基于Hough变换直线检测的行波波头标定

Surge Identification for Travelling Wave Based on Straight Lines Detection Via Hough Transform

第二个波头的可靠、有效检测及辨识是单端故障行波自动测距的关键。枢纽变电站母线多出线的接线形式决定了检测到的输电线路单端电流行波中故障点反射波与对侧母线反射波极性相反,以及健全线路末端反射波幅值较低,此特性为故障点反射行波波头的有效识别提供了理论基础。大量实测数据表明:于合理短窗截取故障相电流行波数据作波形图,故障行波波头具有陡斜直线特征。从数字图像处理角度提出了基于Hough直线检测的行波波头到达时刻和极性标定方法,根据幅值、斜率等特征排除对侧母线和本侧健全线路反射波的干扰,正确辨识故障点反射波,并通过多个行波波头的时间间隔和不同分辨率下初始浪涌突变斜率一致性来校检故障点反射波辨识的有效性,从而避免近区故障时因视窗选取不合理可能导致的故障点反射波辨识错误。大量现场数据表明所提方法正确、有效。

Reliable detection and identification of the second surge is the key factor of single-ended travelling fault location. The wavefront of initial current travelling wave represents line feature through analyzing massive observed field data. Multiple-line connection configuration determines the polarity differ between reflection from fault point and reflection of remote busbar, and also determines the low amplitude of disturbance caused by reflection from end of the healthy neighbouring lines, which provides convenience for correctly capturing reflection from fault point. From the perspective of digital image processing, displaying observed travelling wave data into digital waveform image, demarcation method for travelling wave based on line detection by Hough transform is proposed, which can eliminate disturbance caused by reflection of healthy neighbouring lines and remote busbar through the amplitude and slope of surges. The confidence of wavefront identification can be determined through the interval of series fault reflected surges and the consistency of the initial wavefront slopes in different scope, which avoids mistakes caused by irrational experienced scope. The proposed method is confirmed correct and effective by massive measured field travelling wave data.