小电流接地系统故障选线新方法研究

【作者】 刘娟；

【导师】 束洪春；

【作者基本信息】 昆明理工大学 ， 电力系统及其自动化， 2005， 硕士

【摘要】 我国大多数配电网均是小电流接地系统,该系统发生单相接地故障的几率最高,尽快选出故障线路,对于系统的运行具有重要意义。但由于单相接地故障产生的故障电流很小等多种原因,选线问题在国内外仍没有得到很好的解决。本文着重介绍了把衰减直流分量与无功功率互差法进行综合的选线方案。 首先,文章分析了小电流接地系统单相接地过程的暂态过程,重点分析了经消弧线圈接地方式的情况。在此理论基础上,对现有选线技术和原理进行逐一分析与研究。为了实现选线精度与可靠性,本文指出了单一选线方案都有局限性,应对各选线方法进行优势互补,形成优化的选线方案。 其次,多年来,很多选线方案不能得到很好应用的一个主要原因是不能准确定位故障时刻。本文采用了DFT递推算法,能准确确定故障时刻,解决了存在多年的难题。 再次,本文对于故障发生在相电压最大值和过零点附近进行区分,对于故障发生在相电压过零点附近的情况选用衰减直流分量选线方案;而对于故障发生在相电压最大值附近的情况,本文采用基于电流分解的自适应新方法的选线方案。经理论分析与数字仿真,可以发现本文提出的选线方案是有效、可靠的。 最后,本文讨论了选线方法对于电弧故障、在短线路上发生故障长线路的影响以及叠加噪声干扰的情况的选线结果,经数字仿真结果表明,本文的选线方法可以适应电弧接地故障,具有较强的抗干扰能力,而且对在短线路上发生故障,能消除长线路的影响,同时对采样率的要求不高,容易实现,选线效果好。更多还原

【Abstract】 Small current grounded systems are widely used in China, and the single-phase to earth faults are the most probable faults in distribution systems. It is necessary to select the fault circuit quickly for the correct running of system. But because the fault current is too little and many others rensons, this question hasn’ t been overcame in the world, this thesis presents a new adaptive method by using the decaying DC component and the method that using the summation of all curcuits’ reactive power but one is exclusive subtracts the one which is exclusive.Firstly, this thesis analyzed the fault transient course of small current grounded systems, especially when those systems with arc suppression coil. On the based of these theory, this thesis studyed and analysised the existing curcuit selecting methods. In order to bring precision of fault circuit selection into effect, this thesis point out that each fault circuit selection all has shortcomings. So we should introject the advantages of each method to optimize the fault circuit selection.Secondly, many circuit selection methods can’ t be used effective mostly for the fault time doesn’ t been located exactly. Using a recursive algorithm of DFT, this thesis can locate fault time exactly, thus solved a tickler which had existed many years .Thirdly, this thesis divided the system when the faulty voltage passes zero from those systems when the faulty voltage is maximal. For the system when faulty voltage passes zero, this thesis presents a new adaptive method by using the decaying DC component. As for the systems when the faulty voltage is maximal, we use the reactive power method for fault line select. Theory study and Lots of digital simulation results show that the proposed method is effective and reliable.Lastly, this thesis discussed the infuences of arcing grounded and disturbance, form the digital simulations, we can say that the method can be used in the arcing grounded system , and this method also can resistfairly disturbance, meanwhile, the method has a low requirement to sampling frequency but has a effective circuit selection.更多还原