Investigation of thermal behavior, sag and economic aspect of overhead lines conductors under different conditions and loadings

• Main Author: Al Darraji Mohammed Sfayyih Barih
• Format: text::Thesis
• Language: English
• Published: 2023
• Subjects: Thermal behavior, sag and economic aspect

As electricity demand grows, existing transmission lines have reached the critical limits of allowable thermal temperature and ampacity. However, building new transmission lines and selecting new corridors are complex tasks, and the best option to reduce the expansive construction cost and to obtain an excellent economic revenue is by replacing the existing transmission line conductors the aluminum conductor steel reinforced (ACSR) with a new type of conductors the aluminum conductor composite core (ACCC), at the same size and weight, or less, to avoid any modifications in tower foundation or structure. The ACCC conductor has positive advantages such as higher temperature, lower sag, and higher ampacity when compared with the conventional conductor. Moreover, the ACCC conductor has higher economic benefits when replacing the existing ACSR conductors with the ACCC conductors or if selecting it directly for the new OHTLs construction. The mechanical properties of conductors are associated with the amount of carrying ampacity; if the ampacity increases, the thermal stress will also increase, and these features influence the elasticity and sag of conductors. The dissertation calculated steady-state thermal stress and transient thermal for the ACSR (Hawk) and ACCC (Lisbon) conductors based on the IEEE Std.738. Found that the wind speed and ambient temperature have a real influence on the performance of the conductor, where the ACCC has shown a perfect performance under various conductor temperatures and can carry the current twice more than the ACSR as cleared in the calculation of ampacity for both ACSR(Hawk) and ACCC (Lisbon). Moreover, the ACCC conductor has a lower sag and good tensile strength compared with the ACSR conductor owing to is includes stiffness carbon-fiber core, which works as a backbone of the conductor and has a lower thermal expansion coefficient. The Economic benefits are calculated for both ACSR (Hawk) and ACCC (Lisbon) conductors and found the power losses in the ACCC conductor are lower than in the conventional conductor, owing to the absence of the steel core on its formation. Also, the ACCC can carry additional power more than the ACSR without needing a modification on the tower foundation or structure. The percentage of improvement can be up to 95% calculated with the CTC Global company software.