Comparison of 50-Hz railway line-side converter input-admittance for different substation distances and control concepts

Stability problems are a major issue in railway grids for both, 16.7 Hz and 50 Hz applications. Thus, the impact of the traction vehicle line-side converter control has to be evaluated. One method to obatin informations about the system is to measure the input-impedance of the traction vehicle. In this paper, the input impedance of traction vehicles with two different line-side converter controls is computed at different distances to the substation. On the one hand the conventional PI control is determined, on the other hand the admittance representation of an advanced multivariable control is given. Both impedances are calculated at two different distances, showing the influence of different control structures on the resulting impedance.