Saco Valley Substation Upgrade

TRC supported this project to improve the reliability of electricity in northern New England by providing design, construction oversight and commissioning services for the installation and protection of a Phase Shifting Transformer.



Public Service of New Hampshire

Project Location

Conway, New Hampshire

Awards & Recognition

TRC Project of the Decade Award

TRC was responsible for the upgrade of Saco Valley Substation as part of the White Mountains Project, which included a major upgrade of two other stations in the region. This upgrade allowed PSNH to change their current operating mode by actively controlling power flow through 115kV Line Y138 by the addition of a 115kV:115kV Phase Shifting Transformer (PST) at Saco Valley Substation. Additional improvements to the White Lake, Beebe River, and other Substations provide system stability throughout the White Mountain Region.

This upgrade involved doubling the size of the existing yard, installation of new gas insulated breakers and buswork to accommodate the addition of the PST and improvements to the other lines at the station. Redundant primary and secondary protection systems were installed to provide relay protection for the PST, 115kV bus, and the other line terminals at the station. In order to provide SPCC compliance and environmental protection the transformer containment design utilizes a shallow, rock filled geosynthetic lined pit surrounding the PST foundation. This design added the advantage of simplifying construction and reduced the overall project cost.

TRC built a new control house to accommodate the line protection relays, SCADA, Digital Fault Recorder, Frequency Meter and related equipment dedicated to the Transmission (115kV) portion of the station. The system upgrades also included new station service with the addition of a propane fueled emergency generator. TRC provided P&C and Substation design services, P&C Construction oversight, High Voltage Testing and Commissioning services for this upgrade to Saco Valley.

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