Pokeno substation was a 110/22kV greenfield substation designed for Counties Energy. The substation was required in a relatively short timeframe to support both residential and industrial load growth within Counties Energy’s network. The substation utilises 110kV Gas Insulated Switchgear (GIS) due to space constraints, with two 110kV/22kV 40MVA transformers and a 22kV switchboard with outgoing cable feeders.
Ergo was engaged to provide both concept and detailed design for this project including:
The civil/structural scope consisted of the design and planning inputs required for a 520m2 building with basement for both the 110kV and 22kV switchgear, two external transformer bays with fire walls, site access, stormwater treatment with raingardens and landscape works. Ergo also provided construction support (3910 Engineer To Contract) through the construction stages of the contract.
The electrical design consisted of the 110kV overhead line modifications, 110kV cabling into the substation, selection and integration of the ABB 110kV switchgear (five bays), two 40MVA, 110/22kV transformers and a 13 panel Schneider 22kV switchboard. Ergo also undertook earthing design, insulation co-ordination (provided through a sub-contractor – though we now have that capability in-house), cable thermal modelling, primary equipment specifications, ancillary system design (DC systems, LVAC) and building services.
All protection and automation design for the project was undertaken by Ergo. This included all panel and scheme designs, grading studies, and settings development. The project utilised SEL series relays which had to be interfaced with the 110kV ABB bay management relays. An on-site HMI was also designed for single point control within the control room.