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MTR Corporation UPS Project: High-Reliability Power Case for Rail Transit
Ⅰ. Project Overview
1.1 Background of Hong Kong Metro System
- MTR Corporation operates one of the world’s busiest metro networks. As of 2025, the rail network covers Hong Kong Island, Kowloon, New Territories, and the Airport Express, with a total mileage of 258 km and over 6 million daily passenger trips.
- Its low-voltage systems include 13 subsystems such as communication, signaling, and integrated monitoring, all requiring Class I load power supply protection.
1.2 Core Power Supply Requirements
- High Reliability: The signaling system (ATC/ATS) has a power outage tolerance of <10ms, or it will trigger emergency train braking.
- Environmental Challenges: High temperature, humidity, and dust pollution in underground stations.
- Energy Efficiency: Must comply with Hong Kong’s Building Energy Efficiency Ordinance (BEA), requiring a 20% improvement in energy efficiency standards for public facilities.
Ⅱ. Core Challenges
2.1 Power Quality Risks
- Harmonic Interference: Variable frequency drive loads cause THDi (Total Harmonic Distortion of Current) to reach 8.2%, affecting signaling system control accuracy.
- Instantaneous Overload: The starting current of shield door drive motors reaches 12 times the rated value, easily triggering protection shutdown in conventional UPS systems.
2.2 O&M Management Pain Points
- Decentralized Deployment: Independent UPS systems at each station result in a fault response time of over 3 hours.
- Battery Aging: Lead-acid batteries have a cycle life of only 3,000 times, with an annual replacement cost exceeding HK$12 million.
2.3 Energy Efficiency Bottlenecks
- Inefficient Operation: Traditional UPS systems have an efficiency of 82%, leading to annual electricity costs exceeding HK$230 million.
- Carbon Reduction Pressure: Must align with Hong Kong’s 2030 carbon neutrality goal (30% reduction in carbon emissions from public transportation).
Ⅲ. Solution: BKPOWER Industrial-Grade UPS System
3.1 Technical Architecture
| Module | Specifications and Functions |
|---|---|
| Three-Level Topology | Input power factor >0.99, THDi <2%, output waveform distortion rate <0.5% |
| Intelligent Parallel Control | Supports 8-unit parallel operation, N+1 redundancy, dynamic load balancing (±0.3% accuracy) |
| Environmental Adaptability | IP55 protection rating, supports wide-temperature operation from -25℃ to 60℃, passes IEC 61000-4-2 ESD test |
3.2 Implementation Strategy
- Power Quality Governance: Deploy DSP full-digital control modules to compensate for harmonics in real time, reducing THDi to below 1.5%.
- Modular Expansion: Adopt 12 units of 250kVA UPS in parallel (total capacity 3MW), with 50% expansion space reserved.
- Intelligent O&M: Connect to MTR’s central energy management system to enable remote monitoring of battery state of health (SOH).
Ⅳ. Project Achievements
4.1 Improved Power Supply Reliability
- Zero Downtime Record: System availability reaches 99.999%, with annual unplanned outages <5 minutes.
- Fault Response: Self-diagnosis system shortens maintenance response time by 80%, with MTTR (Mean Time To Repair) ≤15 minutes.
4.2 Energy Efficiency Optimization
- Harmonic Mitigation: THDi reduced from 8.2% to 1.5%, saving HK$18 million in annual electricity costs.
- Battery Life: Lithium iron phosphate (LFP) batteries have a cycle life of 12,000 times, reducing annual maintenance costs by 80%.
