Periodic Modelling of Power Systems

This paper treats modelling of power systems with converters in alinear time-periodic framework.A power converter is a nonlinear switching device connecting an ACsystem to a DC system. The converter generates harmonics that mightcause instabilities in systems of this kind. About a nominal periodictrajectory the power converter is well described by a periodic gainmatrix, whereas the power grids often can be described by lineartime-invariant models. Put together they form a linear time-periodicmodel. It is also shown in this paper how Integral Quadratic Constraints may beused for robustness analysis. To conclude an inverter locomotive ismodeled with the described techniques.