ZHM 161kV Substation EPC: Ghana Project Technical Overview

ZHM Huawu Steel has completed the engineering, procurement, installation, testing, and commissioning scope for three (3) 161kV / 11kV substation projects in Ghana, West Africa. The substations — designated GP-Chirano, GP-Wassa, and GP-Edikan — serve as grid interconnection points for gas-fired power generation plants, stepping up voltage from generator bus level (11kV) to the national transmission grid (161kV).

1. Project Background and Configuration

The three substations operate under the nominal voltage class of 161kV (equipment rated 170kV) on the high-voltage side and 11kV (generator bus) on the low-voltage side. Each site includes one (1) step-up main power transformer (66/80 MVA, 161kV/11.5kV, YNd11, ONAN/ONAF), provided as Owner-Furnished Equipment (OFE) by TBEA.

The overall EPC scope executed by ZHM included:

▣Detailed engineering and design review
▣Fabrication and hot-dip galvanizing (HDG) of all steel support structures
▣Supply and installation of 161kV Air Insulated Switchgear (AIS)
▣Supply and installation of 11kV medium voltage (MV) indoor switchgear
▣Protection, control, metering, and SCADA/Substation Automation System (SAS)
▣DC power supply, UPS, and auxiliary power distribution
▣Telecommunication via Power Line Carrier (PLC)
▣Complete cable management system (trays, conduits, power and control cables)
▣Lightning protection and grounding grid
▣CCTV, fire detection and suppression, HVAC, and lighting
▣Site acceptance testing (SAT), pre-energization checks, and commissioning support

2. High-Voltage (161kV) AIS Equipment

The outdoor 161kV AIS configuration per substation includes:

SF6 circuit breakers (LW36-161/T4000-40): 170kV, 3150A, 40kA/3s, live tank, single-pole, hydraulic-spring mechanism
Disconnectors (GW16-161DW) and disconnectors with earth switch (JW-161): 170kV, 3150A, motorised
Capacitive voltage transformers (TYD161/√3-0.01H) and busbar voltage transformers (JDQX-161W1)
Current transformers: multi-ratio (3000-1000/5A) with four cores (TPS, 5P20×2, 0.2S)
Surge arresters (Y10W1-144/320W): line side, 144kV/10kA, Class 3
Aluminium tubular busbars (Φ130/116mm, LDRE alloy) and AAAC conductor (630mm²)
Disc insulators, post insulators, and complete hardware fittings (terminal clamps, T-connectors, expansion fittings)

All equipment installation followed IEC 62271 series requirements, with contact resistance checks (<20 μΩ per joint), SF6 gas leak detection (<0.5%/year), and polarity/ratio verification for instrument transformers.

3. Medium Voltage (11kV) System

The 11kV indoor switchgear (circuit breaker type, 40kA/3s, 630A) serves as the generator bus connection point. Additional MV equipment includes:

▣Grounding and auxiliary transformer (250kVA, 11.5/0.415kV, ONAN)
▣Neutral grounding resistor (NGR) cabinet (670Ω/10A)
▣Aluminium tube busbar with insulation (120/100mm diameter)

The ZHM installation scope included all MV connections from generator terminals to the 161kV transformer low-voltage bushings, including control wiring and protection interface.

4. Protection, Control, and SCADA/SAS

The Substation Automation System (SAS) is based on IEC 61850 communication protocol. Key panels and functions per substation include:

▣Line bay control units (CSI-200E BCU) and common alarm panels
▣Line protection (CSC-103 main-I differential + distance; CSC-101 main-II distance)
▣Transformer differential protection (CSC-326) and busbar protection (CSC-150, centralized)
▣Grid energy metering panel with Landis E650 tariff meters (Class 0.2s)
▣GPS time synchronization (CSC-196) and fault recorder cabinet
▣SCADA workstation (PCS-9700) with remote communication to GRIDCo control center

All protection relays were secondary and primary injection tested, with end-to-end GOOSE signal verification and GPS-synchronized event recording (1ms resolution).

5. Power Supply, DC System, and Auxiliary Systems

▣125V DC system: Battery rack, battery charger, DC distribution board (DCDB), and intelligent discharge device

▣415V LV distribution board with automatic bus transfer (ABT)
▣5kVA UPS for communication and control loads
▣Emergency lighting cabinet and full outdoor/indoor LED lighting (including explosion-proof luminaires for battery rooms)
▣HVAC: floor-standing and wall-mounted split air conditioners, plus exhaust fans for battery room ventilation with hydrogen detection

6. Grounding, Lightning Protection, and Cable Management

▣Main grounding grid: 120mm² stranded copper conductor, copper-clad steel vertical electrodes (φ20×2500mm), exothermic welding (Cadweld) at all intersections, target ground resistance ≤0.5Ω (4-pole Wenner method)

▣Soil resistance reducing agent (molecular conditioning agent) applied in high-resistivity areas
▣Lightning protection: air terminals (rods) on gantry frames per IEC 62305 rolling sphere method, down conductors to earth grid
▣Cable trays (150mm and 400mm wide, HDG perforated) with covers, supports (L63×6 angle steel)
▣Power cables (XLPE, 11kV and 415V), control cables (KVV/KVVP2), and fiber optic cables for SAS and CCTV
▣Conduit systems: HDG steel (DN26.9–DN60.3) and PVC for appropriate applications

7. Secondary Systems: CCTV, Fire Detection, and Telecom

▣CCTV: outdoor fixed gun (60m IR, IP66, PoE), outdoor PTZ, indoor dome cameras, 32-channel NVR with 10TB storage, 43” monitor, PoE switches, and dedicated 3kVA online UPS

▣Fire detection and suppression: addressable FACP with smoke/heat detectors, manual call points, horn strobes, hydrogen gas detector for battery room, FM-200 (heptafluoropropane) cabinet system for control room, CO₂ and ABC dry powder extinguishers
▣Telecom: PLC system (ABB ETL 600 carrier transceiver, comb filter, line traps, HF coaxial cable) plus 48V DC power supply

8. Steel Structures and Civil Interface

ZHM fabricated and HDG-coated all structural steel components at its Hangzhou factory using Q235B/Q355B steel per GB/T 13912 (minimum 86μm average coating). Scope includes:

▣161kV line gantry frames (with climbing ladders and ground wire frames)
▣Equipment support columns for CVTs, CTs, circuit breakers, disconnectors, and surge arresters
▣Busbar support columns and post insulators
▣Anchor bolts, embedded parts, and all bolted connections (torque-controlled with calibrated wrenches)

Civil foundations were inspected by ZHM prior to steel erection using a Foundation Acceptance Record (FAR). Column plumbness (H/1000 tolerance) and base leveling (±5mm over 10m) were verified with total station and digital level.

9. Testing and Commissioning Sequence

The commissioning process followed GB 50150-2016 and IEC standards, organized into three stages:

Pre-energization tests (de-energized):

▣Insulation resistance (5kV Megger for HV, 1kV for LV)
▣Contact resistance of all busbar joints and CB main contacts
▣CT primary injection (ratio, polarity, winding resistance)
▣Relay secondary injection (trip settings, time delays, output contacts)
▣Grounding resistance measurement (≤0.5Ω target)
▣SF6 gas purity and moisture (<150 ppm v/v)
▣Transformer vector group, turns ratio (TTR), winding resistance, DAR
▣Battery discharge test (2-hour backup at 80% DoD)

Energization procedure:

▣Written clearance from Owner and GRIDCo

▣Step-by-step energization: 161kV bus → main transformer → 11kV bus → generator bus
▣No-load operation of transformer for 1 hour, verification of CVT/VT secondary voltages (±1%)
▣Synchronization and gradual load increase (25% → 50% → 100%)

Reliability run:

▣72-hour full-load continuous operation test with 4-hour interval logging
▣Post-energization DGA oil sample from transformer


10. Applicable Codes and Standards

All works were executed in compliance with:

▣IEC standards: 60076 (transformers), 62271 (HV switchgear), 61869 (instrument transformers), 60255 (protection relays), 61850 (SAS communication), 62305 (lightning protection), IEEE 80 (grounding), and IEEE 81 (resistivity measurement)
▣GB/DL standards: GB 50150-2016 (commissioning), GB 50169-2016 (grounding installation), GB 50205-2020 (steel structure acceptance), GB 50065-2011 (AC grounding design)
▣Ghana-specific: GRIDCo Grid Code (protection settings, metering accuracy Class 0.2s, SCADA communication protocol), Ghana Energy Commission regulations

Where conflicts existed, the more stringent requirement was applied, and technical queries (TQs) were formally submitted to the Owner/Engineer for resolution.

11. Logistics, HSE, and Quality Management

Logistics (China → Ghana):

▣Sea freight from Shanghai/Ningbo ports to Tema Port (30–35 days transit)

▣Customs clearance (Form M, ECOWAS Certificate of Origin, HS code classification)
▣Inland transport to Chirano, Wassa, and Edikan sites (Western and Central Regions)


HSE measures:

▣Mandatory site induction, full PPE (hard hat, steel-toed boots, hi-vis vest, arc flash face shield where required)
▣Permit to Work (PTW) system for high-risk activities (hot work, confined space, working at height >1.8m with fall protection)
▣Lock-Out/Tag-Out (LOTO) for all de-energized electrical work
▣Minimum approach distance to live 161kV equipment: 2.0m (IEC 61472)
▣Environmental controls: spill containment for oil, SF6 recovery (no venting), waste segregation

Quality management (ISO 9001:2015):

▣Inspection and Test Plans (ITPs) for steel fabrication, HV installation, secondary injection, grounding, and pre-energization
▣Non-Conformance Report (NCR) tracking and closure
▣Final handover documentation: as-built drawings, O&M manuals, test reports, mill certificates, HDG inspection certificates, protection relay setting sheets, and warranties

12. Summary

ZHM Huawu Steel successfully delivered the complete EPC installation scope for three 161kV/11kV substations in Ghana, covering design, supply, HDG steel structures, HV/MV equipment installation, protection and SAS, grounding, secondary systems, testing, and commissioning support. The project was executed in compliance with IEC, GB, IEEE, and GRIDCo standards, with a strong emphasis on safety, quality, and documented methodology.

For inquiries regarding substation EPC, equipment supply, or installation services in Africa or similar regions, please contact ZHM Huawu Steel

1 3D BIM Model Wassa 161kV Substations

2 Chirano Substation Gantry Frame Inlet Outlet Conduct

3 Wassa Substation Gantry Truss PT Lighting Arrester

4 Chirano Power Plant Substation Bird View

5 Edican Sub Station Interconnection Existing 161kV

7 Bus bar Bay Gantry Frameworks

8 Pipe type Bus Bar Factory Production Inspection

9 Tube Bus Bar Container Loadings Delivery

10 Wassa Substation Layout Plan Drawing

11 Prefabricated Busbar Junction Box Air Box

12 Transformer 3P Oil Immersed Outdoor Step Up Onan Onaf

13 LV Tubular Bus Bar From Power Plant Substation

14 HV Tubular Bus Bar Supporting Insulators

15 Prefabricated High Voltage 161kV Air Insulated Swithgear AIS

16 Telecommunication Equipment PLC System

17 Illumination Lighting System Distribution Board

18 Substation BIM Modeling Wassa LV Power Cable Edican Busbar

19 Substation Prefabricated Steel Structures Container Loading

20 Wassa Chirano Substation Foundation Preparation

21 Gantry Frame Insulator Hardwares Erection

22 Busbar Support Structures Gantry Frames

23 Disconnector Earth Swith SGS Inspection

24 Lighting Surging Arrester Installation

25 Substation Grounding System Cad welding Material Preparation

26 Lighting Prection Tower Polyn Pole System SPD

27 Communication Equipment ABB FOX615 CPU Power STM GE Electric Panels

28 5000A Prefabricated Containerized Breakers

29 Secondary System UPS DC Panel DCS Cabinets

30 Conduct Cable Delivery

31 Insulators Clamps Hardwares Delivery Container Loading

32 Substation Steel Structures Container Loadings

Why ZHM Huawu Metal 161kV Substation Constructions ?

Reliable and Customized Designs	Cutting Edge Designing Process	Free Online Price System	Easy Bolt-by-number Assembly
Over Two Decades of Experience	Value For Money	Unmatched in Quality and Craftmanship	Excellent Customer Service

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HOW CAN WE HELP YOU?

ZHM’s world-class team — together with our raw material suppliers and subcontractors — works to solve your most challenging design, engineering, farbrication or construction issues.

Contact ZHM by telephone at +86 135-8815-1981 (wechat and whatsapp) or send us your questions via email to info@zhmsteelworks.com