Research on contrastive analysis of grounding device power frequency and impulse characteristic

Impulse characteristic and discharge process of grounding device of pole and tower for transmission line under the action of impulse current are subject to many factors, it is unreasonable to only use a constant as grounding impulse coefficient for power frequency and impulse ground impedance conversion. The paper makes a study of and analyzes the influence pattern of grounding body material, conductor section, layout type on power frequency and impulse impedance under the action of lightning current and power frequency and the influence pattern of current magnitude and wave head time on impulse grounding impedance. The relation expression between impulse and power frequency ground impedance is obtained based on feasibility analysis of decoupling of inductance effect and spark effect under the impulse current. It is observed from field test data analysis and verification that the spark effect and inductance effect decoupling may obtain accurate impulse ground impedance value by calculation, with fitting formula for impulse ground impedance recommended for zone with soil resistivity more than or less than100Ω·m.