Double Circuit Line Research Paper

CHAPTER 1
INTRODUCTION
INTRODUCTION The continuous increasing the demand of electricity causes to build up a new transmission line with higher rating of voltage to reduce power losses. Transmission line with higher power transfer capability means higher rating of voltage and current. Electromagnetic field is produced due to voltage and current. Electric field is directly proportional to the voltage of line and magnetic field is directly proportional to the current of transmission line. Research claims that working or living near to the high voltage power line becomes potential hazard to human. Recent investigation shows that magnetic flux density beyond limit causes cancer. World Health Organization (WHO) established guidelines for the magnetic

So it is necessary to construct new transmission line. 3 phase double circuit line is commonly used for transmission line. In 3 phase double circuit transmission tower 3 phase are commissioned both side of transmission tower. 3 phase double circuit line can carry double power compared to 3 phase single circuit line. The configuration of 3 phase double circuit line is shown in figure 1 below. Fig. 1: 3 phase double circuit line `In this report different combination of 3 phase double circuit line are analyzed considering magnetic flux density at ground level. In one case magnetic flux density is measured at tower foot area and in all other cases magnetic flux density is measured at mid-span level.
Four different combination of transmission tower are as following Conventional-conventional case, Conventional-converted case, Converted-converted case, Compact-compact case.
These all combination are explained as below.

3.1 Conventional-conventional case In Conventional-conventional combination two 3 phase double circuit transmission tower are along with each other. This combination is shown in below

In this study combination is considered as shown in below figure. Distance between the center line of tower is 35 m. For analysis at one center line distance is taken 0 m. Fig. 7: parallel line considered in this study 4.1 Conventional-conventional case Figure 8 shows the plot between magnetic flux density in micro Tesla versus meter. The star curve represents a single line alive and the second line is dead, while the solid line represents both lines alive. In both cases two peaks of magnitude of 11 µT just outer most of the conductor. Here one thing is interesting that higher peak density is found far from the center line of tower.

Figure 9 shows the magnetic flux density at mid-span level when both line are energized. In this case two of the four peaks exists between two towers and another two peaks at magnitude at 24 µT near the outer most of the conductor. Comparing both cases, higher flux density is found at mid-span level. Mid-span case is taken as reference case for comparison with other combination. Fig. 8: Conventional–conventional line; flux density distribution at tower