The SOO Green HVDC Link will be built along an operating railroad from the Mason City, Iowa area to the Chicago, Illinois area. Placing transmission cables underground within a secure, monitored railroad corridor enhances security compared to traditional overhead lines. Unlike AC transmission lines, underground HVDC cables are insulated and shielded, preventing the emission of fluctuating electromagnetic fields and the generation of induced currents. This modern DC technology is self-contained, highly efficient, and designed to operate safely with minimal environmental impact, making it a reliable solution for energy transmission
The project will use two 5-inch diameters (about the size of a wine bottle), 525KV extruded cross-link polyethylene (XLPE) insulated cables installed in a 3-foot wide by 5-foot deep trench. SOO Green HVDC Link will construct two VSC power converter stations at either end of the 350-mile HVDC line. These VSC stations, which will be the largest ever built in the U.S., will convert Alternating Current (AC) power produced by wind and solar generators in MISO to Direct Current (DC) to enable transmission over the line and then back to AC power for distribution to customers in PJM.
Installing cables in 8-inch conduits enhances accessibility for maintenance and repair, reduces the need for redrilling, and minimizes disruption.
Drain Tiles
SOO Green understands the importance of existing infrastructure, including drain tile, which is integral to Midwestern farming activities. When the underground transmission line route intersects with an existing drain tile, smaller tiles will be cut and capped to allow the trench to be dug and conduits installed. Once the conduits are in place, the tiles will be repaired, and the trench will be filled in with existing topsoil. Depending on the size, current use and flow rate of the drain tile, conduits may be placed underneath larger tiles without cutting.