Frankfurt (Germany), 6-9 June 2011

John MILLAR – Finland – RT.1a/5a

Distribution Network Planning and Underground Cables

Keeping overview while attending to detail

…with much appreciated help from, among others: Prof. Matti Lehtonen and Eero Saarijärvi

Frankfurt (Germany), 6-9 June 2011

My research fields

Ampacity of underground cables Practical investigations of their thermal

environment Development of real-time algorithms

Network planning algorithm MV, LV and MV-LV…

Frankfurt (Germany), 6-9 June 2011

Underground cable rating

Suggest steady-state for planning The future is hard to predict…

Cyclic rating for existing, but note: Needs thorough knowledge of installed conditions Must consider:

Moisture migration External heat sources Condition of existing cables

Frankfurt (Germany), 6-9 June 2011

Cyclic vs. Steady-state rating forexisting MV cables

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65 °C steady-state current limit

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90 °C steady-state current limit

65 °C:• steady-state rating: 340A• cyclic rating: 385 A

90 °C:• steady-state rating: 382 A• cyclic rating: 462 A

Frankfurt (Germany), 6-9 June 2011

Cables: Installation challenges Crowding of underground services

Duct bank and tube installation ratings more challenging

Charging current >> load currents for long rural cable connections

Frankfurt (Germany), 6-9 June 2011

Distribution network planning Automating the laborious task of trial and

error planning An algorithm that deals with real networks

and realistic planning issues in reasonable computation times

Trying to keep up with contemporary developments...

Frankfurt (Germany), 6-9 June 2011

VOH_MV ‘Optimally’ routes lines between fixed

primary and secondary substations, i.e. plans the MV network.• Optimal or full switching – 3 levels• Optimal or full backup connections

between main feeders• Existing network consideration and

upgrade times• User-preferred network

Frankfurt (Germany), 6-9 June 2011

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VOH_MV, e.g.:

Frankfurt (Germany), 6-9 June 2011

VOH_MV_LV Starts with LV customers and primary

substation positions ‘Optimises’, according to various planning

philosophies: secondary substations (no. and positions) connection (cable) boxes (no. and positions) And, of course the MV and LV network

routing – switches – backup

Frankfurt (Germany), 6-9 June 2011

VOH_MV_LVOne approach

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PrimarySubstations

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Frankfurt (Germany), 6-9 June 2011

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VOH_MV_LVAnother approach

Frankfurt (Germany), 6-9 June 2011

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VOH_MV_LVand another approach

Frankfurt (Germany), 6-9 June 2011

VOH_MV_LVand finally...

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Frankfurt (Germany), 6-9 June 2011

Contemporary developments mmm... We know that this algorithm

should be able to handle distributed generation – coming ‘soon’! What else?

Many thanks!