South Fork Offshore Substation

To support a 136 MW offshore wind farm, Kiewit engineered, procured and constructed the first offshore topsides gas-insulated substation in the United States. This project included the design, procurement, fabrication, installation, and onshore commissioning of structures, utilities, high- and medium-voltage components, a geographic information system, cabling, instrumentation, protection and metering.

The South Fork Wind Offshore Substation was built at Kiewit’s 555-acre fabrication yard in Ingleside, TX and was then shipped across the Gulf of Mexico, up the east coast to Rhode Island for installation.

The wind turbine generator (WTG) assets will be interconnected by two 66kV inter-array cable strings, each connecting six WTG assets to a single 138 MW high voltage alternating current (HVAC) offshore substation (OSS). At the HVAC OSS, power from the WTG assets will be stepped up by a 150 MVA transformer from 66kV to 138kV for transmission along an export cable to the onshore substation in East Hampton, connecting to the Long Island Power Authority distribution network. Following energization, Kiewit participated in the tests after program completion to fully demonstrate the offshore substation’s performance as an integrated part of the overall wind farm.