Nicholson Road Pump Station

The Nicholson Rd pump station in Western Australia delivers from 20 Ml/d at 30m pump head up to a maximum of 322 Ml/d at 81.5m pump head. The pump station accommodates future expansion to stage two; up to 300 Ml/d at 220m pump head.

Five variable speed pumpsets were provided for stage one with provision for a sixth pumpset for stage two.

Scope of the commission included architectural, civil, structural, mechanical, electrical and I&C detailed design.

The pump station electrical works comprised:

• 22kV main switchboard, two pump 22kV Switchboards and one 22kV generator switchboard installed indoors
• Five 3.3kV, 1925kVA variable speed drives configured for quasi 24-pulse operation comprising dual secondary dry type rectifier transformers and 12-pulse variable frequency converter all installed indoors
• Two 22kV/433V 160kVA dry type kiosk transformer installed indoors
• Two 3.3kV/22kV/433V 2250kVA/160kVA dry type kiosk transformers installed indoors
• Five 3.3kV 1650kW cage induction motors installed indoors
• Two 2.25MVA standby diesel generators
• One 415V Form 1 type tested switchboard installed indoors
• LV distribution boards located around the pump station site
• Associated electrical services for power, lighting, fire detection and security systems
• High and low voltage cabling
• A common earthing system using four 20m deep hole electrodes, and multiple building reinforcement and grading conductor connections

Getting harmonics right was particularly difficult due to the inner CBD location. This was addressed by use of alternating drives supplied with D d0.25 d11.25 and D d0.75 d11.75 transformers with a 300 relative phase shift to operate as a quasi 24-pulse converter when operated in pairs.