Project Overview
Project Type: Dedicated Primary Electrical Substation for Ultra-Rapid EV Charging Hub
Commissioning Date: October 2024
Location: M1 Motorway Service Area, Leicestershire, United Kingdom
Client: National EV Charging Network Operator
Application: Primary power supply and transformation for a 12-bay ultra-rapid EV charging station (up to 350 kW per charger) and associated service facilities.
Technical Solution
TSTYNICE designed, supplied, and commissioned a complete outdoor 20/22 kV to 0.4 kV compact substation with a total capacity of 2000 kVA, built around a high-performance 1600 kVA dry-type transformer as the core component.
Complete Substation Configuration
1. Primary Incoming Section (20/22 kV)
Incoming Supply: 20 kV / 22 kV nominal, 3-phase, 50 Hz
Incoming Cable: 10 kV grade, 240 mm² copper, XLPE/SWA/PVC (client-supplied, interface designed for)
Primary Switchgear: SF6-insulated Ring Main Unit (RMU)
2 x Incoming Panels (1 active, 1 future spare)
1 x Transformer Feeder Panel
1 x Spare Feeder Panel
Fault-make, load-break switches with earthing
Integrated protection CTs and VT
2. Core Transformation Section
Main Transformer: 1600 kVA Dry-Type, Cast Resin
Model: SCR-1600/20-0.4-UK
Rated Voltage: 20/22 kV ± 2x2.5% / 400-230 V
Vector Group: Dyn11
Insulation Class: F (155°C) / Temperature Rise: 100K
Impedance: 6% (optimized for limiting fault current on LV side)
Protection: IP23 enclosure with IP54 for windings, high-temperature sensors, and fault detection.
Total Substation Capacity: 2000 kVA (1600 kVA dry-type + design headroom for potential future expansion via parallel operation).
3. Low Voltage Distribution Section (400 V)
Main LV Panel: 4000 A rated, copper busbar
1 x 2000 A Incomer Circuit Breaker (ACB) with digital protection relay
12 x 250 A Output Feeders for EV chargers (with 125% diversity factor)
4 x 100 A Output Feeders for auxiliary services (lighting, payment kiosks, convenience store)
Power Quality: Built-in harmonic filter banks (for 5th, 7th, 11th) and automatic power factor correction (APFC) to maintain PF >0.98.
EV Charger Interface: Each feeder equipped with energy metering (MID compliant), contactor, and surge protection device (SPD).
4. Auxiliary Systems & Enclosure
Enclosure: Walk-in, weatherproof, steel kiosk. Dimensions: ~6m (L) x 3m (W) x 2.8m (H).
Cooling: Forced air ventilation system with temperature-controlled fans and air filters.
Monitoring & Control: Integrated RTU/PLC for:
Remote monitoring of transformer temperature, load, and alarms.
Interface with Charging Station Management System (CSMS).
Compliance with UK G99 requirements for generator-type connections.
Safety: Fire detection and suppression system (gas-based), emergency lighting, and anti-condensation heaters.
Key Design Features & Compliance
Ultra-Rapid Charging Optimized: The design accounts for the highly dynamic and simultaneous load of multiple 350 kW chargers, including high inrush currents and significant harmonic content generated by power converters.
High Reliability & Uptime: N-1 capability on LV feeders, redundant cooling fans, and comprehensive monitoring ensure the critical charging infrastructure remains operational.
Space & Aesthetics: Compact, containerized design minimized the footprint at the busy service area. External finish in corporate colours with acoustic treatment to reduce transformer hum.
Full UK Compliance:
Grid Connection: Engineered to ENA EREC G99 for the impact on the distribution network.
Equipment Standards: BS EN 60076, BS EN 62271 for transformers and switchgear.
Safety: Compliant with Electricity at Work Regulations 1989, CDM Regulations 2015.
Efficiency: Transformer meets UK ENA P23 (2021) efficiency targets for dry-type units.
Project Execution
Turnkey Delivery: The entire substation was factory-assembled, wired, and tested before being transported in sections to site, minimizing on-site construction time and disruption.
Rapid Deployment: On-site installation and commissioning were completed within a 10-day planned outage window agreed with the local DNO.
Grid Integration: Full witness testing with the DNO, including protection relay coordination tests, harmonic analysis, and G99 compliance verification.
