Many downtown and urban utilities face the challenge of limited availability of real estate for new or expanded substations. This creates a premium for available space.
Due to the electrical resistance and loss characteristics of copper and aluminum conductors operating in AC networks, bulk power is transmitted at high and extra high voltage levels (HV/EHV) of ≥138 kV and relatively low currents of ≤ 1.5 kA. One of the largest occupants of a substation footprint is a large high voltage transformers and other high voltage transmission equipment. How does HTS cable technology help alleviate this problem?
HTS cables operating at distribution voltage levels and much higher currents can transmit the same amount of power (megawatts, MW) as these conventional HV/EHV circuits. The advantage for HTS at lower voltages is that the large HV/EHV transformers and other equipment are no longer needed in the downtown distribution substation. This directly affects the required substation footprint is such applications.
HTS cables at distribution voltages allow the utility to relocate the transmission to distribution step-down transformer to other locations where real estate availability constraints may not be as severe.
This is the application scenario for the HTS Triax cable operating at AEP in Columbus, OH [link to project page]. The 13.2 kV and 3.0 kA rated HTS cable is taking the place of conventional 138 kV connection to adistribution substation, allowing the 138/13 kV transformer to be located away from the distribution bus.