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Progress of, and prospects for, Progress of, and prospects for, commercial applications of UHV commercial applications of UHV 1100kV Transmission System in 1100kV Transmission System in TEPCOTEPCO

2nd International Symposium on International Standards for Ultra High Voltage, New Delhi, January 29-30, 2009

Hiroshi OKAMOTO

TEPCO

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UHV Transmission Lines in TEPCO

〈〈 North-South RouteNorth-South Route 〉 〉 [1993][1993]Minami-Nigata LineMinami-Nigata Line: : 49km49km×2cct×2cct　　　　　　　　　　 (Total Length: 111km)(Total Length: 111km)

Nishi-Gunma Line: Nishi-Gunma Line: 138km138km×2cct×2cct

〈〈 East-West RouteEast-West Route 〉 〉 [1999][1999]Minami-Iwaki LineMinami-Iwaki Line: : 194km194km×2cct×2cct

Higashi-Gunma LineHigashi-Gunma Line: : 44km44km×2cct×2cct

〈〈 North-South RouteNorth-South Route 〉 〉 [1993][1993]Minami-Nigata LineMinami-Nigata Line: : 49km49km×2cct×2cct　　　　　　　　　　 (Total Length: 111km)(Total Length: 111km)

Nishi-Gunma Line: Nishi-Gunma Line: 138km138km×2cct×2cct

〈〈 East-West RouteEast-West Route 〉 〉 [1999][1999]Minami-Iwaki LineMinami-Iwaki Line: : 194km194km×2cct×2cct

Higashi-Gunma LineHigashi-Gunma Line: : 44km44km×2cct×2cct

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UHV System DesignUHV System Design

Secondary arc extinction for fast reclosing, etc.Secondary arc extinction for fast reclosing, etc.

Size reduction of UHV transmission towerSize reduction of UHV transmission tower

Electric and Magnetic field, corona noise, wind noiseElectric and Magnetic field, corona noise, wind noise

Rationalization of insulation coordinationRationalization of insulation coordination

Transmission line Transmission line designdesign

Insulation Insulation designdesign

Solution for network problem peculiar to Solution for network problem peculiar to UHV systemUHV system

Size reduction of substation equipmentSize reduction of substation equipment

Development of highly reliable equipmentDevelopment of highly reliable equipment

Substation Substation designdesign

High Speed Grounding Switch(HSGS)

MOSA, CB with resistor

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Issues to be addressedIssues to be addressedin voltage upgradein voltage upgrade

To reduce annual capital expenditure below a certain rational level,

To ensure flexibility under uncertainty in the development of power plants,

To reduce a risk of degradation of reliability during the construction period for upgrading, and

To shorten the planned outage of transmission lines during the construction.

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Schematic diagram of UHV designed transmission lines

～U5 U1

200km40km50km

140km

～～

～

～

U2

UN

U3

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Option 1

1100kV circuit

550kV circuitU1U5

3 or 4.5GVA

550kV 550kV

1100kV circuit

550kV circuitU1U5

3 or 4.5GVA

550kV 550kV

Only single circuit will be operated at 1100kV and the other circuit at 550kV in the very first stage of the upgrading.

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Studied Issues

a. switching overvoltage induced in 1100kV and 550kV circuits,

b. lightning overvoltage in the substations,c. short circuit phenomena between 1100kV and 550kV

circuits,d. necessity of HSGS in the 550kV circuit to extinguish

secondary arc current after the fault in the circuit,e. operation and maintenance considering outage of eq

uipment,f. protection,g. TRV andh. voltage deviation due to energization and de-energiz

ation

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Option 2Simplified bus configuration may be applied as a cost-effective solution for line U1-U5 only if the subsequent upgrade is not expected over the long term.

U1U5

bypass circuit550kV 550kV

U1U5

bypass circuit550kV 550kV

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Switching Overvoltage Analysis

simplified bus configurationdouble-bus-bar four-bus-tie configuration

U1

U5

U1

U5

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Option 3

Double T connection at U2 S/S, instead of double connection, can reduce the installation cost.

U1U5U2

U3

U1U5U2

U3

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Concluding RemarksTEPCO is now studying the issues for upgrading the operating voltage of the constructed UHV transmission lines from 550kV to 1100kV.

We will finalize technical specification of substation equipment shortly so as to be able to respond quickly and flexibly to future generation developments.

In this context, standardization of the UHV technology is urgently needed.