UHVDC Transmission Protective Blocking Action Strategy Research

Based on the ±800kV uhvdc transmission project in construction, different closure timing strategy of rectifier and inverter station polar fault and failure valve area are studied. Analyze each fault from the rectifier and inverter stations, set $\alpha$=90, phase shift and the advantages of different action strategies are considered. Meanwhile, whether it will cause DC current impulse, whether DC current over zero is caused, whether system of energy can be transferred quickly, whether can the fault area could be isolated quickly and when faults occur in the polar regions, which strategy will lead to another pole commutation failure are considered. When faults occur in the valve area, whether a strategy selected will lead to another valve group occur commutation failure, thus get more reasonable strategies of region fault and valve fault blocking. To verify the rationality and the advantages of the strategies, the RTDS simulation platform is built by the engineering debugging, and the control system is used to carry out the experiment. Experimental results show that the selection strategy has a more significant improvement relative to the previous strategies, which can prevent various conditions of commutation failure and discontinuous current, guidance of engineering protective blocking strategy for the projects which in construction or will constructed in the future is provided.