As the global energy landscape shifts toward long-distance and high-capacity power transmission, ultra-high voltage direct current (UHVDC) technology has become a key driver in national and regional grid development. Among all UHVDC projects, China’s ±1100kV transmission system currently holds the record as the highest voltage cable system in the world, representing the ultimate achievement in modern power cable engineering.
What is a UHVDC Cable?
UHVDC (Ultra High Voltage Direct Current) transmission refers to systems operating at ±800kV and above. Compared to traditional AC transmission, HVDC systems offer:
- Lower power loss over long distances
- Higher efficiency
- Better suitability for renewable energy integration
The UHVDC cable, which connects converter stations, passes through cities or rivers, and integrates with underground systems, plays a critical role in these projects. These cables must withstand high electrical, thermal, and mechanical stress, demanding the most advanced insulation and manufacturing technology.
World’s Highest Voltage Cable: China’s Changji–Guquan ±1100kV Project
Project Overview
- Project Name: Changji–Guquan ±1100kV UHVDC Transmission Line
- Location: From Changji, Xinjiang to Guquan, Anhui (China)
- Transmission Distance: ~3300 km
- Voltage Level: ±1100kV — world’s highest voltage rating
- Power Capacity: 12 GW (12,000 MW)
- Commissioned: 2019
- Developer: State Grid Corporation of China
Technical Highlights
- Advanced Insulation Materials: Innovative high-strength composite insulation system ensures safe operation under ultra-high voltage.
- World Record Transmission Distance: Over 3,000 km of continuous high-voltage transmission.
- Green Energy Channel: Transmits renewable power (wind and solar) from remote western regions to the eastern industrial hubs.
Cable Usage
While most of the ±1100kV line is overhead, specialized high-voltage cables are used at converter station exits, urban underground sections, and river crossings. These UHV cables are critical for safe and stable system integration.
Highest Voltage Submarine Cable: North Sea Link ±525kV HVDC
In submarine cable applications, the North Sea Link project between Norway and the UK is one of the most advanced:
- Voltage Rating: ±525kV HVDC
- Cable Length: ~720 km
- Power Transmission Capacity: 1400 MW
- Commissioned: 2021
- Technology: XLPE-insulated HVDC submarine cable
- Purpose: Enables clean hydropower exchange between the Nordic and British grids
Cable Industry Trends: Pushing Voltage and Distance Limits
Countries like China, India, and Brazil are investing in next-generation ±800kV to ±1100kV cable projects.
Emerging innovations such as:
- Nano-modified XLPE insulation
- Dry-type DC cable terminations
- Smart joint monitoring systems
- They are making ultra-high voltage cable systems more efficient and reliable.
From transmission capacity to voltage rating, the Changji–Guquan ±1100kV UHVDC cable remains the world’s most powerful cable project. It is a testament to China’s leadership in power grid technology and offers a blueprint for global energy infrastructure development.
Looking for more details about HVDC cable standards, insulation structure, or export certifications?
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