多分支输电线路故障定位方法研究

发布时间：2018-08-31 12:48

【摘要】：输电线路在电力系统中具有举足轻重的作用,同时也是故障率最高的元件之一。故障发生后,快速准确的确定故障位置,对电力系统的快速恢复供电以及安全稳定运行具有十分重要的意义。现有的输电线路故障定位方法存在种种缺陷,尤其是对于多分支输电线路,基于此,本文针对多分支输电线路做了深入研究。输电线路发生故障时,由于故障行波在传输过程中存在衰减或者畸变,导致对行波波头的检测出现一定的误差。基于此,本文给出了一种基于相位比较的多分支输电线路故障定位方法。该方法通过在分支线路模型的基础上加装多个电流测点,以减小故障区间,从而提高故障行波波头的检测精度。首先应用加Kaiser窗的快速傅里叶变换(Fast Fourier Transform,FFT)比较相应线路上测点之间的相位差,再利用非故障区间长度与两端测点检测到的故障行波时间差的比值求得波速,最后根据双端行波原理计算出故障点位置。该方法能够准确的判定出故障区间与故障相别,在克服T节点附近存在测距死区的基础上,消除了波速不确定对定位结果的影响。基于行波固有频率的故障定位方法不受行波反射波头检测和同步时钟的制约,具有较大的优势,其核心问题是进行固有频率的提取。线路发生故障时,由于故障行波在故障点以及母线端会发生不同程度的折射与反射,容易引起固有频率的混叠现象,从而造成提取到的固有频率主成分存在误差。针对以上问题,本文提出了一种基于行波固有频率主成分比较的T型输电线路故障定位方法。该方法以变分模态分解(Variational Mode Decomposition,VMD)算法为基础,克服了传统方法无法完全消除模态混叠的弊端,具有良好的模态稳定性。并通过比较对应支路上检测到的故障暂态行波的固有频率与T节点故障时行波的固有频率的大小关系确定出故障区间,大大减小了故障区间判定的复杂度。多分支输电线路由于线路结构复杂,使得对其精确的故障定位研究存在较大的困难。本文给出一种基于行波固有频率的多分支输电线路故障定位方法。将VMD算法与多信号分类(Multiple Single Classification,MUSIC)算法相结合,得到相应模态下的频谱图,通过对多分支输电线路的故障电流行波传播路径进行深入的分析,提取出固有频率的主成分,进而进行故障测距,解决了多分支线路由于结构复杂而故障定位困难的问题。
[Abstract]:Transmission line plays an important role in power system, and it is also one of the components with the highest failure rate. It is very important to locate the fault location quickly and accurately after the fault occurs, which is of great significance for the power system to restore power supply quickly and operate safely and steadily. Especially for Multi-branch transmission lines, based on this, this paper makes an in-depth study of multi-branch transmission lines. When transmission lines fail, due to the attenuation or distortion of fault traveling wave in the transmission process, the detection of traveling wave head will appear certain errors. A fault location method for branch transmission lines is presented in this paper. The fault region is reduced by adding several current measuring points on the basis of branch line model, and the detection accuracy of fault traveling wave head is improved. Then the velocity is calculated by the ratio of the length of the non-fault interval to the time difference of the fault traveling wave detected at both ends. Finally, the location of the fault point is calculated according to the principle of two-terminal traveling wave. Fault location method based on traveling wave natural frequency is not restricted by traveling wave reflection wave head detection and synchronous clock, and its core problem is to extract the natural frequency. In view of the above problems, this paper proposes a fault location method for T-type transmission lines based on traveling wave natural frequency principal component comparison. The method is based on the Variational Mode Decomposition (VMD) algorithm. By comparing the natural frequencies of the transient traveling waves detected on the corresponding branches with those of the traveling waves at T-nodes, the fault intervals are determined, which greatly reduces the complexity of fault interval determination. Because of the complex structure of transmission lines, it is difficult to locate the faults accurately. In this paper, a multi-branch transmission line fault location method based on traveling wave natural frequency is presented. Through in-depth analysis of fault current traveling wave propagation path of multi-branch transmission lines, the principal component of natural frequency is extracted, and then fault location is carried out.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM755

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