Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811

Frankfurt (Germany), 6-9 June 2011

Louise Jakobsen, Danish Energy Association

Automation in Distribution Networks (10 kV)

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 automationThe automation is for fault situations.

The automation locates and isolates short circuit faults,

before the primary station disconnects the faulty feeder.

This means use of circuit breakers instead of switchgears!

2 3

1

2 3

1

2 3

Normal operation

Fault situation

Fault

Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811

Frankfurt (Germany), 6-9 June 2011

Local or central automationAutomation 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. 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

Control centre

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.

Central automation is far more advanced than local automation.

Control Centre

Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811

Frankfurt (Germany), 6-9 June 2011

Short circuit indicator sees the fault

Circuit breaker open

No voltage,

no short circuit indicators

Circuit breakers open Voltage OK, switchgear close

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 lossesElectric cars and heat pumps may introduce new challenges to thenetwork 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 standardsshowing the electrical durabilityat switchgears or circuit breakerswhen 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.

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.

Losses in MWh Switching

Cables Transformers Total

Normal (feeder) 39,3 203 242

Meshed 35,3 203 238

Daily 37,6 203 240h

Louise Jakobsen, Danish Energy Association – Denmark – Session 3 – Paper 0811

Frankfurt (Germany), 6-9 June 2011

ConclusionAutomation 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.

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 arenear or over the threshold valuein benchmarking automationmight pay off).

Benchmarking

(SAIFI

SA

IDI

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