Power system properties periodical time variance investigations: hardware and software tools development

Periodical time variance of power system is the observable, but no easy to investigate power system property. The theory of time varying systems allows for mathematical description of time varying structures, their modeling and analysis. There are however problems with experimental identification of such time dependent systems. Periodical time variance simplifies significantly the identification task as delivers repeated states of time varying structures -for stationary conditions the same structure reappears to the observer periodically, giving the chance to repeat identification experiments. The identification of real power systems even in LTI conditions is not easy due to noised signals and power system nonstationariness. The paper presents a method of a complex approach to investigation of power system LPTV properties and identification of the LPTV power system model. Both simulation and experiments are discussed, as the mixed simulation/experiment approach has to be used to get the knowledge on real power system LPTV behavior.