小电流选线分类
Classification of small current line selection
市场上的小电流选线按照选线方法分：暂态信号法、信号注入法、扰动法、行波法。行波技术最早应用在高压领域进行测距，由于线路长、线路单一，测距效果良好。行波法在配网进行选线，面临出线多、出线短、网架结构复杂问题，选线效果有待提高；扰动法需要跟消弧系统配合，通过改变中值电阻或调整线圈补偿度来改变零序信号大小来实现选线，对系统有冲击影响，选线效果比较可靠；信号注入法通过PT注入固定频率信号，通过检测信号流经回路来实现选线，该方法选线可靠性受PT容量影响，实施上相对复杂；暂态信号法是目前比较成熟可靠的选线方法，利用接地瞬时的暂态信号进行选线，暂态信号具有幅值大、不受消弧补偿影响的优点，选线可靠性很高。
The small current selection lines in the market are classified according to the route selection method: transient signal method, signal injection method, disturbance method and traveling wave method. Traveling wave technology is first used in high voltage field for distance measurement. Because of long circuit and single line, the ranging effect is good. Traveling wave method is used to select line in distribution network. It faces many problems, such as many lines, short lines and complex structure of network frame. The effect of line selection needs to be improved. The disturbance method needs to be matched with the arc suppression system. By changing the middle value resistance or adjusting the coil compensation degree to change the size of the zero sequence signal to achieve the line selection, it has impact on the system and the effect of the line selection is comparable. The signal injection method injects the fixed frequency signal through the PT, and realizes the line selection by detecting the signal flow through the loop. This method is affected by the PT capacity, and the implementation is relatively complex. The transient signal method is a mature and reliable method of selecting line at present, using transient transient signal to select line, transient signal has Because of its large amplitude and no influence on arc suppression compensation, the reliability of line selection is very high.