对交直流混联输电系统的运行风险评估中，由于历史数据的缺失及气候等因素 对数据测量精度的影响，输电线路的强迫停运率往往具有随机模糊的特性． 文中提出了统 一的交直流系统的随机模糊不确定性模型，并将随机模糊理论运用于交直流系统的运行 风险评估中． 该模型考虑了随机和模糊的特性，然后根据运行风险评估的定义给出了随机 模糊不确定性运行风险评估指标，最后结合交直流系统的预想事故集用随机模糊模拟技 术得到系统的运行风险指标期望值． 文中还将该模型应用在改进的 IEEE-30 节点交直流 系统中，算例结果证明了该模型的可行性． 

 In the operational risk assessment of AC/DC hybrid transmission system，the failure rate of transmission line is often characteristic of being random and fuzzy because of various uncertainties due to the lack of historical data and the influence of climate and other factors on the accuracy of data measurement． In this paper，the stochastic fuzzy uncertainty model of AC/DC transmission lines is put forward and the random fuzzy theory is applied in the operational risk assessment of AC/DC transmission system． Firstly，the model takes into account the random and fuzzy characteristics． Then the operational risk assessment index based on the definition of operational risk assessment is obtained． Finally，the expected value of the operational risk index is obtained by the use of the stochastic fuzzy simulation process combining the contingency set of AC/DC system． Take IEEE-30 AC/DC hybrid system for example and the results show that the model proposed in this paper is effective．