Transient equivalent circuit of single-phase earth faults on isolated neutral system

A method for transient equivalent circuit establishment of single-phase earth faults on isolated neutral system is proposed in this paper. Firstly, the simplification principle was discussed. It can be described as: to ensure the power-frequency equivalent impedances equal, the first resonant frequency equal and comprehensive error of equivalent impedance in lowest frequency band minimum. Then, a transient circuit composed by equivalent resistance, inductance and capacitance, serially is established. Above all, the parameters calculation method is presented. On the other hand, a simple method is provided to meet the requirement of engineering application. Contrasts with traditional circuit, equivalent circuits established in this paper consider all modulus. So the simulation precision is higher than traditional circuits. Finally, the simulations verified these transient circuits are little impacted by fault point position and fault resistance.