The influence of the distributed trapped charge on VFTO

In this paper, the nodal admittance equation is derived for analyzing the response of the transmission line under the residual voltage due to uniformly distributed charge along the line in Laplace domain. We equivalent the trapped charge to the current sources which are located at near-end and far-end when the disconnector switching is operated. Based on the Numerical Inverse Laplace Transform method, the response of the transmission line is solved. And the simulation results are compared with the simulations in EMTP to confirm that the formulation is correct. Based on the equation presented in this paper, several simulations have been studied. We simulate the effect of trapped charge with different magnitude on VFTO, and the effect of length of line on VFTO.