim for best and constant quality.

• CGO : faster & low energy manufacturing.

• Domain refining of CGO and amorphous.

Evans design

European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 25 Science, Research and Development

CONDUCTOR MATERIALS aluminium and copper

• Cu- and Al-transformers can be built to comply to the same performance and quality standard.

• Smaller ratings are typically cheaper with copper windings.

• In general, the use of copper leads to : - heavier but less voluminous windings; - a smaller core; - a smaller, more compact transformer; - a lower noise level; - less oil-content.

European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

Science, Research and Development The windings of oil-immersed distribution transformers



Low voltage windings = foil- or sheet winding



High voltage windings oil-immersed type = continuous layer winding



High voltage winding dry-type = disc-winding European Commission 4/30/2020 - 26 ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 27 Science, Research and Development CONDUCTORS : FUTURE DEVELOPMENTS • Continuous Casting & Rolling process of wires (allowing for much longer lengths).

• Wide sheet & foil.

• Continuous cold rolling of strips (more consistent quality than drawn strip).

• Optimized shape (improved FF).

• Coated foils (insulating coating).

• Continuously transposed cable.

• High performance enamels (high temperature, oil-compatibility, environmental aspects, Partial Discharges, Fast Transients, …) European Commission ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 28 Science, Research and Development European Commission OTHER MATERIALS : FUTURE DEVELOPMENTS • High-temperature applications.

• Superconducting (traction) transformers.

• Flame-proof liquids & vegetable oils.

• Dry-type transformers.

• Synthetic insulating materials.

• Environmental-friendly painting systems (solvent-less, water-based, powder, …).

• Compact substations.

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT

4/30/2020 - 29 Science, Research and Development European Commission

CONCLUSIONS



Building high efficiency transformers with extreme low losses is no longer a technical challenge : C-C’ can be built using common techniques.



The final choice is purely financial.



Transformer manufacturers strive to offer additional commercial advantages (compactness, low noise, loadability, mass, …).



Amorphous metal cores combined with copper windings result in the ultimate performer.

ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT