Background: The Stevin Project
The current 150-kV grid in the coastal region of Belgium needs to be upgraded to meet future energy needs. The Stevin project, a new 380-kV connection between the coast and the existing 380-kV backbone grid, is aimed at addressing this issue. Figure 38 shows the line route.
Figure 38. Stevin project overview
The overhead lines will make use of existing corridors. The line consists of three sections, as follows:
- A 380-kV line will be reconductored with two circuits of HTLS twin-bundle conductors. This will result in each circuit being uprated to 3000 MVA.
- A new 380-kV line will be built in two sections. For both line sections, a compact 380-kV tower design with insulated cross-arms will be used.
- One will be parallel to the route of an existing 150-kV overhead line. In the other, Elia will partly reuse an existing 150-kV overhead line corridor.
Focus on the Reconductoring Project
The existing 380-kV line between Zomergem and Eeklo Noord is to be reconductored with a twin-bundle HTLS conductor configuration, so that both circuits will be able to uprate the line up to 3000 MVA for each circuit. One circuit will be equipped with Nexans Lo-Sag 850/87.
Options Evaluated and HTLS Selection
Different solutions (ACSS, Lo-Sag, ACCR, and ACCC) were examined. Because of a change in regulations concerning the application of an extreme wind loading criterion in the design, only compact solutions with a low drag coefficient could allow for the towers to be reinforced and not replaced. The Z-shaped wire was chosen. Nexans Lo-Sag was one of the selected solutions.
Qualification Process
As part of the qualification process, the Nexans conductor was subjected to an intensive testing program between February and August of 2015. The conductor was installed in 2016.