Yokohama Project

- Demonstration of High Temperature

Superconducting Cable -

March 2015

MAYEKAWA MFG. CO., LTD.

1. Project overview and High Temperature superconducting (HTS) cable system.

2. High performance refrigerator for HTS cable.

3. DC HTS Power Transmission Line.

O U T L I N E

1. Project overview and HTS cable system

Advantages of HTS cable system

600800

2100

340

Conventional

Cable

Troughing

Tunnel

[size: mm]

150

230

Superconducting cable

150

Conduit

Conventional cable

275 kV, 700 MVA/3cc

HTS cable

66 kV, 700 MVA/3cc

HTS cable will be applied to power plant in service, conduit of

urban area and long distance & high power transmission.

Large capacity : equivalent to conventional cable with lower voltage.

HTS cable is able to reduce number of sub-station.

Compact size : installed within small conduit in urban area.

HTS cable can be reduced the tunnel construction cost.

Low loss : less than 1/2 compared with conventional cable.

Impossible structure of electricity stealing.

Right on way : protect natural scenery. Not influenced magnetic field.

Project overview

Project members

Project outlines

Asahi S/S, Yokohama, TEPCO’s power system

AC 66 kV - 2 kA - 200 MVA class HTS cable with 1G DI-BSCCO wire

Compact 3-in-One cable design for 150 mm conduit

Approx. 250 meter cable with a joint and terminations

TEPCO

SEI

MAYEKAWA

Host power company

HTS cable system design,

manufacture and installation

Cooling system design, manufacture and

Installation. Refrigerator development

Supported by NEDO & MTEI

Tokyo

Site

Project schedule

Starting the project : FY2007~

Demonstration test in real grid has started on October 29, 2012 and finished on

December 25, 2013.

Development of high performance refrigerator was started in 2011.

Field test with new refrigerator will be implemented from 2015.

FY 2010

(Asahi S/S)

FY 2013FY 2009FY 2008FY 2007

Field test

FY 2012FY 2011

Manufacture and

Pre-Operation test

-Cooling system

(MAYEKAWA)

High

performance

refrigerator

development

Design

- Cable, Joint,

Termination and

Cooling system

Installation

@Asahi

Unit test

@AsahiC

on

ne

ctin

g te

st

Re

al g

rid o

pe

ratio

n

Design and

preliminary test

Turbo-comp.

and expander

Performance

test

Design and

manufactureCold Box and

Comp. unit

LN2 system

manufacture

Performance test

-Cable, Joint,

Termination

Cable

manufacture

Move

FY 2014 FY 2015

Re

al g

rid o

pe

ratio

n

Move to

Asahi S/S

Conventional

refrigerator

High

performance

refrigerator

154kV bus line

【Additional equipment】

HTS cable

~240 meter

LS1

LST10

CB

LS

LS

66kV bus line

CB

LS

LS

Transformer

154/66kV

3φ200MVA CB1

CB2

LS2

HTS cable is connected

low voltage of 66 kV bus line

CB：Circuit Breaker

LS：Line Switch

Circuit diagram

Line switch (SCT10)

Is installed in by-pass

circuit for emergency

Trans

154/66kV

200MVA

Monitoring

house

Joint

CB

CH

LS1

CB1

CH

LS10

CB2

T2 T1

P

Ref

Site o

ffice

LS2

~250 meter HTS cable

Terminations

Cooling system

house

Trans

154/66kV

200MVA

Monitoring

house

Joint

CB

CH

LS1

CB1

CH

LS10

CB2

T2 T1

P

Ref

Site o

ffice

LS2

~250 meter HTS cable

Terminations

Cooling system

house

Layout of test center in Asahi S/S

Terminations

HTS cable

Cable joint

Cooling system house

66 kV XLPE cable

66 kV bus line

Copper Stranded Former

Electrical Insulation

（PPLP＋LN2）LN2 Flow Channel

Superconducting Shield

（BSCCO tapesin2 layers)

Superconducting Conductor

（BSCCO tapesin4 layers)

Stainless Steel Double

Corrugated Cryostat

Copper Shield

3-in-One cable design achieve compact size.

HTS cable structure

Vacuum Insulation

LN2: Liquid Nitrogen

Characteristics for HTS Cable System

Cable Low heat loss AC loss of 1 W/m/ph @ 2 kA

Heat loss of 3 W/m

Withstand against fault

current

Capable of bearing Short circuit current

with 31.5kA, 2sec @ 66 kV

Cooling

system

w/o LN2 consumption

w/o vaporization

for high voltage dielectric

properties

Keep LN2 in Sub-cooled state

• Temperature : 67 to 77 K

• Pressure : 0.2 to 0.5 MPaG

• Circulate flow rate : 40 L/min

Maintenance without

shutdown

Apparatus redundancy & automatic

switching at their failure

Operation Automatic control on LN2

state without operator

Establish remote observation / alarm

system

Cooling system(1st Generation)

Refrigerators

Reservoir

Pumps

Apparatus Spec Unit(s)Redun-

dancy

Refrigerator

(Stirling type)1 kW @ 77 K 6 1 unit

Pump

(centrifugal type)40 L/min 2 1 unit

Reservoir 1000 L 1 -

ReservoirPump

CableRef.：Refrigerator

LN2

Cable

Heater

Flow meter

Ref.

Ref.

Ref.

Ref.

Ref.

Ref.

F

M

M

Motor

Valve

65

69

73

77

81

Tem

pera

ture

［K］

0

0.4

0.8

1.2

1.6

30

35

40

45

50

10/28 12/27 2/25 4/26 6/25 8/24 10/23 12/22

Pre

ssure［M

PaG

］

Ele

ctr

ic c

urr

ent［ｋA

ms］

Flo

w rate［L

/min］

DATE

Results of operational state

System was stable in the state of constant

and change of the operation temperature

LN2 conditions remained

steady for one year

Items Results of demonstration test

Periodical inspection 10 Jun 2013 ~ 21 Jun 2013, 22 July 2013 ~ 22 July 2013

Maximum electric current 1127 A (August 10 2013)

Voltage 63.9 kV ~ 67.1 kV

LN2 temperature

LN2 Pressure

Flow rateElectric Current

2. High performance refrigerator for HTS

cable

Technical Issues

Technical issues of conventional refrigerator

• Low efficiency ( COP (Coefficient Of Performance) = 0.05 )

Doubling of efficiency is important to gain cost advantage of HTS cable system.

• Short maintenance interval

This refrigerator needed vacuuming every two weeks and replacing parts every 8,000 hours.

Maintenance interval for the power system is required over tree years.

• Capacity is 5 ~ 20 kW (First target is 5 kW)

• COP is 0.1

• Maintenance interval is over 30,000 hours

Target of new refrigerator

NEDO

「Yokohama project」(FY2007 ～ FY2013) Expansion of

HTS cable system

It is necessary of large capacity and

high efficiency refrigerator

High performance refrigerator(2nd Generation)

1st stage 2nd stage 3rd stage Expander

Compressor

Cold BoxCompressor Unit

High performance impeller

Cooling

Water

Compressor Unit Cold Box

LN2

GNe

Cooling

Water

Cooling

Water

Heat

Exchange

Heat

Exchange

1st - 2nd stage

Compressor3rd stage

Compressor expander

MM

Buffer Tank

1st stage

Compressor

2nd stage

Compressor

3rd stage

Compressor

Expander

High speed

motor

High speed

motor

The Cooling Capacity is

5.0 kW at 69 K and 5.8 kW

at 77 K.

The COP (Coefficient Of

Performance) is 0.1 at 77 K

with respect to motor input

power.0.07

0.08

0.09

0.10

0.11

68 70 72 74 76 78

CO

P[－

]

Temperature [K]

Results of performance test

3. DC HTS Power Transmission Line

The losses of DC superconducting power

transmission line are under 1~2 %.

DC superconducting cable enables DC power

transmission with low voltage and large current.

DC power transmission with extremely long

distance and large capacity is possible without

increasing voltage.

Merits of DC HTS Power Transmission Line

Terminal

Cryo-cooler &

Circulation pump

Completed in March 2010

Terminal

Cryo-pipe

Chubu University

Cost Evaluation

Over Head Line HTSC cableXLPE cable

Voltage

Current

Power / Length

Initial Cost

Cooling System

Converter Station

Operation Cost (Loss)

Total Cost

600 kV 300 kV 500 kV

3000 MW / 2500 km

2500 A 3000 A 5000 A

Wire Price

Installation

$500M $500M $450M

- - $2,000M

$250M$750M

Including in initial cost

Including in initial cost

$11,550M

$4,440M

$11,200M

$17,240M

$8,500M

$12,800M

$1,230M

$12,430M

$10,800M

$750~5,000M

$11,550~15,800M

(*2) Electric Power Cost of $0.15/kWh, 30 years operation

(*1)

(*2)

(*1) Direct Burial,

(*1)

Summary

Demonstration test was carried out for year

and successfully finished.

We are successful in developing the high

performance refrigerator for HTS.

DC HTS cable enable long distance power

transmission with low losses.

Thank you