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Automatic regulation and disconnection of wind power in the 50 kV system on Öland based on dynamic line rating Anna Pettersson E.ON Elnät Sverige AB 2014-09-30
Automatic regulation and disconnection of wind power in the 50 kV system on Öland based on dynamic line rating Anna Pettersson E.ON Elnät Sverige AB 2014-09-30
Automatic regulation and disconnection of wind power
Regulation of active power can be needed when the grid is not fully dimensioned for the total connected production.
Depending on the time requirements, the regulation can be manual or automatic.
Depending on the consequence of a non functional regulation, a decision has to be made if there will be any backup control actions.
Depending on the need of regulation, the control can be either dynamic or static.
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Basic principles Dynamic Line Rating (DLR) – overhead lines
Overhead lines must have minimum distance to the ground. Regulated in ELSÄK-FS in Sweden.
Normally are all overhead lines dimensioned for 50°C, conductor temperature.
At 50°C, the tolerated power rating of a particular type of line is given due to the specific weather conditions. The colder or windier it gets, more power can be transmitted without exceeding line temperatures of 50°C.
We use three different weather scenarios in static rating. Summer, autumn/spring and winter.
When measuring the line temperature or the sag of the line, a more exact estimation of the actual line rating can be made.
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50 kV system on Öland based on dynamic line rating
Short background of the project: Additional 50 MW wind power connected in the 50 kV system on Öland (Kårehamn).
Significant amount of wind power already connected
Öland today: 170 MW wind power (north 125 MW, south 45 MW) Maximal load: approximately 74 MW (north 34 MW, south 40 MW) Minimal load: approximately 22MW (north 11MW, south 11MW) When Kårehamn produce more than 30 MW, there is a fear that
some of the 50 kV overhead lines will be overloaded.
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Overview 50 kV system on north part of Öland
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Överföringskapacitet (MVA)
Driftfall Normal (ledartemp. 50°C)
Reserv (ledartemp. 70°C)
Typ sommar/höst/vinter sommar/höst/vinter 25°C/10°C/0°C 25°C/10°C/0°C
157 Al59 29/40/47 47/56/62
Grid protection – 50 kV system on north part of Öland
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Weather station
IED – P341 Alstom
Direct temperature meter – Power Donut USi
50 MW Kårehamn
Grid protection’s display
50 kV system on north part of Öland 28/10-2013
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Överföringskapacitet (MVA)
Driftfall Normal (ledartemp. 50°C)
Reserv (ledartemp. 70°C)
Typ sommar/höst/vinter sommar/höst/vinter 25°C/10°C/0°C 25°C/10°C/0°C 157 Al59 29/40/47 47/56/62
50 kV system on north part of Öland 28/10-2013
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Överföringskapacitet (A)
Driftfall Normal (ledartemp. 50°C)
Reserv (ledartemp. 70°C)
Typ sommar/höst/vinter sommar/höst/vinter 25°C/10°C/0°C 25°C/10°C/0°C 157 Al59 316/438/518 522/616/682
The difference between calculated capacity and actual current in Linsänkan (28/3-18/8 2014)
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Experiences so far
There has been no regulation of the production in Kårehamn due to overload, yet (1 year in use).
We have had some technical problems with the Power Donuts.
We are planning to use automatic regulation of wind power in other projects (both dynamic and/or static).
E.ON Elnät has a new technical guideline for automatic regulation / Grid Protection.
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