基于故障分量的方向电流差动保护

针对全电流差动保护经大过渡电阻短路时灵敏性不足的缺点，提出了利用故障分量构成的方向电流差动保护新判据。该判据可以进一步提高保护对内部故障的灵敏性和对外部故障的制动作用，与其它保护判据相比其耐受过渡电阻的能力也有了显著提高。分析了其判据和动作特性，通过数字仿真证明了此新判据在500kV、300km单回输电线路末端单相接地短路能承受300Ω以上的过渡电阻。

Directional current differential protection based on fault components

To solve the problem that phase current differential protection may be less sensitive or fail to trip when short circuit happens through big transition resistance, this paper proposed a new directional current differential protection criterion using fault components. This criterion can improve the sensitivity on internal fault and enhance the restraining function for external faults. Compared with other protection criterion, it has remarkable improvement. The criterion and its operating character were analyzed in detail. Digital simulation proves that this new criterion can tolerate over 300 ohms fault resistance for single phase to ground fault at the end or 500 kV 300 km transmission line.