摘要
本文第一部分系统地研究了振荡以及故障时测量阻抗的变化轨迹，测量阻抗对时间的变化率等问题，并对其规律进行了总结，得出一些重要结论．第二部分阐述了利用测量阻抗的变化率来区分振荡和故障，以及区分内外故障的原理，并通过实时估计系统振荡周期的措施来提高保护的灵敏度．对文中的的方法进行仿真估计，结果表明：振荡时发生的绝大多数区内故障保护均能瞬时动作．
his paper studied the trace of apparent impedance in oscillation system and fault system, and also studied the rate of apparent impedance vs. time, and then Teached some which can apart oscillation from fault, and internal fault fronl external fault by the rate of apparent impedance. It enhances the sensitivity through on--line evaluat.ion of the oscillating period. The result of simulation has shown that most of the internal faults can be opened instantaneously when system is oscillating.
