Energy utility expands grid for renewable energies

Due to the positive development of the wind farms in Fläming (Brandenburg), the existing grid infrastructure has been undergoing expansion since January 2017. A 110 kV cable connection now leads from the Petkus substation to the Schönewalde Süd grid connection point. In this project, the grid operator is using the high-temperature-resistant protective pipe ege-com^® Macroduct High-T PP and PE.

During the installation of a conduit system for a 110 kV HT 1270 cable from the Petkus substation (UW) to the Schönewalde Süd grid connection point (NVP), the installation was carried out by the company Bohlen & Doyen Wiesmoor – using both open-cut and trenchless construction methods. A pipe route of over 25 km was completed using the open-cut method. The points were connected to each other along the planned route. The route consists of two protective pipe systems, with one prepared and one installed cable system. The cable system is installed in a flat formation with three cables side by side, while the empty system is installed in a triangular formation. Areas where open-cut construction is not possible, such as streams, ditches, roads, and river crossings, are crossed using HDD drilling. A 110 kV HT 1270 cable from NKT is used for the installed cable system, which is pulled into the conduit system. The goal is to achieve pull-in lengths of up to 1,800 m.

For the open-cut installation, the ege-com^® Macroduct High-T PP system with push-fit sockets in the dimension 200 x 9.1 mm was used. It is a protective pipe for high and extra-high voltage cables that features increased thermal stability to withstand high thermal stresses. Its easy handling allows for economical installation. “This made it possible to achieve installation rates of up to 300 m in the composite system, i.e., 150 rods per day. A positive aspect during construction was the very easy and fast socket assembly, where the factory-applied insertion depth marking proved to be very helpful,” explains site manager Paul Eirich. The long-socket design offers increased safety. This is particularly advantageous for angular deflections, such as those occurring in curved sections.

The undercrossings were carried out using the HDD method. The drilling lengths were up to 220 m at a depth of up to 7 m and a drilling radius of approximately 60 m. For the HDD drilling, the ege-com^® Macroduct High-T PP pipes with dimensions of 225 x 13.4 mm were joined using the butt-welding process. During welding, the internal bead was removed without damage to avoid any impact edges for the power cable to be pulled in. All necessary accessory components were supplied by egeplast as a system provider – these include double push-fit sockets (long version), transition pieces, E-sockets, slip-on couplings, end caps, and socket covers, as well as seamlessly drawn bends. Thanks to the productive cooperation and smooth logistics, the project was successfully advanced.