Lightning transient simulation of transmission lines considering the effects of frequency dependent and impulse corona

A simulation model in ATP-EMTP is proposed for calculating lightning transient responses of transmission lines. Both frequency dependent characteristic of transmission line and impulse corona effect are considered in this model. The frequency dependent characteristic is analyzed by Marti line model and a user defined corona model is applied to simulate the effect of impulse corona. The expression of geometric capacitance is derived by means of image theory and the dynamic capacitance for line with corona is computed. The simulation results show that the effect of corona plays a more important role than that of frequency dependent characteristic on lightning overvoltage, while it is more accurate to take both the effects of frequency dependent characteristic and impulse corona. The model presented in this paper can calculate the possible overvoltages on transmission line to provide reliable guidelines for insulation coordination and lightning protection design of transmission line.