Time-dependent power systems impedance - Interpretation and measuring problems

In the paper problems of interpretation and measurements of time-local impedance of the single phase power system loaded with switched and nonlinear loan's are discussed. Simulations and measurements are presented for active method of system identification for which narrow current spikes serve as system testing signals. Two practical realizations of harmonic generating devices (HGD) are dicussed and compared. The fact that even highly harmonics polluting user can Mot disturb too much system voltage waveforms makes time-local linens system I model useful if switched or even nonlinear loan's ai-e installed in the system. In the paper problem of linear model approximation of the real power system is considered.