Effect of Jiuhu UHVDC System Fault on Sending Wind Turbines

Abstract

The corresponding control strategy is proposed which can restrain the transient overvoltage in a certain extent, even the large-scale wind turbine separated from the power grid when the fault of DC commutation failures and DC system blocked takes place frequently in UHVDC transmission system from Jiuquan to Hunan. Firstly the basic situation of UHVDC transmission and characteristics of the wind generator are introduced. Secondly influencing factors of transient overvoltage are analyzed and the risk of wind power off-grid caused by overvoltage is expounded from the occurrence mechanism of commutation failure and blocking fault. Then, both are verified by case study and simulation analysis. At last, the thesis puts forward some effective strategies to prevent the wind power off-grid accidents from the installation of the dynamic reactive compensation device, the improvement of the short circuit capacity, the strengthening of the grid structure, and the improvement of the wind power capacity.