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McCoy Solar 34.5 kV Collection System

California, USA


Renewable Energy, Transmission & Distribution

Project Highlights

  • Overhead 34.5 Distribution Design
  • Overhead 230 kV Transmission Design
  • Substation Design
  • Engineering Studies

The McCoy Solar Energy Project consists of photovoltaic (PV) arrays connected to inverters for a total capacity at full generation of 270 MW. The project is located in Riverside County, California. The Solar project is interconnected to Southern California Edison’s (SCE’s), 230 kV transmission system approximately 13.3 miles west of Blythe, California to SCE’s 230 kV Colorado River Substation, the point of interconnection (POI). The 11.37 miles of 230 kV, 954kcmil ACSR “Cardinal” bundled (2) conductor transmission line is connected to the project substation, Black Creek Substation located on the project site. The substation has two (2) 3034.5 kV, 84/112/140 MVA station transformers with four (4) collection 34.5kV feeder circuits connected to each transformer.

The AC collector system commences from the eight pad mount sectionalizer cabinets for each feeder circuit located north and just outside the Black Creek Substation fence. Six (6) 34.5 kV feeder circuits extend overhead to the north a maximum distance of 8,101 feet and the other two overhead circuits proceed east a maximum distance of 5,240 feet with each circuit connecting to a pad mount 34.5 kV photovoltaic combining switchgear (PVCS) near the collection field. The six (6) overhead circuits extending north are supported by custom weathered steel foundation structures provided by Keystone. Hendrix, Spacer Cable System uses covered conductors, 1272&795 kcmil sizes, 3 phase spacers for each circuit and multi-varietal of pole brackets supported by Hendrix messenger wire. This allowed construction of one pole line with the achieved multi-circuit overhead configuration. Hendrix provided the material attributes to ECI engineers that successfully modeled the overhead line in PLSCADD. The two overhead circuits toward the east were framed with Hubbell horizontal polymer insulators on Keystone structures.

Each circuit has underground parallel cable sections from the overhead line at both ends of the PVCS and substation sectionalizer installed direct buried in a trefoil configuration with thermal backfill for heat dissipation. The cable is rated at 35 kV, 345 mils of insulation, tree retardant cross linked polyethylene (TRXLPE) insulation type, aluminum conductor with copper concentric neutrals, MV105 type. Cable sizes varied from 1250 to 500 kcmil provided by American Wire Group.

ECI engineers modeled the circuits and performed multiple engineering studies verifying the project requirements of voltage drop, losses, insulation ratings, fault current and conductor ampacity for the overhead and underground lines. ECI Design Engineers provided QA audits and QC checks for 85 drawing sheets created by ECI Designers.

National Power Line construction management and crews provided a seamless construction installation and commissioning along with Border States procurement of project materials.



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