Impulse characteristics of grounding devices considering soil ionization by the p-order time domain difference method

• Establishes the transient electrical network model of grounding devices. • Proposes the p -order difference method to solve the proposed model in time domain. • Modeling soil ionization by increasing the equivalent radius of conductor segment. • Eliminates oscillations of the response voltage and improve calculation efficiency. • The calculation error is <5.14 % verified by the full-scale experiments. Knowledge of the impulse characteristics of grounding devices is important for the lightning protection of power system. In this paper, the transient model in time domain of grounding grid is established by the electrical network theory. Then, the p -order differential algorithm is applied to solve electrical network model. To consider the soil ionization phenomenon, the soil discharge equivalent model is established and solved by iterative solution algorithm. The (3∼5)-order TDDM could eliminate partial zigzag oscillations of the response voltage calculated by the 1-order TDDM and improve calculation efficiency simultaneously. Finally, the full-scale experiments of typical grounding devices are carried out which verifies that the calculation errors are <5.14 %.