1. Executive Summary
This proposal provides a comprehensive EPC (Engineering, Procurement, Construction) solution for a 33KV-11KV-0.4KV substation, specifically designed for steel manufacturing plants. The solution covers electrical system design, equipment selection, protection & control, automation systems, and civil works, ensuring high reliability and continuous power supply for steel production. The system adheres to international standards (IEC, IEEE) and incorporates smart monitoring and energy management for remote operation and fault diagnostics, optimizing power safety and energy efficiency.
2. Design Scheme & Execution Process
2.1 Overall System Architecture
The system adopts a three-stage voltage transformation:
First Stage: 33KV → 11KV (Main Transformer)
Second Stage: 11KV → 0.4KV (Distribution Transformer)
Third Stage: 0.4KV power distribution
2.2 Capacity Calculation & Design
Load Calculation (Based on IEC 61363)
Using Demand Factor (DF) and Coincidence Factor (CF):
Total Calculated Load = Σ (Equipment Rated Power × Demand Factor) × Coincidence Factor
Transformer Sizing (Based on IEC 60076, N-1 Redundancy Principle)
Main Transformer Capacity:
S = P / (cosφ × η) × 1.25 (Redundancy Factor)
Distribution Transformer:
Configurations: 2×100% or 3×50% redundancy
Grouped load calculation
Short-Circuit Current Calculation (IEC 60909 Standard)
Three-phase fault current analysis to verify breaking capacity of equipment
2.3 Execution Workflow
Pre-Engineering Phase: Site survey, load analysis, grid data collection
Design Phase: System design, protection coordination, layout planning
Procurement Phase: International tendering, factory acceptance tests (FAT)
Construction Phase: Civil works, equipment installation, cable laying
Commissioning Phase: Individual tests, system integration, protection relay testing
Operation Phase: Energization tests, performance verification, handover
3. Equipment List & System Components
3.1 Primary Equipment System
33KV Switchgear (IEC 62271 Standard)
GIS (Gas-Insulated Switchgear): SF6 insulation, including:
Circuit Breaker (CB)
Disconnector (DS)
Earthing Switch (ES)
Current Transformer (CT)
Voltage Transformer (VT)
Function: 33KV incoming protection, metering, and distribution
Power Transformers (IEC 60076 Standard)
33/11KV Main Transformer: Oil-immersed or dry-type, ONAN/ONAF cooling, with OLTC (On-Load Tap Changer)
11/0.4KV Distribution Transformer: Dry-type, natural cooling
Function: Voltage transformation & power transmission
11KV Switchgear (IEC 62271 Standard)
AIS (Air-Insulated Switchgear) with vacuum circuit breakers (VCB)
Includes: Feeder panels, bus coupler, PT panels
Function: 11KV power distribution & protection
0.4KV LV Distribution System (IEC 61439 Standard)
ACB (Air Circuit Breaker), MCCB (Molded Case CB), capacitor banks, distribution boards
Function: Final distribution & power quality control
3.2 Secondary & Automation Systems
Protection & Control System
Microprocessor-based relays (overcurrent, differential, earth fault)
IEC 61850 communication protocol
Function: Fast fault isolation & system protection
SCADA System
HMI (Human-Machine Interface)
Data acquisition servers
Historical database
Function: Real-time monitoring & data management
Power Quality System
Harmonic analyzer (IEC 61000-4-30)
Reactive compensation (SVG/capacitor banks)
Function: Ensures power quality compliance
Auxiliary Systems
220VDC system
UPS (Uninterruptible Power Supply)
Environmental monitoring (temperature, humidity, SF6 detection)
Function: Ensures control power reliability
4. Equipment Cost Breakdown
4.1 Major Equipment Costs
4.2 Additional Costs
Engineering Design: ~8-10% of equipment cost (~$400,000)
Installation & Commissioning: ~15-20% of equipment cost (~$800,000)
Civil Works: ~$500,000 (foundation, cable trenches)
Project Management: ~5% of total cost (~$250,000)
Total Estimated Cost: $6M–$7M (varies based on configuration)
5. Detailed Execution Steps
5.1 Engineering Phase (8–12 Weeks)
Basic Design:
Grid parameter collection (short-circuit level, earthing method)
Load survey & classification (IEC 60364)
Single-line diagram finalization (single bus sectioned/double bus)
Detailed Design:
Electrical calculations (short-circuit, protection coordination, cable sizing)
Layout design (floor plan, elevation drawings)
Protection logic & control schematics
Design Review:
Internal 3-level verification
Client approval meeting
Utility approval (if required)
5.2 Procurement Phase (12–16 Weeks)
1).Tendering & Procurement:
Technical specifications (IEC-based)
International bidding (EU/Japanese brands preferred)
Technical agreement negotiation
2).Factory Inspection:
Witness testing (e.g., transformer FAT)
Progress tracking
Packaging & transport approval
5.3 Construction Phase (16–20 Weeks)
1)Civil Works:
Substation foundation
Cable trench construction
Earthing grid (<0.5Ω resistance)
2)Equipment Installation:
Transformer positioning (oil processing)
Switchgear assembly
Busbar connection (torque-controlled)
3)Cabling Works:
HV cable laying & termination (IEC 60502)
Control wiring
Fiber optic splicing & testing
5.4 Commissioning Phase (6–8 Weeks)
1)Individual Tests:
CB mechanical tests
Relay calibration
CT magnetization tests
2)System Integration:
Protection coordination tests
SCADA point-to-point verification
Synchronization check
3)Energization Tests:
24-hour no-load run
Load testing (phase verification)
Power quality measurement
5.5 Handover & Training (2–4 Weeks)
1)Performance Validation:
72-hour continuous operation
100% protection accuracy verification
Energy efficiency check
2)Documentation Delivery:
As-built drawings
O&M manuals
Test reports
3)Training Program:
System operation
Preventive maintenance
Troubleshooting drills
Total Project Duration: 12–18 months (varies based on complexity).
Critical Path: Equipment procurement & civil works.
This EPC solution ensures seamless execution from design to commissioning, complying with international standards (IEC/IEEE) for steel plant substations.
