China Deploys Homegrown IGBTs on 800 kV Power Highways

A Fingernail-Sized Switch Takes On an 800 kV Power Highway

Inside the cavernous valve hall of a Chinese ultra-high-voltage converter station, engineers in white coveralls are bolting in components no larger than a human fingernail. Each one is an insulated-gate bipolar transistor, or IGBT, the power semiconductor that acts as a high-speed electrical switch for one of the most demanding jobs in the modern grid. China Media Group reported on September 6 that domestically manufactured IGBTs have now reached the performance standards required for plus-and-minus 800-kilovolt direct current (DC) transmission, and that deploying the technology on a project of this scale is a world first.

The breakthrough matters because of geography. China's richest wind and solar resources sit in the sparsely populated west, while its industrial load centers are thousands of kilometers away on the east coast. Moving that electricity without destabilizing the grid has forced engineers to rethink the valves that convert alternating current to direct current and back again.

Why 800 kV Pushes a Tiny Device to Its Limits

An IGBT works by switching on and off at high frequency, stabilizing voltage within milliseconds even when the grid is hit by a lightning strike or a sudden fluctuation in renewable output. In the past, limitations in materials and manufacturing meant such devices could only operate under relatively low current loads. An 800 kV ultra-high-voltage (UHV) DC link, by contrast, subjects every device to voltage and current stresses that can cause it to fail.

State Grid Corporation of China (SGCC), which operates the national UHV backbone, has driven the push to domesticate the highest-value components of the system. Industry analyses have long noted that European and Japanese suppliers, led by Infineon, Mitsubishi Electric and Fuji Electric, together hold the dominant share of high-voltage IGBT modules. Closing that gap at grid scale is a different and harder problem than the automotive IGBT localization China has already achieved.

From EV Drivetrains to the National Grid

China's IGBT industry first proved itself in electric vehicles. BYD Semiconductor, StarPower Semiconductor and CRRC Times Electric, the rail-equipment group whose British subsidiary Dynex builds high-voltage devices, have pushed domestic content in passenger-car power modules above half of the market by most estimates, overtaking Infineon in BYD's own supply chain.

Grid applications demand far higher voltage classes. The flagship test case is the Gansu-Zhejiang 800 kV project, the world's first full voltage-source converter (VSC) UHV transmission line, which began construction in mid-2024 and is now in its final commissioning phase. According to technical disclosures, a single converter station on the project contains about 4,800 submodules and more than 15,500 IGBT devices, with a line length exceeding 2,000 kilometers. The project is expected to deliver more than 36 billion kilowatt-hours of clean electricity to Zhejiang each year, roughly the annual demand of 10 million households.

State Grid-affiliated manufacturers have pushed the equipment envelope to match. XJ Electric, based in Xuchang, Henan, said it had developed the world's first 800 kV / 8 GW VSC converter valve and passed the 800 kV type test in January, a valve destined for the Gansu-Zhejiang line. In late December 2025, the world's first next-generation hybrid commutation converter valve, based on IGCT devices rather than IGBTs, entered commercial operation at the Lingbao back-to-back station in Henan after a 168-hour trial.

The Second Wave: Mengxi and the Sand-Gobi Wind Bases

The technology is now moving beyond a single showcase. In March 2026, Rongxin Huiko Electric (RXHK) won the converter valve package for the Mengxi-Jing-Jin-Ji 800 kV / 8 GW VSC project, a roughly 700-kilometer link from Ordos in Inner Mongolia to Cangzhou in Hebei. The project, with an investment of about 17.2 billion yuan (USD 2.4 billion), is designed to carry power from the large wind and solar bases being built in China's sand, Gobi and desert regions, and is expected to enter operation by 2027.

SGCC has now commissioned 43 UHV transmission projects, with cross-regional and cross-provincial transmission capacity exceeding 380 million kilowatts. The Shaanxi-Anhui 800 kV link, the first UHV DC project of the 15th Five-Year Plan period, was commissioned on June 30, 2026, adding 8 million kilowatts of capacity and cutting an estimated 5.5 million tonnes of coal use per year.

What the Milestone Means for Japan's Power Semiconductor Industry

For Japanese manufacturers, the development cuts close to home. Mitsubishi Electric and Fuji Electric are among the world's top suppliers of the press-pack IGBT modules used in HVDC converter valves, and grid equipment has been a profitable redoubt as Chinese suppliers have squeezed them in automotive power electronics. Fuji Electric is doubling wafer capacity at its Matsumoto fab and expanding its V-Series IGBT line for renewables and industrial drives, while Mitsubishi Electric has invested in silicon-carbide lines and a joint venture with Nidec for e-axle inverters.

There is a second, more subtle Japanese angle. Hitachi Energy, the grid division in which Japan's Hitachi holds a controlling stake, built the largest HVDC VSC transformer ever manufactured for the Gansu-Zhejiang project, a 750 MVA unit that began its journey from Ludvika, Sweden, toward Shanghai in mid-2026. The paradox is striking: a Japanese-controlled company is supplying the biggest transformer for a line whose semiconductor heart China has just localized, a reminder that supply chains in this industry are layered rather than binary.

Japan also faces its own version of the transmission problem. Renewable-rich regions such as Hokkaido and Tohoku must send power to Tokyo and the Kansai load centers, and the country's 50/60 Hz split makes interconnections more complex. Japanese utilities have studied VSC-based links for these corridors, and the cost curve China is now pushing down in UHV equipment could eventually influence procurement decisions across Asia, including in Japan's neighboring markets.

Why Localizing the Valve Matters Beyond One Component

The converter valve is often called the heart of an HVDC station. It performs the conversion between alternating and direct current, and it is the single most valuable equipment lot in any UHV project. For comparable full-VSC schemes, converter valve procurement has been reported at over 40 billion yuan across the two stations of a single line, meaning control of valve technology controls the economics of the entire UHV build-out.

Localization also has an export dimension. Chinese manufacturers have already supplied converter valves for international projects, including the Saudi Arabia Central-West 500 kV VSC scheme and a branch of the Wudongde multi-terminal UHVDC project. As domestic IGBTs close the final performance gap, Chinese contractors can offer complete UHV systems to the Belt and Road markets that are now building their own long-distance grids, competing directly with the established European and Japanese HVDC suppliers.

What to Watch For

The immediate test is the Gansu-Zhejiang line, where full-power commissioning will reveal whether domestically made IGBT valves hold up under real operating stress, including the summer peaks when Zhejiang's grid is stretched. A second milestone to track is the Mengxi-Jing-Jin-Ji project's 2027 target date, which will show whether the manufacturing ramp can keep pace with the construction pipeline.

For readers in Tokyo and across Asia, the more important signal is pricing. If China's UHV VSC costs fall the way its solar and battery costs did, long-distance renewable transmission becomes cheaper everywhere, reshaping regional power-trade projects from the ASEAN grid to possible Northeast Asian interconnectors. The semiconductor that fits on a fingernail is quietly deciding how the region moves its clean energy.

By Kenji Tanaka, Staff Writer

This article was produced with AI-assisted research and editorial support. Sources: China Media Group (CGTN), Sxcoal, Economic Daily, State Grid Corporation of China, XJ Electric, Hitachi Energy, HVDC World.