The Yangyi Photovoltaic Power Generation, Storage and Charging Project locates in Dangxiong, Tibet, at an altitude of 4,800 metres. The project has been fully connected to the grid since 9 December 2017 and is by far the highest-altitude grid-connected large scale commercial energy storage project in the world. Based on the original 30MW photovoltaic power plant of the project and with reference to the grid curtailment history of the plant, a 4.5MW/20.7MWh battery energy storage system was designed and installed to store excess photovoltaic power for discharge (output) when needed by the grid, which also paves the way for the Group's exploration and future implementation of grid AGC services.
Merits and implications of the project:
It is the world's highest-altitude large-capacity commercial energy storage power station with a unique design enabling batteries to charge and discharge normally at high altitude and ultra-low temperature;
The technology is advanced and the response speed of the energy storage system is within 100 milliseconds. 18 energy storage converters are connected to the grid in parallel with stable operation, making it to be the project with the largest number of energy storage converters operating in parallel in the world. Such number is larger than the number (6 in total) of energy storage converters operating in parallel in the National 863 Program in 2016;
System efficiency at the AC side reaches 85%; and
It proves to have the characteristics of virtual power plants after the grid-connected performance test by the China Electric Power Research Institute, laying a solid foundation for large-scale energy storage power stations in the application of new energy power supply side in the future.