Two new EPC substations to supply gas pipeline compressor stations in Northwestern New Mexico

EPC Substations Project Description:
Total system responsibility for two new 115 kV substations to supply power for new natural gas pipeline compressor stations.

EPC Substations Problems: A major energy company was adding compression horsepower to natural gas pipelines in northwestern New Mexico. Economic analysis indicated that the use of electrically driven compressors would result in lower total costs of operating the new compressor stations. Supplying power to the new compressor motors from the electric utility distribution lines was impractical, but service from 115 kV transmission lines could be provided within the time frame required. Both compressor stations had deadlines for operation to meet contractual and operational constraints.

EPC Substations Design Factors:
Space was allocated by the owner in each of the two new compressor stations for the required 115 kV-13.8 kV outdoor substation. We worked with the owner's engineers and the utility to orient the substations to provide for a minimum angle of the 115 kV overhead lines to the dead-end structures. We further worked with utility engineers to make these "customer-owned substations" conform to utility design standards at the 115 kV level, with special considerations that included de-rating factors for the altitude of the two stations.

EPC Substations Engineering Solutions:
A spare transformer was supplied that could be used in either facility. Relatively small areas were allocated for the electric substations. One substation was made wider to accommodate a spare transformer on a permanent foundation. 13.8 kV insulated cables were routed through buried conduits between the switchgear and the motor control centers, which were outside the substation fence line in the compressor stations.

We also designed buried ground grids to limit step and touch potentials to acceptable levels within each substation, taking into account maximum available fault current and a multi-layer model of soil resistivity for each substation.

EPC Substations Scope:
Design, supply and install two 115 kV-13.8 kV substations, each including steel structures, 115 kV instrument transformers, 115 kV air break disconnect switches, 115kV circuit switcher, 33 MVA 115-13.8 kV transformers (one in service at each station plus one spare), 15 kV metal-clad switchgear, substation relaying, ground grids and outdoor lighting. We provided all engineering, project management, labor, testing and start-up of each substation to meet the schedule of in-service operation.