A new fault location method based on approximate entropy for the transient zero-mode power was proposed. In this method, the approximate entropy value of every detection point for transient zero-mode power was calculated first. The scale factor value of approximate entropy for rach section was then calculated and compared to the threshold which preset in control main station. If the scale factor value is greater than the threshold, the section is determined as healthy, otherwise faulty. A large number of ATP simulation shows that fault in both ungrounded system and grounded system with are suppression coil can be located effectively with random initial phase and transition resistance. The method has good performance even with grounding impedance as high as 5 000 ohms. According to the ratio curve of scale factor versus margin sellings, the optimal working range for each initial phase was also defined.%提出了一种基于暂态零模功率近似熵的故障区段定位方法.该方法在计算出各检测点暂态零模功率近似熵值的基础上,通过求取近似熵比例因子数值与控制主站中事先设置的阈值进行比较,若该因子值大于阈值,则判定为健全区段;若小于阈值,则判定为故障区段.大量的ATP仿真实验表明,无论是中性点不接地系统还是经消弧线圈接地系统.对于任意初相角和过渡电阻值时,该方法均能有效判定出故障位置,并且在5000Ω高阻接地故障时,仍然有良好的表现.通过比例因子之比曲线衡量阈值设定时裕度的大小,最终确定该故障定位方法在各初相角条件下的最佳性能工作区间.
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