毕业设计---零序电流接地选线原理与方法研究

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1、 摘 要 我国配网普遍采用小电流接地方式，其中，配网单相接地故障占配网故障的 80% 左右。由于单相接地故障的复杂性，在相当多的电弧接地情况下，稳态分量很小而暂 态分量成分很高，因此，可以利用零序电流中暂态分量的丰富信息来判断故障馈线。 本论文首先分析了小电流接地系统发生单相接地的情况，指出了单相接地故障的选线 难点，进而综述了当前的研究现状。之后本文深入分析了小电流接地系统发生单相接 地故障稳态过程和暂态过程，为选线方法寻找理论依据。然后，通过小电流接地模拟 电网在不同条件下发生单相接地故障时的实录波形分析与处理，得到了小电流接地系 统发生单相接地故障时暂态特征。结合单相接地故障时的暂态特征

2、，本文研究了现有 的选线方法，利用实录波形和仿真波形对选线判据进行验证，比较分析了各种选线算 法的优缺点。鉴于模拟电网的局限性，本论文采用 MATLAB7.1/Simulink6.3 软件平台 搭建具有 10kV 五出线的仿真电网进行大量的单相接地故障仿真实验。 为消除工频分量 的影响，本文对采样数据进行基于单零点非递归算法的陷波处理，提取出暂态高频信 号。最后，本论文提出基于零序暂态电流首半波比值的选线判据，并对该方法进行大 量不同条件下仿真实验，进一步验证该判据的正确性。 关键词：小电流接地选线；单相接地故障；零序电流；暂态分量；Simulink ABSTRACT In China，the

3、 indirectly earthed power system are commonly used in distribution network. And single-phase earth fault accounted for about 80% of all the failures in distribution network. Due to the complexity of single-phase earth faults and the arc to ground when faults occurs in indirectly earthed distribution

4、 system, for most cases the steady state component of fault current is small or approximates to zero and the transient component is high. Therefore, zero-sequence transient current can be used for fault feeder detection. First of all, this paper analyzes the occurrence of single-phase earth fault, p

5、ointing out the difficulties for fault feeder selection, and then an overview of current research. In order to search for the theory foundation of line selection, the author analyzes steady-state and transient process in-depth. After analyzing a lot of experimental data from the simulation of 6kV po

6、wer network, the author obtains the features of zero-sequence transient currents in faulty feeder arcing fault and healthy feeders while arcing fault occurs. On this basis, this paper study the principle of many existed methods of single-phase grounded feeder detection, and use recording waveform and simulation waveforms to verify their line section criteria, then a comparative analysis of their algorithm for feeder detection. Due to the limitation the simulation of 6kV power network, this pape