The power frequency parameters and frequency characteristic parameters of the Chenjia grounding lines of Southern Hami-Zhengzhou ±800 kV Converter are measured before the grounding lines are put into operation in order to provide a basis for calculating system stability and setting relay protection. According to the operation mode of the grounding lines

conclusions are drawn as follows: 1 Considering the skin effect

the measured AC resistance value for bipolar operation is slightly larger than the DC resistance value; 2For the impedance frequency characteristic of 47.5 and 52.5 Hz

the power frequency parameters are calculated by the weighted average method

and the results are very close to the frequency of 50 Hz measured imdepance values; 3 The frequency characteristics of zero sequence resistance rises with the increase in frequency due to the skin effect; 4The zero sequence inductance decreases slightly with the increase in frequency because the conductivity of the earth increases with ascending frequency; and 5The zero sequence capacitance keeps steady with frequency

and EMTP simulation verifies the trend.