中文摘要：

继电保护隐藏故障是造成输电线路连锁跳闸的主要原因。通过分析继电保护装置隐藏故障的动作机理，定义了隐藏故障的风险区域，并利用保护装置隐藏故障概率和风险区域故障概率的计算，建立了输电线路连锁跳闸的概率模型。该模型计入了多条输电线路具有不同故障概率对触发继电保护装置隐藏故障的影响，可以评估继电保护系统因隐藏故障造成连锁误切线路的概率。最后，利用实际数据进行的算例分析验证了模型的合理性，计算结果对电力系统可靠性分析及连锁故障风险评估具有参考价值。

英文摘要：

Hidden failures of relay protection are the main cause of transmission lines＇ cascading trips. This paper defines the regions of vulnerability of hidden failures by analyzing the action mechanism of the hidden failures in protection equipment. A probabilistic model, for transmission lines＇cascading trips, is established by calculating the probabilities of hidden failures of protection equipments and the fault probabilities of regions of vulnerability. This mode[ considers the impact of transmission lines having different faulty probabilities on the system protection equipment. It can estimate the probability of cascading line trips caused by hidden faults in the relay protection system. The validity of the model is shown with an example. The results provide valuable information for power system reliability analysis and risk assessment.