Research on the security and stability of sending-side grid and its countermeasures considering ±800kV Yanmenguan-Huai'an UHVDC project

The impact of ±800 kV UHVDC power transmission project from Yanmenguan to Huai'an (Yan-Huai) on security and stability of sending-side grid is reserched from multiple perspectives. Firstly, the influence of UHVDC on Shanxi northern grid is analyzed from the two aspects of power transmission and grid transient stability characteristics. Then with regard to UHVDC block fault, the coupling relationship of transmission capacity between UHVDC and 1000 kV Jindongnan-Nanyang UHVAC demonstration project is researched, and the influence of different start-up modes near UHVAC Changzhi substation on the coupling relationship is analyzed. To ensure stable operation of UHVAC/DC, the corresponding control measures are proposed based on the coupling relationship. At last, considering the risk that voltage rise after UHVDC fault might cause cascading overvoltage tripping of wind turbines, the influence of wind turbines tripping under circumstances of different power output near UHVDC on security and stability of power grid is analyzed, and some advice about how to prevent cascading overvoltage tripping of wind farms is proposed.