Qinghai-Tibet Power Transmission Network Project—Super OPGW ( Highest Altitude, Large Temperature Difference,Ultralow Transmission Loss)


Known as the “mission impossible” project of Qinghai-Tibet Power Transmission Network Project is yet another star project in the Western Development Plan of China after Qinghai-Tibet Railway. The project boasts several world wonders in power transmission industry: the highest altitude, the longest frozen land zone, the fragile ecological conditions.

Facing up to the severe conditions like high altitude, extreme low temperature, huge day-night temperature change, strong wind and sand-storm, OPGW products of ZTT OPGW must meet the following challenges:

Ultralow Transmission Loss:The conventional  fiber loss of G.652D is between 0.191dB/km and 0.199dB/km; the OPGW firstly adopted ULL ultralow-loss fiber in China, and after a lot of research, finally achieved the fiber loss less than 0.18dB/km, and an average of 0.172dB/km. This has satisfied the requirement of ultralow fiber loss of the overlength station spacing.


Excellent Ultralow Temperature Performance: This project is the first attempt at home and aboard, which requires the change of fiber loss should be less than 0.01dB/km while the ultralow temperature is between -55℃ and -60℃. Furthermore, the change of fiber loss should be not more than 0.01dB/km ranging from -55℃ to +65℃. After the selection of the filling gel to optical fiber and the design of fiber excess length, the change of fiber loss is less than 0.01dB/km while OPGW is under the temperature range from -60℃ to +80℃. Nevertheless, under normal circumstances, the requirement of additional loss of optical fiber is 0.1dB/km while the temperature is -40℃. Consequently, ZTT OPGW has fully satisfied all the technical requirements of Qinghai-Tibet Project. So far, ±400kV DC Transmission Line Network Project from Golmud to Lhasa has already finished and all the technical indicators are excellent simultaneously.


High Altitude Anticorona Performance: The paramount of the project is 5300 meters high, which presents severe requirements for anticorona performance of OPGW and hardware fittings. In the light of these requirements, ZTT has developed OPGW fittings especially for the severe conditions of high altitude and ultralow temperature. In addition, a series of measures have been taken to guarantee the surface, edge and terminal of the products to avoid the possibility of point discharge Meanwhile, these have been taken to strengthen the rubber elements to achieve long lifetime and high altitude anticorona performance..