Fault line identification of Single Line to Ground fault for non-effectively grounded distribution networks with double-circuit lines

Single Line to Ground (SLG) faults in non-effectively grounded networks are difficult to detect. Immune to neutral point grounding type, load conditions and system operation conditions, traveling-wave based method is an effective fault line identification method. However, due to the strong coupling between the double-circuit lines, the wavefront magnitude of them are the same, and the polarity of them are opposite. Thus, the mal-identification will be resulted under such condition. This paper analyzed the traveling wave characteristics of double-circuit lines, and proposed an improved fault line identification method based on the initial process of zero sequence currents and voltage traveling waves. Tests show that, the proposed method has high effectiveness in fault line identification of double-circuit lines in distribution networks.