Automation in cable distribution network (10 kV)

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Transcript Automation in cable distribution network (10 kV)

Frankfurt (Germany), 6-9 June 2011
Automation in Distribution Networks (10 kV)
Louise Jakobsen, Danish Energy Association
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Agenda
Background
Definition of automation
Metodes of automation
Prices for automation
Conclusions
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Background
Underground cables have replaced the 10 kV overhead lines in Denmark.
Remote short circuits indicators and remote controlled switchgears are
established in some secondary substations.
In a report we have studied the feasibility to establish automation in
secondary substations.
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Definition of automation
The automation is for fault situations.
The automation locates and isolates short circuit faults,
before the primary station disconnects the faulty feeder.
Normal operation
2
3
1
3
2
Fault situation
Fault
1
2
3
This means use of circuit breakers instead of switchgears!
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Local or central automation
Automation can be established with local or central automation.
Local automation:
 The automation is isolated to selected secondary substations.
 When a fault occurs the automated substations switches.
Control centre
 When an automatic switching has taken place,
the control centre will be notified.
 There is no communication between
the automated secondary substations
- they operate autonomously
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Local or central automation
Central automation:
 The automation has overview of all the secondary substations with
communication.
 The secondary substations report all observations to a control unit
in the control centre (short circuits, earth faults, measurements, etc.).
 The control unit decides how the operational situation has to be
handled based on reports from the automated secondary substations.
Control Centre
Central automation is far more advanced than local automation.
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
No voltage,
no short circuit indicators
Circuit breakers open
Voltage OK, switchgear close
Short circuit indicator sees the fault
Circuit breaker open
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Prices
Additional prices
(2 functional units)
Local automation contra remote switchgear: 900-3000 EUR
Circuit breaker contra Switchgear:
2000 EUR
(both motor operated from factory)
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Reconfiguration based on load or grid losses
Electric cars and heat pumps may introduce new challenges to the
network in terms of overload.
This gives ideas to automated switching based on load or grid losses.
But the investigation shows that:
• it is difficult to find two related
feeders with max. load at
different time
• there are no tests in the standards
showing the electrical durability
at switchgears or circuit breakers
when many switching are carried out
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Grid losses
Calculation of grid losses at ideal meshed 10 kV grid and grid with
feeders shows that the biggest losses are in the transformers.
Switching
Normal (feeder)
Meshed
Daily
Losses in MWh
Cables Transformers Total
39,3
203
242
35,3
203
238
37,6
203
240h
The annual saving at daily switching after losses is 1,7 MWh.
The conclusion is that the cost for automation to control the load and
losses will be much higher than the benefits.
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Conclusion
Automation in secondary substations is suited for:
• Feeders with branches
• Grids with many consumers
• Long feeders which in the case of a fault can be split up, so that half
of the feeder can be reconnected quickly or get back-up supply.
Benchmarking
SAIDI
The quality of supply is high in Denmark (SAIFI 0,46)
so the conclusion is:
 that the cost for automation is too high!
(but for network operators who are
near or over the threshold value
in benchmarking automation
might pay off).
(SAIFI
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Conclusion
Automation is a new technical possibility.
Society often embraces technology and expects that businesses and
government use the technology.
In time automation might be demanded by society:
 in many secondary substations to improve quality of supply
 at consumers with important functions like hospitals, police stations
 at consumers with a great number of people gathering like stadiums,
shopping centres and similar places
 as a service to companies where long-term outages are expensive.
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811
Frankfurt (Germany), 6-9 June 2011
Thank you for your attention
Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811