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Transmission Policy InstituteSheraton Downtown — Denver, Colorado

April 20-21, 2011

New Transmission Options – Case StudySuperconductor Cables

What is a Superconductor?

• Superconductors 100/25

• Superconductors are materials that exhibit unique electrical characteristics:

- Little to no resistance to the flow ofelectricity

- Ability to carry hundreds of times as muchelectrical current as copper

- Repel magnetic fields

• These characteristics require:

- Cooling below a critical temperature

- Current levels below a critical current

• Above these critical levels the material “quenches”, and current must flow elsewhere

• New, ceramic high temperature superconductor (HTS) material discovered in 1986

- Requires less cooling; cost effective liquid nitrogen may be used

Development of HTS has enabled utility commercial applications

Current

Capacity

Equivalents

Superconductor Cable’s ELECTRICAL Characteristics

• Very high power transfer capability compared to

conventional cables solves many siting problems

• Very low impedance reduces loading on parallel lines

and equipment

• Minimal magnetic field and elimination of heat

simplifies placement concerns, minimizes right-of-way,

and is easy on the environment

• Optional HTS cables with fault current management

capabilities eliminate need to upgrade existing equipment

HTS Cables offer unique capabilities

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Superconductor Cables Driving to Commercial Adoption

Dozens of successful HTS cable projects globally in service or in process

2001 2002199919981997 2010 2011 201320122000 2009200820072006200520042003

US/DTE – 24kV (120m)

US/EPRI – 115kV (50m)

DENMARK – 36kV (30m)

CHINA – 35kV (30m)

JAPAN – 66kV (30M)

US/Southwire – 12.5kV (30m)

KOREA – 22.9kV (30m)

US/Nat. Grid – 34.5kV (400m)

JAPAN – 77kV (500m)

SPAIN – 10kV (30m)

US/AEP – 13.8 kV (200m)

CHINA – 10.5kV (75m)

US/LIPA Phase I – 138kV (600m)

KOREA – 22.9kV (100m)

MEXICO – 15kV (30m)

CHINA – 110 kV (30m)

KOREA –22.9kV (100m)

RUSSIA – 35 kV (30m)

Powered by AMSC wire

Powered by other wire

JAPAN – 66kV (250m)

SHANGHAI PROJECT (SECRI)

US/ConEd – 13.8 kV (220m)

US/LIPA Phase II – 138 kV (600m)

KOREA/KEPCO – 22.9kV (500m)

SPAIN – 20kV (30m)

KOREA/KEPCO – 154kV (100m)

Project list updated 4-2010

US/TresAmigas-200kVdc(10km)

Undecided

China/SGCC– 110kV (1km)

Korea/KEPCO – 154kV (1km)

Korea – 22.9kV (3km)

Key HTS Cable PHYSICAL Characteristics

Familiar Physical Characteristics

• Looks like conventional cable

• May be spliced

• May be placed in ducts or direct buried

• Must be cooled with liquid nitrogen

• No thermal constraints for placement

HTS Cables offer unique capabilities in a familiar package

Unique Electrical Characteristics

• Very high power transfer capability

• Very low impedance

• Minimal magnetic field

• Elimination of heat

• HTS cables with fault current management

Power Transfer Equivalency of Superconductor Cables

Superconductor cables provide transmission-level power transfer at medium voltage

* No XLPE cable de-rating factors applied. Superconductor rating based on conventional 4000A breaker rating

0 200 400 600 800 1000

13.8kV

34.5kV

69kV

138kV

230kV

345kV

Power Transfer Capability - 3-phase MVA

XLPE

XLPE

XLPE

XLPE

XLPE

XLPE

HTS

HTS

HTS

HTS

• Same Voltage, More Power

- Greatly increased power transfer capacity at any voltage level

• Same Power, Lower Voltage

- New MV versus HV Siting Opportunity

• “MV Transmission”

• Ideal for NIMBY & ROW sparse environments

Simplifying Transmission Siting

HTS Cables Offer New Options to Siting Power Lines

Photo courtesy Consolidated Edison

One MV HTS Cable can replace:

• Many conventional underground

circuits

• Overhead transmission line

Background

Holbrook Superconductor

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LIPA is a NYS Authority established in 1998 as the primary electric service provider for LI1207 sq. mi. (roughly 100 miles by 12 miles)

Nassau, Suffolk and the Rockaway Peninsula

Population of about 3 million1.1 million residential customers

100,000 commercial customers

Since 1998, 5.7% population growth (172,000 more people)

$2.0 billion invested in system upgrades and improvements

LIPA owns the assets All T&D operations and most IS systems are outsourced

LIPA

LIPA Transmission System

LIPA Long Term Needs

Must meet increasing power demands in existing ROWs

Load continues to increase

LIPA expects 1200 MW of new load by 2020 - Major transmission reinforcements

will be required

Project Provides Potential Tool to Meet LIPA’s Long Term Needs

ROW Congestion - HTS Cables provide increased power transfer capability

within existing ROWs (2 - 5 times the capacity in the same space)

Overhead Permitting Problems

Potential cost savings compared to upgrading to 345 kV transmission

system

Site Specific

East / West transfer capability increase required by upcoming power

insertions

Why was LIPA Interested in a

Superconductor Cable?

Land and Route

Holbrook Substation

Port

Jefferson Shoreham

Wading

River

Miller

Place

Terryville

CentereachSuperconductor

Superconductor Example: 138 kV, 575MW Capacity

4 ft ROW

200 ft ROW

• Self contained thermal envelope No thermal de-rating

• Minimal magnetic field No parallel line de-

rating• Lower Impedance

Longer practical distance

Superconductor Cables Simplify Placement and Offer New Options to Siting Lines

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Long Island Power Authority Cable System

• Energized in April 2008

• World’s first HTS transmission voltage cable system in the grid

• Longest, most powerful superconductor cable in the world

• Able to carry 574 MW of power in a four-foot-wide right of way

• Landmark cable installation proving high power, transmission level applications

Over 15 years of HTS Cable Experience

Next Step??

Holbrook Superconductor

Proposed Future Project

Required to Support East/West Power Flows

Extend 138kV superconductor cable to meet future transmission

requirements

Located between Holbrook and Central Islip substations (6.2 miles)

Originally planned for summer 2012 – delayed

due to lower load growth

ALL underground; eliminates need for

conventional overhead-underground hybrid

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Present Status and Future Direction of HTS Power Application in KEPCO

Y o u n g - J i n W O N

P o w e r G r i d P l a n n i n g T e a m , K E P C O

Large Capacity & Low loss + Eco-friendly

HTS Cable & SFCL

High cost for Civil works

Difficulty of excavating roads for const’n conduit or culvert

NIMBY for the construction of new substations

To cope with continuous increasing of fault current

Countermeasures to renew the aged power cables

Ⅱ. Why ? HTS System in KEPCO ?

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Supplying the huge buildings with electric power by HTS cables

Replacing 22.9kV conventional cables(2~3lines) with the superconducting

cables using the existing conduit or culverts without additional civil works

22.9 kVSW/S

22.9 kV Superconducting Cablesto replace 154 kV conventional cables

~

154 kV S/S in the suburbs

SFCL

SFCL

SFCL

22.9 kVSW/S

22.9 kV Superconducting Cablesto replace 22.9kV conventional cables

Superconducting Transformers

22.9 kVSW/S

Downtown Area

Circuit Breaker(Normal open)

Superconducting Power System (SPS) applying distributed switching stations

for metropolitan areas

Apply superconducting power devices (cables, transformers, FCLs) to real power system

154kV transmission power system 22.9kV superconducting power system

Replace 154kV substations in downtown with 22.9kV underground switching stations

Replace 154kV conventional cables with 22.9kV superconducting cables

Bulk power transfer by superconducting cables and transformers & Fault current reduction by SFCL

Skip substations

Reduce construction costs

Environment-friendly

Avoid civil petitions

154kV

S/S

154kVS/S

154kVS/S

154kV

S/S

Downtown

154kV conventional cables

154kV

S/S

154kV

S/S

22.9kVSW/S

22.9kVSW/S

22.9kVSW/S

22.9kVSW/S

22.9kVSW/S

22.9kVSW/S

22.9 kVSuperconducting cables

Downtown

154kV conventional cables

SuburbSuburb

One of solutions for the site problem

No substations & Compact size Easy to find a site for power facilities in downtown

Underground switching stations Make a park on the switching stations

Economic benefits

Reduction of cost for buying land

The site for 22.9kV switching stations is less than 30%, compared to 154kV substations.

No additional construction cost

We can use established underground facilities such as existing electric power conduit pipes.

Environmental and social benefits

Environment-friendly Avoid the trend of NIMBY

No oil for cooling the system

Free of the explosion danger (Superconducting transformer)

No additional construction Reduce the construction cost and ease traffic congestion

High efficiency and loss of superconductor Save energy and reduce CO2 emission

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DC Superconductor cables for long distance

transmission

Superconductor Advantages with DC Power

• When carrying DC current, superconductors themselves

are perfectly lossless

- Regardless of length

- Regardless of power rating

• Benefits

- No power limitations based on current-based losses

- Allows lower voltage, higher current transmission

- Allows underground construction

Superconductors open the door for a true underground transmission system

Superconductor PowerPipes™

Superconductor PowerPipes combine:

• Superconductor cables

• DC power transmission

The result:

• A high capacity electric transmission “pipeline”

that is:

Underground and easy to site

Highly efficient

Offers greater security than other technologies

Provides for multiple power on- and off-ramps

The challenge of moving renewable power long distances needs another option

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Today’s Key Energy Challenge: Carrying 100’s of Gigawatts of Green Power to Market

Many Issues

• Multiple Sources

• Multiple Destinations

• Cost Allocation

• Siting

• Transmission Across

Interconnections

• Losses

AC Overhead Transmission

• Higher power and longer distances require higher

voltages

• Losses

• Limited power flow

control

• Power transmission

characteristics

• Public opposition

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0.0

1.0

2.0

3.0

4.0

5.0

0 200 400 600 800 1000

Po

wer

Tra

nsfe

r C

ap

ab

ilit

y,

GW

Line Length in Miles

Transfer Capability Versus Distance of a 765 kV Overhead Line

0%

2%

4%

6%

8%

10%

12%

14%

16%

100 200 300 400 500 600 700 800 900 1000

% L

os

se

s (E

st.

)

Miles

5GW of Renewable Energy Transmission

Range of Losses for Various 765kV Overhead Line Designs

Courtesy Argonne National Lab

Dominant form of transmission, but

many challenges

Existing Transmission Options

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AC

Point-to-

Point

HVDC

Multi-

terminal

VSC

HVDC AC

Point-to-

Point

HVDC

Multi-

terminal

VSC

HVDC

Multi-Terminal

Superconductor

Pipeline

Low Power (<1GW) Short (<100 mile) lines

Low Power (<1GW) Moderate (100-400 mile) lines

Low Power (<1GW) Long (>400 mile) lines

Moderate Power (1-5GW) Short (<100 mile) lines

Moderate Power (1-5GW) Moderate (100-400 mile) lines

Moderate Power (1-5GW) Long (>400 mile) lines

High Power (>5GW) Short (<100 mile) lines

High Power (>5GW) Moderate (100-400 mile) lines

High Power (>5GW) Long (>400 mile) lines

SUITABLE TRANSMISSION SOLUTIONS

Overhead Solutions Underground Solutions

TRANSMISSION LINE POWER AND DISTANCE

REQUIREMENTS

No suitable solution for high power, long distance, underground transmission

HVDC Superconductor Cables

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AC

Point-to-

Point

HVDC

Multi-

terminal

VSC

HVDC AC

Point-to-

Point

HVDC

Multi-

terminal

VSC

HVDC

Multi-Terminal

Superconductor

Pipeline

Low Power (<1GW) Short (<100 mile) lines

Low Power (<1GW) Moderate (100-400 mile) lines

Low Power (<1GW) Long (>400 mile) lines

Moderate Power (1-5GW) Short (<100 mile) lines

Moderate Power (1-5GW) Moderate (100-400 mile) lines

Moderate Power (1-5GW) Long (>400 mile) lines

High Power (>5GW) Short (<100 mile) lines

High Power (>5GW) Moderate (100-400 mile) lines

High Power (>5GW) Long (>400 mile) lines

TRANSMISSION LINE POWER AND DISTANCE

REQUIREMENTS

SUITABLE TRANSMISSION SOLUTIONS

Overhead Solutions Underground Solutions

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Fit of DC superconductor cables for underground, long distance, high power, multi-terminal transmission

Operational Opportunities for DC Superconductor Cables: ELECTRICAL EFFICIENCY

• Converter losses 2%, cooling losses 22kW/km

• Overall losses 2.75% for 5GW @1600km (2.4% for 10GW)

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0%

2%

4%

6%

8%

10%

12%

14%

0 100 200 300 400 500 600 700 800 900 1000

Lo

ss

es

(%

of

5G

W)

Length (miles)

Losses for 5GW Transmission

765kV OH, 2 Lines

765kV OH, 3 Lines

+/-300kV Underground DC [6]

Overhead +/-800kV DC [7]

+/-200kV Superconductor Pipeline

Optimized 765kV, 3 Lines [8]

Loss advantage increases with distance and MW rating

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Rights of Way Already Exist for Superconductor Electricity Pipelines

Cost Analysis

• 5GW, 1000 mile Superconductor DC Cable

System

- US$8.8 Million/mile two pole cable

- Costs include DC terminals, refrigeration, installation

- Doubling capacity to 10GW increases cable cost by

only 50% (extra converters not included)

• Cost Competitive with EHV AC

- US$2.5 - $5.5 Million/mile

- 2 to 3 lines needed for same capacity

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Long distance, high power superconductor DC cables

are cost competitive with EHV AC lines

Advantages of DC Superconductor Cables

• Highest power capacity

• Highest efficiency (lowest power losses) of any transmission technology

• Ideal for very long distances

• Capable of transferring power across the three U.S. interconnections

• Able to accept power from multiple distributed sources, and precisely deliver power to multiple distributed destinations

• Underground construction with minimum right of way requirement

• Simplified cost allocation due to precise controllability of DC terminals

• Minimizes interaction with existing AC grid, reducing costs and increasing operational flexibility

• Cost competitive

DC Superconductor PowerPipes are uniquely and ideally suited to move renewable energy to distant load centers

Tres Amigas SuperStation Project

Western

Interconnection

Eastern

Interconnection

Texas

Interconnection

Unique 3-way DC project to link the three U.S. Interconnections

Tres Amigas Project to Use Superconductor Electricity Pipeline

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Summary

AC and DC superconductor cables offer

new option for high power, underground,

transmission of electric power

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Transmission Grid of the Future