Development of an analytic state-space description of power systems including thyristor controlled series compensation

The paper describes a method to create an analytic state-space description of power systems including thyristor controlled series compensated lines. It utilizes the periodicity of all state variables in steady-state operating mode. The system representation is based on four physically conceivable and periodic switching states which can be distinguished in stationary operation mode. The entire system, consisting of the surrounding three-phase network, the thyristor controlled reactor and the optionally switched compensation capacitors is represented in complex space-phasor networks for each of the possible switching states. In this way, the resulting state-space description considers the eigenvalues and switching sequence of the complete network structure. The respective linear independent circuits can be coupled into linear inhomogeneous boundary value problems for each operating mode which can be solved as a whole. Therefore the time functions of all state variables are obtained by a closed loop calculation.