The current differential protection of power lines is based on the RL lumped parameter line model and the principle of charge continuity. The traveling wave differential protection of power lines is based on the distributed parameter line model and the principle of traveling wave transmission invariance. This paper conducts a detailed comparative study on these two types of differential protections for application on power lines from the view of theory and simulation. The essential difference between the above two protections is that the traveling wave differential protection considers the distributed parameter characteristic and the spatial propagation characteristic of a line, whereas the current differential protection regards the line as a node and completely neglects the distributed parameter characteristic and the spatial propagation characteristic of a line. In fact, the differential current is the degradation form of the traveling wave differential current. For UHV long distance transmission lines, the traveling wave differential protection has a superior performance over the current differential protection. For HV and EHV transmission lines, there is no significant performance difference between the traveling wave differential protection and the current differential protection. The current differential protection is qualified for this kind of transmission line.%线路电流差动保护的基础是线路的RL集中参数模型和电荷连续性.行波差动保护的基础是线路的分布参数模型和行波传输不变性.针对两类差动保护在电力线路上的应用进行了详细的理论和仿真对比研究.指出二者的根本区别在于行波差动保护考虑了线路的分布参数特性和空间传播特性,而电流差动保护把线路看成节点,完全忽略了分布参数特性和空间传播特性,差动电流是行波差动电流的退化形式.对于特高压长距离输电线路,行波差动保护相比于电流差动保护有明显的性能优势.对于高压和超高压输电线路,行波差动保护和电流差动保护性能无显著差别,电流差动保护可以胜任该类线路.
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