Côte d'Ivoire – Community Power Supply Network Optimization Project: 33 kV to 11 kV Feeder Step-Down Solution

Project Overview

Project Type: Medium Voltage Distribution Network Voltage Level Conversion
Commissioning Date: Q2 2025
Location: Dabou Region, Côte d'Ivoire
Client: Compagnie Ivoirienne d’Électricité (CIE)
Objective: Convert existing 33 kV lines to 11 kV distribution voltage to provide standardized power access for 10 rural communities.

Technical Solution

TSTYNICE delivers a complete 33/11 kV step-down substation solution to transform existing 33 kV feeders to 11 kV, providing standardized power input for downstream distribution transformers (11/0.4 kV) serving 10 communities.

Core Equipment Configuration

• Main Step-Down Transformer:

• Model: SFSZ11-5000/33

• Capacity: 5 MVA (sufficient for peak load of 10 communities)

• Voltage: 33 ± 2×2.5% / 11 kV

• Cooling: ONAN/ONAF

• Vector Group: YNyn0+d

• 33 kV Side Equipment:

• 33 kV SF6 gas-insulated switchgear (incoming, transformer, metering panels)

• Surge arresters and protection system

• 11 kV Side Equipment:

• 11 kV metal-enclosed switchgear (10 outgoing feeders, 2 reserved for expansion)

• Automatic reactive power compensation (±1.5 Mvar)

• Control System:

• Microprocessor-based integrated protection relays

• SCADA remote monitoring system

• Fault recorder

Community Distribution Configuration

• 11/0.4 kV Distribution Transformers:

• Model: S13-M-100/11

• Capacity: 100 kVA × 10 units

• Mounting: Pole-mounted

• Protection: IP54

Technical Features

Adaptive Design

1. Voltage Compatibility:

• Main transformer with on-load tap changer (±8×1.25%)

• Tolerates ±10% voltage fluctuation on 33 kV side

• 11 kV output accuracy ±2%

2. Rural Grid Optimization:

• 33 kV to 11 kV conversion reduces line losses by ~40%

• Optimal 11 kV distribution radius: 8-12 km

• Low-resistance grounding system improves supply reliability

3. Climate Adaptation:

• Equipment corrosion protection: C4 (tropical marine climate)

• Lightning protection: Class I

• Special anti-humidity and anti-mold treatment

Smart Features

1. Remote Monitoring:

• Main substation equipped with DTU

• Real-time load monitoring for each community transformer

• Automatic operational report generation

2. Protection System:

• Three-stage overcurrent protection

• Differential protection (main transformer)

• Earth fault protection

3. Energy Efficiency Management:

• Transformer operational efficiency > 98.5%

• Automatic power factor correction

• Load optimization and distribution function

Project Execution

Implementation Plan

• Design Phase: 8 weeks (including site survey, system calculations)

• Equipment Manufacturing: 16 weeks

• Installation & Commissioning: 8 weeks

• Training & Handover: 2 weeks

Technical Benefits

1. Improved Power Quality:

• Voltage compliance rate increased from 78% to 95%

• Power supply reliability improved to 99.6%

• Harmonic content < 3%

2. Energy Efficiency Improvement:

• Comprehensive line loss rate reduced to 6.5%

• Power factor maintained above 0.95

• Transformer load rate optimized to 65-85%

3. Operational Optimization:

• Fault location time reduced to within 30 minutes

• Remote operations reduce on-site inspection frequency

• Implementation of preventive maintenance

Socio-Economic Benefits

1. Expanded Coverage:

• Provides electricity to ~5,000 households across 10 communities

• Supports small commercial and industrial development

• Provides stable power for schools and clinics

2. Cost Savings:

• Reduces diesel generator usage

• Lowers end-user electricity costs by ~30%

• Reduces operation and maintenance costs by 25%