[ ] POWER SYSTEM PLANNING AND DESIGN TITLE : DESIGN OF EHV TRANSMISSION LINES & BUNDELED CONDUCTORS IN EHV LINES. UNIVERSITY : GUJARAT TECHNOLOGICAL UNIVERSITY COLLEGE : VADODARA INSTITUTE OF ENGINEERING DEPARTMENT : ELECTRICAL ENGINEERING [E.E.– I] SEMESTER : VIII COMPILED BY : [ JESTY JOSE ] [ JOBIN ABRAHAM ] GUIDED BY : PROF. PRINCE SINH [ELECTRICAL DEPARTMENT] [ELECTRICAL DEPARTMENT] 1

 Outline  Introduction Introduction  Advantages of EHV lines Advantages of EHV lines  Disadvantages of EHV lines Disadvantages of EHV lines  Design Considerations of EHV lines Design Considerations of EHV lines  Selection and spacing of bundled conductors Selection and spacing of bundled conductors  References References2

 Introduction  With the increase in transmission voltage, for same amount of power to be transmitted current in the line decreases which reduces I 2 R losses. This will lead to increase in transmission efficiency.  With decrease in transmission current, size of conductor required reduces which decreases the volume of conductor.  The transmission capacity is proportional to square of operating voltages. Thus the transmission capacity of line increases with increase in voltage.  With increase in level of transmission voltage, the installation cost of the transmission line per km decreases. 3

 Advantages  Reduction in the current.  Reduction in the losses.  Reduction in volume of conductor material required.  Decrease in voltage drop & improvement of voltage regulation.  Increase in Transmission Efficiency.  Increased power handling capacity.  The no. of circuits & the land requirement reduces as transmission voltage increases.  The total line cost per MW per km decreases considerably with the increase in line voltage. 4

 Disadvantages  Corona loss & radio interference  Line supports  Erection problems  Insulation needs  The cost of transformers, switchgear equipment's & protective equipment's increases with increase in transmission line voltage.  The EHV lines generates electrostatic effects which are harmful to human beings & animals. 5

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 Design considerations of EHV lines 1. Choice of voltage level. 2. Choice of the method of grounding. 3. Choice of conductor. 4. Calculation of corona losses. 5. Choice of conductor. 6. Choosing the number and type of insulators. 7. Insulator contamination. 7

 Design considerations of EHV lines {cont.} 8. Voltage regulations of lines. 9. Line losses. 10. Stability considerations. 11. Insulation coordination. 12. Reliability. 13. Types of towers, suspension strings, etc. 14. Electrostatic field effect. 8

 Selection and Spacing of conductors  For EHV above 400kV bundled conductors are used. 9

 Selection and Spacing of conductors {cont.}  The inductance of a 3-phase transmission line per meter is  The capacitance of a 3-phase transmission line phase-to- neutral is 10

 Selection and Spacing of conductors {cont.}  The Surge Impedance is (SI)  The Surge Impedance Loading is (SIL) 11

 Selection and Spacing of conductors {cont.}  The percent increase in the line capability is 12

 Selection and Spacing of conductors {cont.} 13

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 References 1. M V Deshpande “Electrical Power System Design”, McGraw-Hill Education (INDIA) Pvt. Ltd., 39 th Reprint : 2015, ISBN : ehv-ac-transmission ehv-ac-transmission ehv-ac-transmission16

ANY QUESTIONS? SUGGESTIONS ARE WELCOME! 17