The study of fault location in distribution systems has being carried on for about ten years.Because of undistinguished fault features in single-phase-to-ground fault, it is being a knotty point.

• 小电流接地系统故障测距的研究历史不长，由于其单相接地故障特征不明显，一直被认为是一个难点，至今尚无成熟的应用。