Grounding electrode line impedance supervision (ELIS) method is used to detect and deal with faults of electrode line in UHVDC project. The reliability of ELIS depends on the difference between the normal impedance and fault impedance. Presently, there is no theoretical analysis about the fault impedance of electrode line, which makes it difficult to evaluate the adaptability of ELIS. This paper studies the fault impedance characteristic under different fault conditions by means of compound mode network. The influence of fault resistance and fault distance on fault impedance is also discussed. Then the adaptability analysis of ELIS is carreid out. The analysis results indicate that the ELIS has dead zone in some special fault points.

grounding electrode line, ELIS, fault detection, impedance characteristic, UHVDC