HV underground transmission line design for the Burnham Taylor project

The expansion of the underground bulk power transmission system into downtown Chicago requires balancing the need for continuity of service, risk avoidance in the design and operation of the lines and substations, while overcoming the significant obstacles in terrain and infrastructure for the design and installation of the new high voltage underground circuits. The conceptual design for the addition of two 345 kV cross linked polyethylene (XLPE) cable circuits and the modification of the existing 345 kV high pressure fluid filled (HPFF) transmission infrastructure was a challenge in the selection of route, design of the conduit systems, and circuit design. The objectives for the project were to maintain the balance between a reliable and robust design that would minimize disruption of traffic during the installation of the conduit and cables. The paper will present the approach and method for the design of the transmission system and highlight the set of decisions made in the final design of the HV transmission system expansion.