Transcript Technical aspects of energy-efficient distribution

Science, Research and Development
European Commission
Technical aspects of energyefficient distribution
transformers
Frederik Groeman
7/18/2015 - 1
ENERGY, ENVIRONMENT AND SUSTAINABLE DEVELOPMENT
Science, Research and Development
European Commission
Technical aspects of energyefficient transformers
• Energy efficiency of distribution
transformers
• Technological feasibility of energy-efficient
transformers
• Economics of energy-efficient transformers
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Distribution transformer
efficiency standards
Load Losses for Distribution Transformers
RATED
POWER
OIL-FILLED (HD428) UP TO 24kV
LIST A
kVA
50
100
160
250
400
630 /4%1)
630 /6%
1000
1600
2500
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W
1,100
1,750
2,350
3,250
4,600
6,500
6,750
10,500
17,000
26,500
LIST B
W
1,350
2,150
3,100
4,200
6,000
8,400
8,700
13,000
20,000
32,000
2)
LIST C
W
875
1,475
2,000
2,750
3,850
5,400
5,600
9,500
14,000
22,000
DRY TYPE
(HD538)
12kV
PRIMARY 3)
W
N/A
2,000
2,700
3,500
4,900
7,300
7,600
10,000
14,000
21,000
No-Load Losses for Distribution Transformers
OIL-FILLED (HD428) UP TO 24kV2)
LIST A’
W
190
320
460
650
930
1,300
1,200
1,700
2,600
3,800
LIST B’
W
145
260
375
530
750
1,030
940
1,400
2,200
3,200
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LIST C’
W
125
210
300
425
610
860
800
1,100
1,700
2,500
DRY TYPE
(HD538)
12kV
PRIMARY 3)
W
N/A
440
610
820
1,150
1,500
1,370
2,000
2,800
4,300
Source: CENELEC
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Standard transformer losses
at full load - HD 428 (538)
3.0%
2.5%
2.0%
A-A'
C-C'
Dry type
1.5%
1.0%
0.5%
0.0%
100
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160
250
400
630
1000
1600
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2500
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Energy losses in distribution
transformers
•
•
•
•
•
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Dependent on design and use
No-load losses (“iron losses”)
Load losses (“copper losses”)
Standard levels in HD 428 A-A’…C-C’
A mixed population throughout Europe
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Efficient transformer designs
• No-load losses
– core material (e.g. high-grade steels, amorphous)
– core section
– core design
• Load losses
– increased conductor section
– lower temperature
• Even the lowest HD428 loss level does not
require technical specialties
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Building distribution transformers
more energy-efficient?
No big  problem!
7/18/2015 - 7
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From “nameplate” losses to
actual losses:
the effect of loading
7/18/2015 - 8
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From “nameplate” losses to real
energy losses
• No-load losses (“iron losses”)
– voltage dependent
– always present, 8760 hours per year
– 1 kilowatt no-load loss  8760 kWh per year
• Load losses (“copper losses”)
– load dependent
– kilowatt load loss  e.g. 2000 kWh per year
• Load: power factor, harmonics
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Transformer efficiency
100%
99%
98%
97%
96%
95%
94%
93%
400 kVA,
efficiency
level A-A’
(HD428)
92%
91%
90%
0%
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25%
50%
75%
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100%
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Efficiency @ low load
100%
95%
90%
400 kVA,
efficiency
level A-A’
(HD428)
85%
80%
75%
0%
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5%
10%
15%
20%
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25%
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Examples of loaded transformers
100 kVA transformer
400 kVA transformer
• A-A’
• A-A’
– nameplate: 97.7%
– yearly basis: 94.7%
• C-C’
• C-C’
– nameplate: 98.1%
– yearly basis: 96.5%
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– nameplate: 98.5%
– yearly basis: 98.0%
– nameplate: 98.8%
– yearly basis: 98.6%
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Energy-efficient application of
distribution transformers
• Match the transformer design
to the load:
– peak load
– running time of peak load
• Avoidance of over-excitation
• Always a compromise
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Economic aspects
• A balance between purchase cost and
energy losses
• Loss evaluation as an alternative to
standard loss values
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Loss evaluation
• Purchase costs
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• Load losses
• No-load losses
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Capitalised cost of a transformer
CC = Ct + A·Po + B·Pk
Application data
• A: cost no-load losses (€/W)
• B: cost of load losses (€/W)
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Transformer data
• Ct: purchase price (€)
• Po: no-load loss (W)
• Pk: load losses (W)
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Application of capitalised cost
• Selection of the “best” (cheapest) transformer
• A and B reflect NPV of purchase costs of
energy for the owner
• B also reflects the load pattern
• Low A/B values favour cheap transformers
• High A/B values favour efficient transformers
• The European standards leave some freedom
for deviations
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A and B values for selected
countries
Euro / Watt
Netherlands
Germany (86)
Germany (93)
CH
China
Sweden
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A (NLL)
4.0
4.0
11.3
7.5
5.0
4.0
B (LL)
1.2
1.0
4.0
1.9
0.7
0.5
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Two 400 kVA designs
A-A’
C-C’
Price
4.4 k€ 4.9 k€ (+11%)
L os s c os t 9 . 2 k € 7 . 1 k €
Net cost 13.6 k€ 11.9 k€ (-12%)
No-load losses 4 €/W, load losses 1.2 €/W
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Conclusions
• Efficiency can be significantly increased at a
price premium
• Fit transformers to their load
• Losses are typically as expensive as the
transformer itself
• Kyoto commitments
• Take lifetime costs into account, not just first
costs
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