Scottish Hydro Electric Transmission Limited (SHETL)

energymadebetter

Presentation to the Argyll and Bute

Renewable Energy Alliance (ABRA)

“A Wires Overview”Wednesday 22nd June 2011

Alec Morrison – Transmission Commercial Policy Manager

Transmission and Distribution

Transmission system - the ‘motorways’

Distribution systems – the ‘A’ and ‘B’ roads

The grid functions as a single ‘meshed’ network

PORT ANN BSP

InverarayClachan

Nant

TAYNUILT BSPCruachan

Dalmally

Sloy

Windyhill SP

Argyll & Kintyre

DUNOON BSP

CARRADALE BSP

Hunterston

Inverarnan

132 kV275 kV

ARRAN

MULL

BUTE

COWALJURA

ColonsayJura

SouthKintyre

Cowal

Arran

Islay DunoonGrid

CarradaleGrid

Port AnnGrid

Tiree

Mull

Ardnamurchan(mainland)

Coll

Inveraray

Fort WilliamGrid

TaynuiltGrid

Connection Summary – 12.7GW (Excludes Pre-1990 Hydro)

Connected, 1.1

Contracted O nshore, 4.8

Contracted O ffshore, 4.6

Future O ffshore & Marine, 2.2

0

2

4

6

8

10

12

14

GW

Existing system can accommodate 1.5GW.

Transmission works have been identified to accommodate additional contracted schemes. A number are under construction.

Future position kept under review. Additional transmission works may be required, but will depend on utilisation of existing works.

South West Generation Statistics

• Connected– Small DG: 56MW– Large: 161MW

• Contracted– Small DG: 63MW – Large Onshore: 256MW– Large Offshore: 400MW

• Future– Onshore:

Transmission Development Proposals (1)

Balance between “make best use of what we’ve got” and “creating additional transmission capacity”

• Completed– Greater Grid Supply Point capacity at Taynuilt, Port Ann and Carradale– 3rd 132kV Circuit between Sloy and Inveraray– Inverarnan 275 / 132kV substation

• Short-Term Proposals– Connect & Manage

• Medium-Term Reinforcements– Hunterston – Crossaig– Crossaig - Carradale

Transmission Development Proposals (2)

Balance between “make best use of what we’ve got” and “creating additional transmission capacity”

• Longer-Term Reinforcements– 132kV Rebuild between Inveraray and Crossaig, forecast October 2017– 132kV Rebuild between Inveraray and Taynuilt, forecast October 2015

– HVDC link across South Kintyre (via underground cable) to Hunterston - WITHDRAWN

– Potential for HVDC Converter Station on Islay and an HVDC link to the Ayrshire coast

PORT ANN BSP

InverarayClachan

Nant

TAYNUILT BSPCruachan

Dalmally

Sloy

Windyhill SP

Argyll & Kintyre

DUNOON BSP

CARRADALE BSP

Hunterston

Inverarnan

132 kV275 kV

ARRAN

MULL

BUTE

COWALJURA

Hunterston – Crossaig Update

• Delayed from 2013 to 2015

– Route constraints (limited seabed routes for subsea crossing to the north of Arran); unable to lay 2 circuits (3 x 1c 132kV cables per circuit, a total of 6 cables); alternative is 3 circuits (1 x 3c 132kV cable per circuit, a total of 3 cables). This has required additional seabed survey.

– Alternative is too heavy for traditional subsea laying techniques given the water depth of up to 170m.

– Considering alternative 220kV technology, 2 circuits (1 x 3c 220kV cable per circuit, 2 cables), but requires additional development, testing and quality assurance for asset integrity and life.

– Availability of cable manufacturing and installation capacity is constrained due to high demand from offshore wind installations.

Example 132kV Substation with woodpole ‘Trident’ overhead line Example 132kV Substation

Typical AC 132kV Wood Pole Overhead Lines

13

HVDC Infrastructure

• Converter station

• Onshore HVDC cable(s)

• Switching station

• Offshore HVDC cable(s)

• Offshore HVDC connection hub

HVDC Converter Stations

• Large buildings with outside sub station infrastructure

• Likely dimensions for shed 120 m x 60 m x 15 m

• Overall footprint 400 m by 400 m

ABB technology

Siemens technology

Estlink converter station shedsEstlink converter station site

Transportation

• Converter and substation will require delivery of heavy loads

• A few may exceed 200 tonnes

• Special vehicles will spread load across many axles

• Sharp turns and hump-backs may create issues

• Potential to use local harbours as delivery points

Typical vehicle for transformer transport

Thank you for listening

Do you have any Questions?

Alec MorrisonSHETL, Transmission Commercial Policy Manager

Tel: 01738 456770 email: alec.morrison@sse.com

Slide Number 1Transmission and DistributionSlide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Example 132kV Substation with woodpole ‘Trident’ overhead lineSlide Number 13Slide Number 14Slide Number 15Slide Number 16