Advanced methods for the assessment of time varying waveform distortions caused by wind turbine 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 the analysis of non-stationary waveform distortions in power systems due to Wind Turbine Systems (WTSs) are analysed. In particular, Part I dealt with sliding window (SW) DFT, some parametric methods (SW Prony and ESPRIT) and some hybrid methods (SW ESPRIT-DFT and Prony-DFT) that conjointly use DFT and parametric methods. In this paper, numerical applications of the methods presented in Part I are discussed in order to highlight the implementation problems and practical applications. Several experiments were performed using non-stationary test waveforms and voltage and current measured on actual WTSs. The comparisons were realized on the basis of result accuracy and computational efforts. Conclusions and recommendations are made concerning the framework of each method.