Compact Transmission Lines and Line Uprating
The challenges of availability of space for corridor for construction of new transmission lines are getting multiplied day by day all over the world for various reasons like, availability and incremental cost of way-leave clearance or Right of Way(ROW), requirement of wider ROW for conventional EHV/ UHV transmission lines, social and political problems of obtaining ROW etc. In order to overcome these challenges, high capacity compact transmission lines are considered as the most optimum solution. There are many features of compacting and these features are adopted judiciously on a case-to-case basis. The concept of compacting is also adopted in distribution line systems to achieve a number of benefits over and above space optimization.Compact transmission line may be described in brief as a transmission line system which will evacuate much more electrical power utilizing the same ROW or evacuate the same quantum of power with consumption of considerably less space or both i.e. enhanced ratio of Power evacuated to width of ROW while maintaining a considerable degree of reliability and safety.
Design of overhead transmission lines with bare conductors should be done with proper co-ordination of insulating air gap. The minimum air gap clearances are live-metal(phase to earth) clearance and inter-phase(phase to phase) clearance. Conventionally, safe clearances are determined by adding displacement of conductor due to wind, temperature variation etc. with the live-metal and inter-phase clearances. In order to make the line compact, such displacement of conductors needs to be minimized which can be achieved by various means.
Our technical team at Supreme has committed to study this subject with the objective to find the optimum solution for compact lines and transmission line uprating. It has been decided to carry out studies initially on individual solutions as identified below and subsequently identify suitable combinations of more than multiple solutions. Studies have already been initiated by the R&D team of Supreme. The latest technical papers and new technical developments available globally are being considered while conducting in-house studies to arrive at innovative co-created solutions along with concerned utilities. The following technologies aimed at Line Compaction and Transmission Line Uprating are within our capability-
a) For EHV Transmission lines:
i) High Temperature Low Sag(HTLS) conductor
ii) Interphase Spacer
iii) Asymmetrical Bundle conductor
iv) Externally Gapped Line Arrester (EGLA)
v) Insulated Cross-Arm
b) For HV, MV & LV Distribution Systems:
i) Covered conductor
ii) Interphase Spacer
iii) EGLA and Arc Protection Device
iv) Aerially Bunched Cable(ABC)
v) High Voltage Distribution System(HVDS)
Transmission Line Uprating
- Line modification that yields increase in current flow limits is known as uprating.
- Conductors are normally operated below the thermal rating of the line.
- Current flow is increased to operate the conductor closer to its thermal limit.
- Reconductoring the line with HTLS conductor is one of the solutions.