Last year, China’s electricity network nearly faced a major disruption when fluctuating wind power in the northwest caused instability across the grid.
To prevent similar situations in the future, Chinese engineers have now developed a 750-megavolt-ampere (MVA) smart DC transformer, the largest of its type in the world.
Designed to handle grids with heavy wind and solar power, this transformer could redefine how electricity systems worldwide manage renewable energy.
It has “set the world record for the highest capacity of a single converter transformer in the field of flexible direct current transmission,” claims a report.
Electricity grids must constantly balance supply and demand. Even small imbalances can cause frequency changes, which, if unchecked, may spread and cause widespread outages.
Moreover, renewable energy, which depends on the weather, can change output faster than traditional power plants can adjust, creating periods of instability. Last August, this problem became critical in Xinjiang, where uncoordinated wind generation caused low-frequency oscillations that threatened the broader national network.
Current transmission systems have difficulty managing these fluctuations over long distances because the flow of power cannot be controlled precisely. To solve this problem, Changzhou Xidian Transformer, part of China XD Group, developed a large-capacity flexible DC transformer.
This smart machine converts the alternating current (AC) from power plants and local grids into direct current (DC), which flows steadily in one direction. This makes long-distance transmission more efficient and allows operators to adjust power flows quickly, helping manage frequency variations like those seen last year.
The transformer’s design includes the capability to handle rapid changes in input from wind and solar sources, fibre-optic sensors to monitor internal temperatures in real time, and magnetic field management to reduce energy loss.
The development team conducted extensive testing of their machine under extreme conditions, including lightning strikes and rapid AC/DC switching. Test results confirmed the system remained stable beyond its intended design limits.
According to Chinese media reports, this innovation, “can effectively address the instability of high-proportion renewable energy generation at the sending end,” The transformer is a part of an HVDC (high-voltage direct current) system. Such systems are designed to convert AC from power plants into DC for long-distance transmission, and then back to AC at the receiving end.
As countries worldwide increase reliance on renewable energy, HVDC systems hold great significance because they lose less power over long distances and allow finer control of electricity flows.
The smart transformer will be installed as part of China’s west-to-east power transmission project, which moves electricity from renewable-rich western provinces to energy-demanding eastern regions.
Covering 2,370 kilometres (1472 miles) from Gansu to Zhejiang, it is expected to deliver more than 36 billion kilowatt-hours per year. It is described as the first ultra-high-voltage flexible DC transmission system combining long distance, high capacity, and real-time control.
This record-breaking transformer points toward the future of grid engineering. Looking ahead, researchers are exploring multi-terminal DC networks, which could dynamically route electricity across multiple regions, making renewable energy more reliable and predictable at large scales.
