中文摘要：

应用概率方法研究保护动作判据的性能，提出了保护判据的可靠性评估模型。首先描述了几种比率差动保护判据的制动特性和灵敏度要求，及其在差动量和制动量关系平面上保护启动概率的分布情况；然后以实际运行方式下制动量和差动量变化范围内启动概率的平均值作为基础可靠性参数，推导出保护动作判据的拒动概率和误动概率。最后用算例说明了所提方法的实用性和有效性。

英文摘要：

By means of probabilistic methods the performance of protection action criteria is researched. On this basis the authors propose an operational reliability evaluation model for protection criteria. Firstly, the authors describe the restraint characteristics of several percentage differential protection criteria and the requirements to sensitivity, and distribution of protection action probability on the differentia quantity and restraint quantity relationship plane; then taking the mean value of action probability within the varying range of differentia quantity and restraint quantity under actual operating mode as the basic reliability parameters, the misoperation reliability and maloperation reliability of protection criteria are deduced; finally, the practicality and effectiveness of the proposed model are illustrated by calculation examples.