Inner Mongolia's first wind-solar-storage micro-grid demonstration project equipped with series-parallel grid-forming energy storage devices was put into operation on September 10 in the heart of the Hulun Buir grassland, bringing stable electricity to 122 herder households.
The demonstration project has established a small-scale power system integrating wind power, solar power and energy storage, enabling electricity generation, storage and consumption to be completed locally.
The improvement is attributed to the fixed-frequency grid-forming and active-power control technologies, technological breakthroughs jointly made by State Grid Inner Mongolia Eastern Electric Power Co., Ltd. together with a research team from Tsinghua University, according to Wang Xinyu, a technician with State Grid Inner Mongolia Eastern Electric Power.
The technologies enable the energy storage converters to function as stable power sources with constant voltage and frequency, said Wang.
More importantly, the energy storage device is equipped with a "smart switch" that can automatically switch between two operating modes. When fluctuations occur in the main grid, it acts like a filter, stabilizing the voltage fluctuations before delivering electricity to individual households. If the main grid suffers a complete outage, it immediately switches to independent power supply mode, allowing the micro-grids to continue supplying for at least three days.
The switch between the two modes is completed automatically without even being noticed by the herders. The power supply always remains stable.
Kou Hanpeng, a technician with the State Grid Hulun Buir Power Supply Company, said that wind and solar power are both clean energy sources. The project is expected to reduce carbon dioxide emissions by 347 tonnes annually, helping cut electricity costs without adding any environmental burden on the grasslands.
In the future, the technology is expected to benefit more regions. Kou said that the micro-grid model featuring local power generation, smart energy storage and independent operation requires relatively modest investment and can be replicated in other regions, offering a useful reference for remote pastoral areas, forest regions and islands. (Edited by Li Xueqing with Xinhua Silk Road, lixueqing@xinhua.org)
A single purchase
