Transcript The Australian ESI

MEPS 2 - The Next Stage of
Efficiency Regulation for
Distribution Transformers
Trevor Blackburn
School of Electrical Engineering
UNSW
The Role and Purpose of
MEPS Regulations
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Improve power and energy efficiency levels
Reduce electrical energy waste and CO2 emissions
Done by regulating minimum efficiency levels
Applied to locally-manufactured and imported items
Electrical equipment regulated by MEPS include:
– Distribution transformers
– Large electrical drives
– Air conditioners
– Fluorescent ballasts
– Compact fluorescents
The MEPS regulation process
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Public domain technical report issued
Discussions with manufacturers and users
Regulatory Impact Statement generated
Australian Standard developed and published
Applications for registration and approval for
specific classes of transformers
• Compliance testing process
Distribution Transformer Range
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Single phase and three phase
Ratings: 10 kVA – 3100 kVA (2500 now)
Includes: oil-filled, dry-type and SWER units
MEPS 1
– Introduced in 2004
– Two minimum power efficiency levels specified
• Standard
• High efficiency
[Regulated minimum levels]
[Voluntary levels]
• MEPS 2
• Proposed implementation date of no earlier than
– 2012
– One regulated minimum efficiency level is specified
• Identical to the MEPS 1 high efficiency level
Why Transformers?
• Network losses are significant
– Represent about 5-10% of overall T & D energy
transfer
• Network Transformers
– Cause up to 40% of total network losses
• Between the generator and consumer at
400/230 V, electrical energy may pass
through:
– 2 transmission transformers
– 2 or 3 distribution transformers
Distribution losses in Australian utilities
2009 [ESAA – EGA data]
Transmission & Distribution
transformer regulation ?
• Transmission transformers
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Usually one-off design
Usually very energy efficient
Very small numbers
Give only limited energy saving benefits
• Distribution transformers
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Mass produced to an economic design
Losses may be sacrificed for low capital cost
Very large numbers in use
Potentially large energy saving benefits
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Number of utility-owned Distribution
Transformers in Australia: 2010
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33 kV
22 kV
11 kV and below
SWER
• TOTAL
7,544
213,373
337,759
113,248
661,934
• Usually relatively lightly loaded (25-30%)
• Long life expected
Number of privately owned transformers
(commerce, industry, mines)
• Difficult to determine
• Large numbers of imported units
• Based on international numbers, about
25% of utility numbers
• Generally shorter life than utility trafos
• More heavily loaded:
– About 40-50% on average
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Transformer loss and
greenhouse gas mitigation
MEPS for Transformers
AS 2374.1.2 - 2004
Power transformers – Part 1.2
Minimum efficiency Performance
Standards (MEPS) requirements for
Distribution Transformers
Specifies minimum (power) efficiency levels
for oil and dry-type transformers under
specific test conditions
Existing MEPS efficiency Levels
Liquid-immersed transformers
(at 50% rated load)
Existing MEPS Levels
Dry-type transformers
[at 50% rated load]
Effect of loading on losses
Targosz_2007
(Leonardo)
MEPS 2 Levels
Why do we need to increase
MEPS1 efficiency levels to MEPS2?
• Need the most efficient transformers that are
available to minimise the effect on climate change
• Power electronic loads on transformers will increase
losses due to harmonic content:
– Increasing harmonic levels arise from use of:
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Adjustable speed drives (IGBT switching)
Switch mode power supplies (Computers and IT equipment)
Compact fluorescent lamps
Any other non-linear loading
– Transformer losses scale as the square of
harmonic number
• May require de-rating of transformers in some applications to
avoid overheating
• K-factor transformers
Energy savings with MEPS 2
1000 kVA oil filled transformer
• Daily load cycle
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8 hours @ full load, unity PF
6 hours @ 50% load, unity PF
6 hours @ 25% load, unity PF
4 hours @ no load
• MEPS 1 power efficiency = 99.27%
• MEPS 2 power efficiency = 99.37%
Energy savings potential
• MEPS 1efficiency
– Daily energy efficiency:
– Daily energy loss:
99.07%
117 kWh
• MEPS 2 efficiency
– Daily energy efficiency:
– Daily energy loss:
99.24%
100 kWh
• Daily energy saving with MEPS2
• Annual saving with MEPS 2:
17 kWh
6.21 MWh
• Annual CO2 saving:
6.42 tonnes
Effect of non-linear loads
• Both core loss and load loss are
increased by harmonic frequency
content of the load current and/or
supply voltage
• Core loss
– Hysteresis loss scales as
(f)1.8
– Eddy current loss scales as (f)2
• Copper eddy current loss scales as (f)2
Adjustable speed induction drive
harmonics
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CFL Current Harmonics
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Effect of harmonic loss
150 kVA transformer supplying PCs
Requires de-rating to 125 kVA to maintain normal life
Can the efficiency levels of
transformers be increased?
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What are the ultimate efficiency limits?
What are the manufacturing constraints?
New materials?
What are the operational constraints?
Industrial use and impact on losses
Total life cycle cost of the transformer
The ultimate efficiencies
[US DOE determination : MAX-TECH levels]
Comparison of MEPS1 with other international efficiencies for
liquid immersed three phase transformers
Efficiency Comparison: 3 phase liquid
100
99.8
99.6
Power efficiency (%)
99.4
99.2
MEPS1
US benchmark
US proposed
EU existing
EU proposed
Japan top runner
99
98.8
98.6
98.4
98.2
98
97.8
50
100
160
250
400
630
1000
1600
2500
Transformer rating (kVA)
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Comparison of MEPS1 [12 and 24 kV] with other international efficiencies
for dry-type three phase transformers
Efficiency comparison: 3 phase Dry type (12 kV)
100
99.5
Transformer efficiency (%)
99
MEPS1 12 kV
US Benchmark
US Proposed
EU HD528
Japan top runner
MEPS1 24kV
98.5
98
97.5
97
96.5
50
100
160
250
400
630
Transformer Rating (kVA)
1000
1600
2500
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Comparison of MEPS1 And MEPS2 liquid immersed transformer
efficiencies with international standards
Oil Tx comparison
100
99.8
99.6
99.4
99.2
MEPS1
US benchmark
US prop
EU C-C'
EU pr
Japan
MEPS2
99
98.8
98.6
98.4
98.2
98
97.8
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2
3
Australian
ESI5 Aug 07 6
4
7
8
9
27
New MEPS comparison
MEPS1 and MEPS2 efficiencies for all transformer types and ratings
MEPS1 and MEPS2 Transformer Efficiencies
100
99.5
Power Efficiency @ 0.5 pu (%)
99
Oil 1ph_MEPS1
Oil 3ph_MEPS1
Oil 1ph_MEPS2
Oil 3ph_MEPS2
Dry(12kV) 1ph_MEPS1
Dry(12kV) 3ph_MEPS1
Dry(12kV) 1ph_MEPS2
Dry(12kV) 3ph_MEPS2
98.5
98
97.5
97
96.5
96
10
16
25
50
25
63Australian
100
200
ESI
315Aug
50007 750
Transformer Rating (kVA)
1000 1500 2000 2500
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Increase in transformer numbers and installed capacity for the 30 year
modelling period [2006 – 2036].
Increase in Transformer Number and capacity 2006-20036
1400000
1200000
Number and MVA
1000000
800000
Utility Tx no.
Utility Tx MVA
Private Tx no.
Private Tx MVA
600000
400000
200000
0
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Year
30
Annual loss of the three phase oil-immersed transformers with MEPS1 and
MEPS efficiency and the difference in annual loss [at 25% load]
Annual energy loss @ 25% load for 3 ph oil units with MEPS1 and MEPS2
45000
40000
35000
Energy loss (kWh)
30000
25000
3 ph MEPS1
3 ph MEPS2
MEPS1-MEPS2
20000
15000
10000
5000
0
25
63
100
200
315
500
Rating (kVA)
750
1000
1500
2000
2500
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Timeline for MEPS 2
• Dec/Jan2008: Broad elements of new
standard containing revised figures
• April 2012: Likely Public Comment
Draft of new Standard to be produced
• 2013: MEPS 2 to be implemented no
earlier than this
Efficiency determination
• NATA registered labs for MEPS for
Transformers
• TCA
• CalTest
(Sydney)
(Port Elliott, SA)
• CalTest also test Motors to MEPS
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Manufacturer Tests
• Australian Manufacturers perform loss
measurements and efficiency determination
as a type test.
• Main manufacturers for utilities are
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Wilsons
(Wodonga)
Schneider (Benalla)
Tyree
(Mittagong)
ABB
(Brisbane and Perth)
TMC
(Melbourne)
Ampcontrol (Newcastle)
Australian ESI Aug 07
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Imported transformers
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Very large numbers
Mainly for the private sector
Difficulty in regulating
Testing is difficult because of size
Need mobile test sets
– Caltest have mobile facility
– Excite from LV side
– Problems with OHS constraints
Australian ESI Aug 07
35
Efficiency determination
• Method used in the Standard is from the main
power trafo standard: based on loss
compliance tests
• Requires only 1-2% accuracy in loss
determination
• But efficiency is specified to a 0.01% variation
• Uncertainty of the efficiency determination is
thus questionable
• US Dept of Energy has a much more rigorous
test method specified
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Conclusions
• Transformers are a significant contribution to
overall network loss
• There is significant potential for reduction of
transformer losses
• Modern load types increase losses due to the
high harmonic content
• Harmonics should be included in some form
in testing
• Testing methods as specified need some
improvement