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E.H.V TRANSMISSIONPresented by:

Soumya Khatua

H.I.T

08/EE/60

PRESENTED BY: SOUMYA KHATUAELECTRICAL ENGINEERING08-EE-60

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

INTRODUCTION:The main function of any transmission system is transfer power from a place to

another place or from a network to another network. . Any transmission system consists terminal substations,transmission lines and

intermediate substations. The increasing need of transmission of greater power led to continuous

increase in the transmission voltages.By the urge Extra High Voltage tran-smission is introduced. .. .

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

HISTORY:In 1886 in Great Barrington, Massachusetts, a 1 kV alternating current (AC) distr-

ibution system was first installed.

urt.

The first transmission of three-phase alternating current using high voltagetook place in 1891 during the international electricity exhibition in Frankfut. ..A 25 kV transmission line ,approximately 175 km long connected between

Lauffen on the Neckar and Frankfut .

In India after 1970 trend of using transmission voltageshigher than 300kv came(known as Extra High Voltage). ....

Now Ultra High Voltage transmission(above 765kv) is .used over long distances. ..

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

NECSSITY OF EHV TRANSMISSION: TO REDUCE THE ELECTRICAL LOSSES:P=V*I,P=CONSTANT, V ,

I , Cu loss=

TO INCREASE TRANSMISSION EFFICIENCY:

Transmission efficiency=

Line losses Transmission Efficiency

TO REDUCE MATERIAL OF CONDUCTOR:

Conductor material

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

TO INCREASE TRANSMISSION CAPACITY:

Transmission capacity

P=Power expressed as: , (Vs.Vr)

REASONS OF ECONOMY & SAFETY:

Generating s tation s are located in remote area .

EHV tran s miss ion us ed f or tran s miss ion of hu ge block s of power over long dis tan-ce s f rom the s e power plant s to load centre s.

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

TO INCREASE LOAD CARRYING CAPABILTY:

Load carrying capability is represented by SIL(Surge Impedance Loading).

SIL= As V SIL (Load carrying capabilty)

Voltage Class Loadability (@300Miles)

Reach (@1500 MW)

765kV Single Circuit 2200 2400 MW 550 Miles

500kv Single Circuit 900 MW 140 Miles

345kV Single Circuit 400 MW 50 Miles

TO REDUCE THE RIGHT OF WAY:

In some countries right of way are paid for at rate proportional to the total widthof the transmission lines. Using EHV transmission the total width of transmissionlines reduces as well as Right Of Way. ....

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Insulations are required to protect transmission from voltage surges dueto internal causes(switching operations) Or external causes (lightning

etc). . ......................................

INSULATION REQUIREMENTS:

Lines are protected by using ground wires and using Auto reclosingcircuit breaker. ...

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

HEAVY ROBUST SUPPORTING STRUCTURE:EHVT system has robust supporting structure due to:

Using bundled conductors

Larger air & ground clearences

Considerable dynamic forces due tobroken conductor ...

Transmission line made of fabricated steel

o Due to robust construction problems of transportation and erection arise. .

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

LIMITATIONS & DESIGN ASPECTS : STABILITY CONSIDERATION:

Maximum steady state transfer of power takes place in practical casewhen load angle=20 to 30 degree

, X=0.3475 ,

P=1.43 = .

ENVIRONMENTAL & BIOLOGICAL ASPECTS:

Low frequency magnetic field affects on cellular metabolism.

Current density over 100mA/ Causes health hazards.

Safe ground clearance of 20m at mid span of tarnsmission line.

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ELECTRICALENGINEERINGDEPARTMENT

HALDIA INSTITUTE OF TECHNOLOGY

SERIES COMPENSATION:To increase the performance of EHV transmission .

P= , P = , P

SHUNT COMPENSATION:To inject reactive power & control receiving voltage.

To neutralize the Ferranti Effect.

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REFERENCE:

Books & Notes:

A course in Electrical Power by J.B.Gupta

Notes on Power System given by B.D.B sir

Websites:http://www.wikipedia.org

http://www.google.com/ig

http://www.ee.iitm.ac.in

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THANK YOU