Hotspot analyses for
Dynamic Power Line Rating
Dirk Malda
Willy Zittersteijn, Melanie Hoffmann, Jelle Wisse
EWEA workshop Leuven, October 2nd 2015
• Technical explanation of MeteoGroup’s Dynamic
Line Rating (DLR) model
• Probability forecasts for reducing risks
• Hotspot analysis to refine DLR
• Hotspot observations used for improved forecast
• Future Outlook
Outline
Transport capacity model
• 𝑰 transport capacity
• 𝑹 line resistance
line properties
• 𝑺𝒊𝒏 solar radiation
geographical location, date and
time
orientation of line
• 𝑳𝒐𝒖𝒕 outgoing longw radiation
Tline
• 𝑳𝒊𝒏 incoming longw radiation
TT, N
• 𝑯 sensible heat flux
TT, Tline, FF
4
Sin
>> Lout
Lin >
H
𝐼2𝑅 = 𝐻 − 𝑆𝑖𝑛 + 𝐿𝑜𝑢𝑡 − 𝐿𝑖𝑛
𝐼 =𝐻 − 𝑆𝑖𝑛 + 𝐿𝑜𝑢𝑡 − 𝐿𝑖𝑛
𝑅
Shortwave radiation on line
5
E
S
W
N
E
S
W
N
Capacity is strongly related to wind speed
0.6 m/s
0 oC
35 oC
The lowest capacity determines the line capacity!
Dynamic line rate model
Dynamic line rate model
Cigré
Land use (roughness length)
Weather forecast
Transport capacity forecast
Probability forecast
2
4
6
8
10
12
14
16
18
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
4
5
6
7
8
9
10
11
12
13
14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Temperature
Wind speed
Transport capacity
4
6
8
10
12
14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
80% Chance of exceeding
Most likely value
20% Chance of exceeding
Cigré
Monte Carlo
Dynamic line rate model in forecast modeTransport capacityTransport capacity and wind speed (m/s) 2010-06-08 21:00
Validation of reliability forecast for Dynamic Line Rating
Risk!
Safe, conservative
approach
Perfect forecast, but close to risk areaMeteoGroup Model:
efficiency approach
Example of
perfect forecast:
80% of measured
line capacity is
above 80%
confidence level
forecast
Steps to become more accurate
1. Determine critical line sections (hotspots)
2. Installing real time (weather) monitoring on critical sections
3. Use weather data to calibrate the model forecast
Improving the accuracy by determination of
hotspots
Defining hotspots: Selection of surrounding weather stations
Defining hotspots: Using 10 years of historical observations of surrounding weather
stations
• Weather observation data are
downscaled towards the power
lines
• Downscaling method takes into
account:
a) local information along the lines
b) local situation of weather stations
c) actual weather
Defining hotspots – low wind speeds
N
E
S
W
NWNE
SESW
• Roughness method:
High roughness means
low wind speed Low
roughness
High
roughness
Location of pylon
Current fixed capacity based on line
properties
Higher max
Ampacity
Lower max
Ampacity
Higher max
Ampacity
Lower max
Ampacity
Higher max
Ampacity
• Line capacities are
not always
homogeneous!
Average windspeed June July and August
2.0 3.4 m/s
Average daily maximum temperature June July
and August20.0 24.0°C
Average relative capacity
1.40 1.50
Limited section count
20
Number of hours in June, July and August a section is the limited
section
Detailed focus
Followed by visit
Final hotspots
23
Weather stationSolar panel
Height: 10 m above
ground level
Installation of weather station
Use observations to improve dynamic
line rating forecastMOS
equations
MOS
forecast
Downscaled
forecast
Meteobase
forecast
Historical
OBS
Historical
MODEL
Topographical
information
Edit
meteorologist
+
MOS
equations
Actual
MODEL
Actual
OBS+ +
MOS
forecast +
Downscaled
forecast +
Dynamic line rating model
In July is 60% of the time more than 150% relative capacity available
>150% capacity
Example: Capacity throughout the year related to
hotspot analyses
>125% capacity
Future outlook