Transcript Slide 1

Identifying opportunities to improve the
efficiency of power transmission through
existing Overhead Power Lines
Konstantinos Kopsidas
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Structure of the Presentation
• Basics of Ampacity & Sag
• Holistic Computational Methodology for
Rating an OHL
• Analysis/Comparison of AAAC & ACSR
Conductors on an 33kV OHL system
• Advanced conductors on the 33kV system
• Conclusions - The Way Forward
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Basics of Ampacity & Sag
Ampacity = The amount of current a
conductor can carry without
exceeding a specified temperature
i
i
R R
Increase
Increase
in in
conductor
conductor
temperature
temperature
heat
heat
IMAX is defined by the max conductor temperature
or the max conductor elongation
set by the operator
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Basics of Ampacity & Sag
Tension
MCT
SPAN
Sag
Increase
tension
Sag
max
Sagatatmax
electrical
electrical
loading
loading
Plastic
elongation
Conductor
initial
length
Conductor
initial length
Conductor
initial length
Minimum clearance
to ground
Sag at max
mechanical
loading
Plastic
Plastic
elongation
Elastic elongation
ElasticThermal
elongation
re-tensioning
Sag after
elongation
elongation
Elastic
the conductor
elongation
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Computational Methodology
OHL
Data
Weather
Data
Operational
Data
Conductor
Data
Maximum conductor
tension (MCT)
At specified Load
Newton-Raphson iteration of
Change of State Equation
Conductor Tension & Sag
At TOPERATING (oC)
Mechanical computation
Conductor RAC
at TOPERATING & ƒSYSTEM
IEEE 738 Std
(Current-Temperature Calculation)
Electrical computation
Conductor Creep
(IEEE Std)
(Creep-Strain Curves)
Ageing computation
Final System Conditions
Conductor Ampacity
Conductor Tension &
Sag with Creep
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Mechanical Computations
OHL
Data
Weather
VIBRATION LIMIT Conductor
Data
Data
Initial condition:
Load case
EDT at specified
(1 - 6)
Temperature
Maximum conductor
tension (MCT)
Final condition:
specified by load case
Operational
CONDUCTOR
LIMIT
Data
STRUCTURE
LIMIT
Load case
(1 - 6)
Load case
(1 - 6)
Conductor
Insulator
or fitting
At specified Load
Newton-RaphsonChange
iteration of
of State equation
RBS
iteration
using
Change ofAbsolute
State Equation
Conductor
Insulator
Working
Maximum
TensionWorking
 ACWT=
Tension
SF
Newton-Raphson
Conductor RAC
Conductor Tension & Sag
at
T
VLMWT OPERATING & ƒSYSTEM
At TOPERATING (oC)
at the specified load case
Mechanical computation 
IEEE 738 Std
VLMWT ≥ AMWT
EXAMPLE OF LOAD CASE
WIND: 380N/m2
ICE: 9.5mm & 913kg/m3
RBS
SF
ACWT ≥ IMWT
NO
(Current-Temperature
Calculation)
Vibration Limited Maximum
Working
Tension
Electrical computation
 IMWT=
YES
AMWT=ACWT
AMWT=IMWT
AMWT
Conductor Creep

Absolute Maximum Working Tension
(IEEE Std)
(Strain-Strain Curves)
YES
NO
MCT = VLMWT
MCT = AMWT
Conductor Ampacity
Final System Conditions
MCT
Ageing computation
Conductor Tension &
Sag with Creep
At specified Load Case (1-6)
•
•
•
BS EN 50423
BS EN 50341
BS EN 50182
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Electrical Computations
Operational
Data
OHL
Weather Electrical +Conductor
Electrical + physical
physical
Data properties of Data
propertiesData
of
Steel core
Aluminium tube
Aluminium
Steel
0
RDC at 20 C
RDC at 200C
Maximum conductor
tension
Spiralling(MCT)
factor
ASTM method
considers steel
core
Spiralling factor
At specified Load
RDC at TOPoC
RDC at TOPoC
RDC = RST || RAL
Newton-Raphson iteration of
Change of State Equation
RDC = (RST||RAL) at TOPoC
Conductor RAC
Conductor Tension & Skin
Sag factor
at
T
OPERATING & ƒSYSTEM
o
At TOPERATING (oC)
Odd layer conductor
YES
Mechanical computation
IEEE 738 Std
Magnetisation factor
Electrical computation
RAC at TOPoC
(Current-Temperature Calculation)
BS method
Neglects steel core
in the table F.42
of standards
Conductor Creep
NO
Calculation of Ampacity
(IEEE Std 738)
NO
(IEEE Std)
RDC = RAL
(Creep-Strain
(Strain-Strain Curves)
Ageing computation
YES
ICALCULATED≈IESTIMATED
Final System Conditions
RAC + Ampacity at TOPoC
Conductor Ampacity
Conductor Tension &•
Sag with Creep •
BS EN 50182
ASTM B232
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r
Ageing Computations
Operational
OHL
Data
Data
Conductor
Data
Weather
Data
Operational
Data
Conductor
Data
(a)
Creep-Strain curve
Stress
75%
RBS
Maximum conductor
tension (MCT)
Final conductor
modulus of
elasticity
strand settlement &
deformation
At specified Load
D
20%
RBS
Newton-Raphson iteration of
Change of State Equation
Conductor Tension & Sag
At TOPERATING (oC)
Mechanical computation
IEEE 738 Std
10-year creep
line
C
10-year plastic
elongation at 20%RBS
Conductor RAC
at TOPERATING & ƒSYSTEM
IEEE 738 Std
(Current-Temperature Calculation)
(Current-Temperature Calculation)
Electrical computation
Electrical computation
Conductor Creep
(IEEE Std)
(IEEE Std)
(Strain-Strain Curves)
(Creep-Strain Curves)
% elongation
Δ  Δt
Ageing computation
Conductor Ampacity

Conductor Tension &
Sag withFinal
CreepSystem Conditions
C’
(b)
Predictor Equations
IEEE 1283
Conductor Creep
Ageing computation
Conductor Ampacity
C’
A
0
Conductor RAC
at TOPERATING & ƒSYSTEM
Final after high
load creep line
(75%RBS)
Initial creep line
ΔTension
Conductor Tension &
Sag with Creep
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33kV Wood Pole Structure Analysis
1.2m
110m
Minimum
clearance =5.2m
ENA TS 43-40
ENA TS 43-90
BS 3288
BS 1990-1
BS EN 62219
BS EN 50423
0.45m
10.05m
10.05m
SMAX =5.7m
1.8m
0.45m
1.8m
1.2m
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Different Conductor Technologies
AAAC
SOFT ACSR
ACCR (3M)
Aluminium alloy
equivalent properties
to 1350-H19
Pure aluminium
in between
HARD ACSR
ACCC/TW (CTC)
O’ temper
Aluminum
E-glass Fibers
Carbon Fibers
Alumina
Fibers
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AAAC Performance
14PTPPPpppZones
of sag for AAAC
At Max Electrical
+ Mechanical
Loading
4.5
MCT (-5.6˚C)
Tmax (70˚C)
WEAK
CONDUCTOR
ZONE
4.0
3.5
EVERY DAY TENSION
ZONE
WEAK OHL
ZONE
800
700
600
Sag (m)
500
2.5
400
2.0
300
Ampacity (A)
3.0
1.5
Minimum point
200
1.0
0.5
Sag is driven by
conductor self
damping vibration limit
Sag is driven by
conductor strength
0.0
0
5
10
Conductor diameter (mm)
15
Conductor diameter (mm)
100
Sag is driven by OHL
structure strength
0
20
25
30
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Analysis of AAAC
Conductor
Sag
1
Conductor
strength
Conductor
sag
Conductor
Resultant Weight
Minimum
point
1
OHL
strength
Conductor Diameter
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AAAC Performance at different TMAX
14pppt
At different Max Operating
Temperatures
4.0
3.5
90ºC
80ºC
70ºC
60ºC
50ºC
40ºC
Sag (m)
3.0
2.5
2.0
-5.6ºC
1.5
1.0
WEAK CONDUCTOR
ZONE
EVERY DAY TENSION
ZONE
WEAK OHL
ZONE
0.5
0
5
10
15
Conductor Diameter (mm)
20
25
30
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AAAC Performance
SAG plots for Copper, AAAC, and ACSR conductors
1000
90ºC
900
80ºC
800
Ampacity (A)
700
70ºC
600
60ºC
500
400
300
50ºC
200
100
40ºC
0
5
10
15
20
Conductor Diameter (mm)
25
30
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Comparison of AAAC & ACSR
Conductor
Sag
Steel conductor
Aluminium conductor
Increase of
Total
conductor
weight effect
Increase in
strength of
material effect
Minimum
point shift
Conductor Diameter
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Comparison of AAAC & ACSR
SAG plots for Copper, AAAC, and ACSR conductors
4.5
At -5.6oC
AAAC
soft ACSR
hard ACSR
4.0
3.5
Sag (m)
3.0
2.5
2.0
1.5
M
Minimum
point
ini
m
um
po
int
20
Mi
1.0
nim
um
0.5
15
Conductor diameter (mm)
int
10
po
5
25
30
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Comparison of AAAC & ACSR
Creep is included in the calculations
4.5
At -5.6oC
At 70oC
AAAC
soft ACSR
hard ACSR
4.0
3.5
Sag (m)
3.0
2.5
2.0
1.5
1.0
0.5
5
10
15
20
Conductor diameter (mm)
25
30
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Comparison of AAAC & ACSR
pp 14pt
800
0.6
70°C
700
Ampacity at 70°C (A)
600
0.4
500
400
0.3
300
0.2
200
At -5.6oC
At 70oC
0.1
AAAC
soft ACSR
hard ACSR
100
I²R Losses (% of rated power)
0.5
0
0
5
10
15
20
25
30
Conductor diameter (mm)
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Advanced Composite Conductors
SAG plots for Copper, AAAC, and ACSR conductors
Including
10 considered
Year Creep
Creep
is not
4.0
o
At -5.6 C
AAAC
ACCR
ACCC/TW
3.5
o
At 70 C
3M
CTC
Sag (m)
3.0
2.5
2.0
1.5
1.0
0.5
15
20
Conductor diameter (mm)
25
30
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Advanced Composite Conductors
pp 14pt
Ampacity I2R Losses
AAAC
ACCR
ACCC/TW
700
0.6
70°C
3M
CTC
0.5
Ampacity at 70°C (A)
600
0.4
500
400
0.3
300
0.2
200
I²R Losses (% of rated power)
800
0.1
100
0
0
15
20
25
30
Conductor diameter (mm)
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Conclusions
• The methodology can be applied in any
type & size of conductor including system
design limitations & weather.
• AAAC are more suitable than the ACSR for
the 33kV typical wood pole system.
• ACCC/TW develop less sag allowing
uprating of the structure to 66kV.
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What is Next
Performance Analysis of a real system
Any real system?
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