Abuja Transmission Ring Scheme Lot 5: EPC of 132 kV Substations and Underground Cable

Nigeria’s capital region has faced longstanding transmission constraints and electricity supply shortages. The Abuja Transmission Ring Scheme aims to strengthen the regional grid, with LOT 5 providing key substation infrastructure to support power delivery to Kuje, Dafara, Wumba-Lokogoma and nearby areas. The project combines challenging hillside construction conditions with stringent engineering review requirements and complex high-voltage protection and control schemes.

• Complex hillside terrain

  Significant elevation differences at both sites required extensive excavation and backfilling, together with slope protection, retaining structures and drainage systems to ensure long-term site stability.

• Stringent engineering review

  Detailed reviews of site layouts, platform elevations, foundations, gantry structures and drainage required repeated design optimization to balance terrain constraints, structural stability and construction feasibility.

• Complex 132 kV protection and control

  The breaker-and-a-half configuration at both substations required coordinated protection, interlocking, breaker-failure protection and auto-reclosing logic. Comprehensive verification was essential to ensure correct interaction between primary equipment and secondary systems.

• Integrated hillside civil engineering

  Sieyuan coordinated site grading, earthwork balance, slope stabilization, foundations and drainage to address the elevation differences at both sites. This integrated approach supported site stability and equipment installation while accounting for construction constraints.

• Coordinated civil and electrical design

  Civil and electrical interfaces were reviewed together throughout the engineering process. Site layouts, equipment foundations, gantry structures and cable routes were optimized in response to client and consultant reviews, helping improve constructability and reduce potential interface conflicts.

• Integrated protection and control engineering

  Sieyuan coordinated protection, control, interlocking, breaker-failure protection and auto-reclosing logic for the 132 kV breaker-and-a-half schemes. Progressive verification at string, bay and system levels supported the coordinated operation of primary equipment and secondary systems during commissioning.

• Integrated equipment supply and EPC coordination

  Sieyuan supplied major equipment, including power and earthing transformers, circuit breakers, disconnectors, instrument transformers, surge arresters, protection and control systems, and AC/DC systems. Engineering, procurement, equipment supply and site activities were coordinated across Kuje and Wumba to manage technical interfaces and support parallel implementation.

• Two 132/33 kV AIS substations
  Kuje: 3 × 60 MVA; Wumba: 2 × 60 MVA.

• 132 kV breaker-and-a-half configuration
  Coordinated protection and control engineering for complex high-voltage switching schemes.

• 6 km underground cable connection
  Associated 132 kV infrastructure linking the project into the wider transmission network.

• Integrated EPC delivery
  Primary and secondary equipment supply combined with hillside civil engineering and multi-site project coordination.