Ningdong-Shandong ±660kV DC Power Transmission Demonstration Project. It was the key power grid construction project of “west-east power transmission” of China and was the first ±660kV voltage-class DC power transmission project in the world. The project started from Ningxia Yinchuan East Converter Substation in the west and ended in Jiaozhou Qingdao of Shandong in the east. The power transmission distance was 1335km and the transmission capacity was 4000MW. It won the first prize of Excellent Power Transformation and Transmission Project Design of State Grid Corporation in 2011.