Case Study: Hitachi Energy Ltd. – Empowering China’s Ultra-High-Voltage Grid with Advanced Gas-Insulated Substation Technology
Headquarters: Zurich, Switzerland
Offering: 1,100 kV Gas-Insulated Switchgear (GIS) and Digital Substation Solutions
Introduction
Hitachi Energy Ltd., a global leader in power systems and energy infrastructure, continues to play a pivotal role in shaping the modern electrical grid landscape. As nations transition toward smarter, more resilient, and sustainable power transmission networks, Hitachi Energy’s gas-insulated substation (GIS) technologies have become instrumental in enabling efficiency and reliability across complex grid infrastructures.
In 2025, the company achieved a significant milestone by deploying 1,100 kV GIS systems for the Nanchang Ultra-High-Voltage (UHV) substation in Jiangxi Province, China. This project formed a key component of China’s nationwide UHV grid development program — a strategic initiative designed to interconnect regional power networks, stabilize load demand, and improve renewable energy integration capabilities.
Background and Project Context
China’s rapid industrial growth and increasing urbanization have driven an urgent need for reliable, high-capacity transmission infrastructure. Traditional air-insulated substations (AIS) are often challenged by land constraints, environmental factors, and safety limitations — especially in urban and high-voltage applications.
To address these challenges, the State Grid Corporation of China (SGCC) initiated a modernization plan to expand its UHV transmission corridor, connecting provinces such as Hunan and Jiangxi. The objective was clear: improve cross-provincial power exchange capacity while ensuring minimal transmission losses and robust grid stability.
Recognizing the technical complexity and voltage requirements, Hitachi Energy was selected to deliver the 1,100 kV GIS for the Nanchang UHV substation. This project became a showcase of how advanced insulation, compact designs, and digital control systems can collectively revolutionize high-voltage power infrastructure.
Case Study: Implementation of 1,100 kV GIS in Nanchang UHV Substation
The Nanchang UHV substation represented one of China’s most ambitious grid modernization projects, aiming to strengthen the transmission backbone connecting central and southern China. Hitachi Energy’s role was to provide cutting-edge GIS technology capable of handling ultra-high voltage levels with exceptional reliability, safety, and environmental performance.
The company designed and delivered a suite of GIS modules featuring compact metal-enclosed switchgear, optimized for both space efficiency and operational resilience. The GIS system’s modular structure allowed for seamless integration with digital substation automation systems, enabling real-time data analytics, predictive maintenance, and improved fault detection.
The installation utilized hybrid insulation architecture, combining SF₆ gas with advanced sealing mechanisms to minimize leakages and reduce environmental impact. Additionally, the GIS units were equipped with AI-based diagnostic tools to continuously monitor gas density, temperature, and pressure, ensuring early anomaly detection and proactive maintenance scheduling.
One of the defining features of this deployment was its digital control layer, enabling remote operation and predictive maintenance capabilities. Through this, operators could monitor circuit breaker conditions, insulation integrity, and partial discharge activity — thereby reducing unplanned outages and extending equipment lifespan.
Outcome and Measurable Impact
The project yielded substantial operational and environmental benefits, reinforcing the long-term value of GIS technology in high-voltage grid systems.
Improved Transmission Efficiency:
The new GIS system achieved a 15% improvement in electricity transmission efficiency compared to legacy AIS-based systems. This gain was primarily due to reduced dielectric losses and optimized conductor performance within a fully enclosed, controlled environment.
Land Use Optimization:
Due to its compact modular design, the Hitachi GIS solution reduced land usage by approximately 60% compared to conventional substations. This was a critical advantage in densely populated or geographically constrained regions like Nanchang.
Enhanced Grid Reliability:
The UHV substation demonstrated significantly improved voltage stability and reliability, particularly during peak load conditions. The GIS configuration allowed for better fault isolation, shorter recovery times, and improved resilience against environmental disruptions such as humidity and dust.
Operational Efficiency:
Integration with digital monitoring systems enabled continuous equipment performance tracking, allowing maintenance teams to act based on real-time data insights rather than fixed schedules — effectively reducing maintenance costs and downtime.
Protectional and Safety Measures
Given the extreme voltage levels, the Nanchang project required stringent protection measures to ensure safety and environmental compliance. Hitachi Energy implemented multi-layered protectional systems, including:
-
SF₆ Gas Monitoring and Containment:
Real-time sensors tracked gas pressure and density to prevent leakage. The system adhered to IEC 62271 safety standards and incorporated zero-leak sealing technology, ensuring emissions stayed well below the permissible limit of 0.1% per year. -
Advanced Insulation Materials:
The GIS utilized next-generation fluorinated gas mixtures with lower Global Warming Potential (GWP) while maintaining insulation strength. -
Arc-Resistant Design:
The substation included arc-resistant metal enclosures and pressure relief vents to protect both personnel and equipment in case of internal arcing. -
Digital Safety Interlocks:
Embedded sensors and interlock mechanisms prevented human access to high-voltage compartments during operation, ensuring maximum operator safety.
These protectional measures positioned the project as a benchmark for safety, efficiency, and environmental responsibility in ultra-high-voltage infrastructure.
Impact on the Market
The success of this project significantly enhanced Hitachi Energy’s reputation as a leader in UHV GIS technologies. By demonstrating measurable performance gains and environmental advantages, the company reinforced its position as a trusted partner in Asia-Pacific’s ongoing energy transformation.
The project also marked a shift in how utilities approach high-voltage transmission planning — prioritizing compact, digital, and eco-efficient solutions over traditional substation designs. It inspired similar deployments across regions like India, Indonesia, and the Middle East, where urbanization and renewable integration demands continue to rise.
Furthermore, the deployment of 1,100 kV GIS systems helped accelerate the adoption of smart grid and AI-driven maintenance frameworks, underscoring the strategic importance of digital substations in achieving operational sustainability and grid resilience.
Financial Impact After Implementation
From a financial perspective, the Nanchang GIS project contributed to a 9% year-on-year increase in Hitachi Energy’s Transmission Solutions segment revenue in 2025. The project’s success led to multiple follow-up contracts across Asia-Pacific, including agreements with State Grid Corporation of China and Power Grid Corporation of India (PGCIL) for high-voltage GIS deployment.
The return on investment extended beyond direct revenue growth. The project also generated long-term service and maintenance contracts, ensuring recurring income and strengthening the company’s ecosystem presence in high-voltage grid solutions.
By achieving a blend of operational excellence, sustainability, and digital integration, Hitachi Energy set a new industry benchmark for high-voltage GIS installations one that continues to guide the global power transmission market’s evolution.
Conclusion
The Hitachi Energy – Nanchang UHV Substation case study exemplifies the transformative power of innovation in the Gas-Insulated Substation (GIS) Market. It showcases how advanced engineering, digital intelligence, and sustainable design can converge to deliver tangible outcomes — from efficiency gains and environmental protection to market leadership and financial growth.
In a world where grid reliability and sustainability are increasingly non-negotiable, Hitachi Energy’s 1,100 kV GIS deployment stands as a symbol of the next generation of smart power infrastructure — compact, connected, and climate-conscious.
Dive into the full analysis here: https://www.precedenceresearch.com/gas-insulated-substation-market
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