In order to evaluate the risk of DC system continuous commutation failure caused by cascading failure occurred in the receiving end of AC/DC hybrid power grid

we propose an establishment method of cascading failure set which may cause DC system to quit operation based on short circuit ratio rolling evaluation. The post-failure load rate of lines can be quickly calculated through line outage distribution factor

then the lines whose power flow are affected greater can be determined as the candidate failure lines. The cascading failure set can be established through rolling calculating the short circuit ratio and effective short circuit ratio after each failure. The DC system can be determined as out-of-service when the short circuit ratio and effective short circuit ratio of the post-failure AC system are below the thresholds. The simulation results calculated by PSD-BPA show that when the cascading failure established by the method proposed in this paper in Henan Power Grid and the short circuit ratio and effective short circuit ratio reduce below 2 and 1.5

continuous commutation failure occurs in the ±800 k V Hami-Zhengzhou DC transmission system

which can cause the DC transmission system to quit operation. The effectiveness of the method proposed is verified by the example.