输电线路复合差动保护方案

结合相量差动保护和采样值差动保护的性能特点，提出了输电线路复合差动保护方案。该方案依靠采样值差动原理在1个工频周期内可靠切除大多数较严重的故障，通过相量差动保护原理对轻微内部故障作出反应，同时引入制动电流判据，在严重外部故障时自适应增加200ms延时来克服电流互感器(TA)饱和对相量差动的影响。该方案无需配置复杂的TA饱和检测元件，保护判据成熟可靠。仿真结果表明，该方案的可靠性、灵敏性以及抗TA饱和性能均优于单一原理的差动保护。

Research on Multi-Differential Protection Scheme for Transmission Line

Traditional phasor based differential protection is easily influenced by current transformer saturation and the response of conventional sampled value based differential protection to slight internal faults is not enough sensitive. To remedy these defects, a multi differential protection scheme that can bring the respective advantages of these two differential protections into full play is proposed. In the proposed scheme, the sampled value based differential protection is used to clean most comparative serious internal faults in one cycle reliably and the slight internal fault can be detected by phasor value based differential protection;at the same time, a restraint current criterion is led into the proposed protection to overcome the impact of current transformer saturation on phasor value based differential protection by means of adaptively inserting the time-delay of 200ms while serious external fault occur. As for the proposed protection scheme, its protective criteria are ripe and reliable, and it is not necessary to configure complex detecting element for current transformer saturation. Simulation results show that the reliability, sensitivity trip speed and immunity to current transformer saturation are better than those of the single principle based differential protections.