一种采用浮动门槛的自适应突变量距离保护方案

A Scheme of Adaptive Fault Component Distance Protection Using Float Threshold

随着相量测量技术(PMU)的发展,获得其他母线处保护的相量成为可能,如何利用这些信息来提高保护性能是一个很有意义的课题。针对传统突变量距离保护在两侧系统电动势相位差较大时发生外部短路有可能误动的缺点,借助广域相量测量技术提供的信息,研究了一种根据系统实时参数自适应调整保护动作门槛的新算法。论文首先分析了传统解决办法的局限性,通过理论证明,确定了原有判据不发生误动的边界条件,在此基础上提出采用自适应浮动门槛的突变量距离保护判据。该判据能够可靠判别发生在本线路上的各种故障,ATP仿真结果验证了判据的有效性。另外,分析了新方案和原来方案各自的优缺点,两种方案在提高保护性能上能形成互补。最后,提出了一种综合两种方案并能进一步提高突变量距离保护可靠性的方案。

The phasor information of busbars other than the busbar linked to the relay is now available by means of phasor measurement unit（PMU）. Therefore, it is a significant issue on utilizing this type of information to improve the operating performance of protection. To overcome the problems caused by the conventional fault-component based distance relay, such as when a external earth fault occurred while the phase of both power system varied greatly, a novel implementation of fault-component based distance protection by adjusting the threshold based on the real-time parameters of the power system is put forward. The limitations of the conventional solutions are discussed at first Then, the boundary conditions of the existing criteria are determined and proved in theory. A floating threshold based novel criterion is therefore proposed to sovle this problem. It is verified with ATP simulation tests that this criterion is stable when experiencing the external faults. Meanwhile, it can discriminate the internal faults under the extreme conditions. Further, the new criterion and the existing criteria are compared with each other, and their advantages and disadvantages are highlighted. These criteria can reinforce with each other in terms of protection performance. Finally, an effective comprehensive scheme to improve the reliability of fault-component based distance relay is proposed.