工频变化量距离继电器耐受过渡电阻性能分析

对工频变化量距离继电器的判据进行详细分析，得到继电器经过渡电阻短路时各类故障的判据，单相接地短路故障和相间直接短路判据存在差异，各种类型的三相对称故障和两相接地故障动作判据与相间直接短路判据一致。并指出:单相接地故障时过渡电阻对继电器性能影响最大，相间故障次之。定义了使继电器能正确动作的最大耐受过渡电阻为临界电阻，推导出临界电阻的计算式。给出了电流分布系数、整定因子和继电器临界电阻曲线的定义，指出:系统工况变化和故障距离将导致电流分布系数变化，从而导致临界电阻变化；负荷和两端电源幅值比对整定因子产生较大影响，减小整定因子，有利于增加继电器的临界电阻和保护范围。通过Matlab仿真验证了上述分析的正确性。

Performance analysis of enduretransition resistance of distance relay based on the power-frequency voltage and current variation

The criterion of the distance relay based on the power-frequency voltage and current variation is analyzed in detail and will get the criterion of various faults when the relay passes through transition resistance. There is difference between the single-phase-to-ground fault and the phase-phase direct short-circuit fault. The criterion of three-phase symmetrical fault and phase-phase-ground fault of various types are similar as phase-phase short-circuit fault. And it points out:transition resistance has the most important influence on relay performance when the single-phase grounding fault occurred, and second to phase-to-phase short-circuit fault. The threshold resistance is defined as the maximum tolerance transition resistance which the relay could correct operated, and the calculation formula of the threshold resistance is derived. The definition of sequence-current-distribution coefficient, adjusting-factor, threshold resistance curve are given, which points out:sequence-current-distribution coefficient will be accompanied by system-operating-status changed, fault distance changed, and the threshold resistance changed. The load and amplitude-ratio of the two ends have great influence on the adjusting factor. Reducing the adjusting factor makes for increasing the threshold resistance and the protection scope of the relay. The correctness of the above analysis is verified by Matlab simulation.