The first domestically developed DC support capacitor, led by the State Grid Economic Research Institute, has completed third-party type tests. Its core performance indicators, such as long-term lifespan, loss, and temperature rise, have reached international standards. It has also been applied in batches for the first time in the Gansu–Zhejiang ±800 kV ultra-high voltage direct current (UHVDC) transmission project. This capacitor, known as the "voltage-stabilizing heart" of flexible DC converter valves, was previously reliant on imports. The research team not only formulated specifications containing 135 technical indicators, overcoming bottlenecks in mass production and material selection, but also innovatively developed an online monitoring system based on high-potential integrated sensors. Ultimately, the product cost was reduced by over 20% compared to imported alternatives, advancing the autonomous and controllable supply chain for China's core flexible DC transmission equipment.

Key Information Interpretation
Breakthrough Product: DC Support Capacitor
Functional Role: Referred to as the "voltage-stabilizing heart" of flexible DC converter valves. It plays a critical role in energy storage, voltage stabilization, and harmonic absorption within the converter valve, making it a core component for ensuring the safe and stable operation of UHVDC transmission systems.
Previous Status: Long-term reliance on imports, representing a "chokepoint" in China's industrial and supply chains.
Significance: Achieving "Autonomous and Controllable" Status
Technological Independence: Mastered the full suite of technologies, from material selection and technical specifications to mass production, and established stringent specifications containing 135 technical indicators.
Supply Chain Security: Freed China's flexible DC transmission core equipment supply chain from external dependencies, safeguarding national energy strategic security and the initiative in grid construction.
Cost Reduction: After localization, the product cost was reduced by over 20% compared to imported alternatives, delivering significant economic benefits.
Technical Level: Reaching International Standards
Passed rigorous third-party type tests, demonstrating that its core performance indicators, such as long-term lifespan, loss, and temperature rise, have reached the level of international counterparts, meeting the demanding requirements of engineering applications.
Innovation Highlight: Integrated Intelligent Monitoring
Developed an online monitoring system based on high-potential integrated sensors. This enables real-time, remote monitoring of capacitor conditions during operation, allowing for early warnings of potential failures and significantly improving system maintenance and reliability.
Engineering Application: Successful Implementation
Achieved batch application in the Gansu–Zhejiang ±800 kV UHVDC transmission project, proving its technical maturity and engineering applicability.

Summary
The successful development and application of the first domestically produced DC support capacitor represent a major achievement for China in the field of high-end power equipment manufacturing. It is not merely a substitution of a single product but a comprehensive breakthrough encompassing technology R&D, standard formulation, material processes, and intelligent monitoring. This advancement strongly promotes the upgrading and localization of China's entire UHVDC transmission technology industrial chain, laying a solid foundation for the construction of more advanced flexible DC transmission projects in the future.