Experimental study on frequency-dependent properties of soil electrical parameters

• The use of broadband dielectric impedance spectrometer to conduct frequency sweep measurement of soil samples at various moisture content levels with current frequency from 50 Hz to 106 Hz.
• To discusses the change rules of soil resistivity and relative dielectric constant at various moisture content levels obtained by various experiments.
• Numerical fitting of soil electrical parameters changing with frequency is adopted by using power function, and the reasons of frequency-dependent properties of soil electrical parameters are analyzed.

In the value calculation of the impulse characteristics of a grounding device, the suitability of the key parameters of the control equation, namely, soil resistivity and dielectric constant, has a considerable effect on the accuracy of the calculation results. The values of these two soil electrical parameters differ at various current frequencies. Thus, rules on the changes of soil electrical parameters with the current frequency into the ground have to be studied. Limited research has been conducted on the change in the rules of the soil electrical parameters in the lightning current band. This paper reports on the use of the broadband dielectric impedance spectrometer to conduct frequency sweep measurement of soil samples at various moisture content levels, discusses the change rules of soil resistivity and relative dielectric constant with current frequency from 50 Hz to 106 Hz, and details the conduct of rational analysis and value fitting. Results show that change is rapid when the soil resistivity and relative dielectric constant are at low frequency (below 100 kHz), and the change slows down when the frequency increases. In the low-frequency band (below 100 kHz), the soil moisture content has a significant effect on the frequency-dependent properties of the resistivity and relative dielectric constant, and the effect is minimal in the high-frequency band. The soil resistivity and relative dielectric constant as well as the current frequency meet the power function relation.