On some spectrum estimation methods for analysis of non-stationary signals in power systems - Part II: Numerical applications

This is a companion paper to a paper of the same title, Part I, in which the theoretical aspects of some spectrum estimation methods for analysis of non-stationary voltages and currents in power systems with nonlinear loads are analysed. In particular, the Prony model and rootMusic method are taken into account. In this paper, numerical applications of the methods presented in Part I are discussed, in order to illustrate their implementation problems and practical applications. To investigate the methods, several experiments were performed using non-stationary voltage and current waveforms in a supply system of a dc arc furnace. For comparison, similar experiments were repeated using the Short-Time Fourier Transform. The comparison proved the effectiveness of the new methods; however, their computational efforts can be much more complex. Conclusions and recommendations are made concerning the framework of each method.