In early autumn, on the Shaanbei Plateau, wind turbines rotate in rows on the loess plateau, and the deep blue light on the slopes shimmers in the sunlight. In the 330kV Fanghe Substation in Ansai District, Yan'an City, a row of silver white new equipment has just been installed and is entering the final commissioning before being put into operation. Here is the world's first 35kV/30MVR static full power compensator (SPG) demonstration project.

New troubles at hub stations

The Fanghe Substation was put into operation in 2019, with one end connected to the traction power supply of residents, enterprises, and the Menghua Railway in Ansai District, and the other end connected to 14 wind and solar new energy stations. The installed capacity of new energy access in the station has reached 1.122 million kilowatts. There are also three ± 800 kV high-voltage DC transmission converter stations in the surrounding areas of Shaanxi Anhui, Shaanxi Henan, and Qingdong, which are one of the core channels for the collection and transmission of green electricity in northern Shaanxi.

The more green electricity accumulates, the more troubles come along. As the scale of grid connection continues to expand, problems such as insufficient short-circuit capacity and weak transient voltage support capability in local power grids are gradually emerging. Qiao Guangyao, the R&D leader of the SPG project at China Electric Power Research Institute, gave an analogy: with too many cars, the roadbed is not solid enough, which makes it easy to shake, and the same goes for the power grid.

Top up in milliseconds

In order to enhance the support capacity of Fanghe Substation and ensure the safe transmission of new energy, State Grid Corporation of China has laid out the construction of the world's first 35 kV/30 megawatt depleted SPG demonstration project, which will start construction in April 2026.

The value of this device lies entirely in one word. It can quickly withstand power grid faults, with a short-term dynamic reactive power support capacity of up to 90 megawatt hours per 10 seconds. It has functions such as transient low voltage support, overvoltage suppression, and short-circuit current control, which can stabilize the grid during critical moments of severe voltage fluctuations, prevent large-scale disconnection of new energy units, and ensure stable transmission of green electricity.

Domestic valves break the monopoly

The core equipment of the device is all independently developed, and the insulated gate bipolar transistor (IGBT) series valve used has broken the 30-year technological monopoly of foreign countries. Compared to traditional voltage support equipment based on MMC converter valve structure, the new equipment significantly reduces power devices and DC capacitors, as well as eliminates vulnerable parts such as mechanical switches, significantly improving reliability and greatly reducing daily operation and maintenance workload. Qiao Guangyao summarized it as being able to withstand, control accurately, and hold firmly. In other words, it means transforming high-pressure and high-capacity converter valves from mountain roads into direct tunnels. This confidence comes from long-term accumulation: since 2008, the research team of China Electric Power Research Institute and State Grid Corporation of China has continuously innovated independently, which has overcome the problem of domestication of high-voltage and large capacity IGBT series converter valves.

Advancing the project is equally challenging. Yan'an Power Supply Company has established a special working team to coordinate multiple professional forces to intervene in the entire process of equipment installation and commissioning in advance. The team has organized key personnel to collaborate with the technical team of China Electric Power Research Institute to explore and break through from scratch.keywords:Engineering infrastructure

The project is expected to be completed and put into operation in mid September, with the maximum potential to increase the new energy output of the Fanghe substation by 138000 kilowatts. At that time, the station will be able to add approximately 200 million kilowatt hours of new energy to the grid annually, equivalent to the annual electricity consumption of 66000 households.Editor/Yang Meiling