利用电流–电压导数线性度关系的小电流接地系统接地故障选线

Grounding Fault Line Selection of Non-solidly Grounding System Based on Linearity of Current and Voltage Derivative

更好地利用故障暂态与稳态信息,可以减少小电流接地故障选线算法复杂程度,提高适应性。分析了不接地与经消弧线圈接地系统发生单相接地故障时,不同出线暂态与稳态电气量的线性度关系,发现:健全线路的零序电流与母线零序电压导数之间始终呈正比例且比例系数为正;故障线路的零序电流与母线零序电压导数呈非线性关系或者比例系数为负的正比例关系。可对零序电流采样值序列与对应的母线零序电压差分值序列进行线性拟合,根据拟合优度及曲线斜率选择故障线路。方法可同时适用于不接地系统与谐振接地系统,且对高阻接地故障仍有较高的选线准确度,与以往的选线方法相比利用了更加丰富的故障电气量,提高了选线算法的适应性与选线的可靠性。仿真验证与现场数据验证了方法的正确性。

A better use of the fault transient and the steady state information can reduce the complexity of the line selection algorithm for the non-solidly grounding faults and improve its adaptability.This paper analyzes the relationship between the transient or the steady electrical quantities of different lines when a single-phase grounding fault occurs between the ungrounded and the resonant grounding systems.It is found that there is a direct proportion between the zero-sequence current and the zero-sequence voltage derivative of the healthy line and the proportionality coefficient is always positive.And the relationship between zero-sequence current of the faulty line and the zero-sequence voltage derivative can either be non-linear or proportional and the proportionality coefficient is negative when the relationship is proportional.The sampled value sequence of zero-sequence current and voltage differential can be linearly fitted in order to select the faulty line according to the goodness of the fitting and the slope of the curve.This method can be applied to both the ungrounded and the resonant grounding systems at the same time,and it still has a high accuracy in the line selection for high impedance grounding faults.Compared with the previous line selection method,it utilizes more abundant fault electrical quantity,which improves the adaptability of line selection algorithm and the reliability of line selection.Simulation and field data verify the correctness of the method.