Asia | September 28, 2021

Korea’s KEPCO commercializes superconducting transmission solution

South Korea, Shingal: KEPCO has developed a cost-effective method to bring superconducting transmission lines and substations into commercial operation.

 

Image source: T&D World

South Korea, Shingal: KEPCO has developed a cost-effective method to bring superconducting transmission lines and substations into commercial operation.

Korea Electric Power Corp. (KEPCO) is the largest electric utility in South Korea and its KEPCO Research Institute has established 10 key strategic technologies, including superconducting cables, which the utility began researching in the early 21st century through a national research fund.

Because of this investment in research, the development and verification testing of superconducting cables for AC and DC applications from 23 kV to 154 kV is now considered proven technology for the utility. KEPCO has taken the next step by using this technology in its first commercial project, the Shingal project.

The Shingal project interconnects the secondary bus bars of KEPCO’s 154 kV Shingal and Heungdeok substations with a 23 kV superconducting cable. This section of the 154 V network was chosen because spare conduits (cable ducts) already existed between the two substations. Therefore, no investment costs would be incurred to construct new conduits for the cable installation.

Because of the high percentage of residential electric customers in its mix, KEPCO needed to increase the supply capacity. However, the conventional method to supply the load increase would involve installing an additional transmission cable or a transformer, at an estimated cost of $3 M.

In contrast, the superconducting cable project was expected to cost $12 M, four times that of the conventional method. However, KEPCO identified opportunities to reduce the cost of the superconducting cable system.

Located 1.1 km from the Shingal substation, the Heungdeok substation is connected by two 154 kV transmission cables. An additional 60 MVA transformer was planned for the Heungdeok substation to supply increased load. However, KEPCO decided to link the secondary bus bars of the two substations with a 23 kV three-core high-temperature superconducting (HTS) cable instead of installing an extra transformer. Connecting the two substations with the HTS cable enabled the substations to share the additional load on the distribution network while eliminating the need to install and cost of a 60 MVA transformer.

By working closely together when siting the 154 kV substation, the utility’s T&D planning organizations were able to optimize KEPCO’s overall investment cost. Because HTS cables can provide the same load-transfer capacity with fewer cables, it was possible to install cheaper conduits rather than having to construct a cable tunnel. The 23 kV switching station at the load centre links the 23 kV HTS cables to the existing distribution cables to supply the load centre. This redesign, from a cable tunnel to cable conduits, reduced the utility’s cable installation costs.

Korea’s first commercial 23 kV HTS ac cable application, the Shingal project was successfully completed in July 2019 and continues to energize the electric grid today.

 

Source: T&D World