Flux-based multivariable control of a static converter feeding a 16.7-Hz single-phase load

AC 16.7-Hz single-phase railway grids are fed amongst others via back-to-back converters from the three-phase public grid. State-of-the-art control schemes neglect the resonant circuit connected in parallel to the DC-link capacitor due to common slow power ramps. In case of dynamic load changes and short circuits in the grids this simplified control approach leads to a long and very weakly damped transient response. Thus, oversized components are required. These additional costs can be avoided by taking the resonant circuit into account. The flux-based multivariable control for the three-phase-side converter presented in this paper is based on this approach assuring both, excellent stationary and dynamic behaviour. Here this control concept is presented in detail. Simulation results outline the mentioned advantages. The used simulation concept is verified by measurement results of a load step of 90 kW in a 400-V converter.