The high-temperature low sag conductors find their application in the transmission sector, distribution sector. A detailed description of the application guide is cited below along with the possible areas where the application of these conductors can be avoided.
Table of Contents
APPLICATION IN TRANSMISSION SECTOR
(a) Those utilities have a large number of transmission lines of 33 kV/66 kV/132 kV etc. These lines are very old and are not able to carry more power. Uprating such transmission lines to carry more power at the same voltage is a viable scenario for the application of HTLS conductors.
(b) If the structures and foundations are in good condition, and the minimum increase in thermal rating in excess of 20% is required, then the application of HTLS Conductors is likely to be a good choice.
(c) Many transmission lines that were once upon a time outside the urban boundaries are now inside the urban boundaries due to rapid urbanization. Changing the tower and/or foundation is almost impossible in such crowded streets. Thus, the application of HTLS conductors to increase the ampacity and reduce the sag of conductors is a viable option.
(d) For short lines, which experience occasional high electrical loads, HTLS Conductors are often an excellent method of uprating. For reconductoring short lines, an increase in electrical losses may not be significant, and the application of HTLS conductors is usually a reasonable and economic option.
(e) For longer lines, application of HTLS Conductors for reconductoring may also be economic, if the frequency and duration of high current loads are less.
(f) In the Intra-State Transmission System, the application of HTLS conductors is expected at 220kV, 132kV, and 66kV levels. The requirement of such a conductor may not be much in Inter-State Transmission System (ISTS), which is dominated by 400kV and 765kV networks. In the case of ISTS lines, the application of HTLS Conductors would be a good substitute for Quad bundle ACSR and AAAC conductors, particularly at 400 kV level when line length is short.
(g) For long river crossing spans, valleys & major highway crossings, and in ravines, the conventional conductor will sag more and result in the excess height of the tower and cost of the foundation. By the application of HTLS conductors, the situation can be addressed.
(h) Application of HTLS conductors in existing transmission/distribution networks is a viable option as it enhances the existing power transfer capability of the line without involving RoW issues.
(i) Due to oceanic and/or industrial pollution, the existing conductors of the line show sizable degradation. It may be necessary to replace such conductors with new conductors, which may be resistant to such vagaries and simultaneously can carry higher currents.
APPLICATION IN DISTRIBUTION SECTOR
Application of HTLS conductors can be considered for use in distribution systems where there is congestion, such as in urban areas, where space is not available for the addition of new overhead lines.
HTLS Conductors can also be useful, if chosen judiciously, to get more benefits in terms of technical losses. However, due to less electrical clearance requirement and proximity from households/buildings, the impact of the operation of HTLS conductors at high temperatures needs to be assessed properly. The demand from the distribution sector is yet to come from utilities because of the high initial investment cost, however, the same can be recovered in a short span of time depending on the load flow and other factors.
APPLICATION IS NOT REQUIRED AND ALTERNATIVE OPTIONS CAN BE EXPLORED
(a) Structures or foundations of the existing line are in poor condition.
(b) The existing line is in good physical condition, and the rating is to be increased by less than 20%.
(c) If the line is above 400 kV, reconductoring with HTLS conductors is not typically required because the existing thermal rating of the line is already much higher than the limits on power flow which is related to the voltage drop of the line and phase shift.
(d) Quad bundle ACSR conductors are being used in HVDC lines not only to meet the requirement of higher current but also for electric fields. Hence, the application of HTLS conductors is not cost-effective for the HVDC system.
