Improvement of low-frequency system stability in 50-Hz railway-power grids by multivariable line-converter control in a distance-variation scenario

Stability issues are a major concern in railway grids. Although these problems are most experienced in 16.7-Hz applications, low-frequency oscillations also occur in 50-Hz railway grids. In this paper, an advanced multivariable control concept is presented. Beside achieving very good dynamic behavior, the approach improves the introduced stability problem. The proper operation of the control is verified using measurement results. A time domain simulation verifies the stability problem caused by the state-of-the-art control and shows the improved performance of the multivariable control.