Power system impedance measurement based on wavelet voltage imposed

The frequency response of a power system bus is an important parameter and is mainly used for designing harmonic filters, checking harmonic emission limits and predicting the system resonances. This paper presents a new power system impedance measurement method based on the addition of an independent voltage source of small energy and waveform like to Morlet wavelet. The new method then uses SWRDFT (Sliding Window Recursive Discrete Fourier Transform) to extract the harmonic current due the wavelet voltage injected in order to obtain the impedance of the system. The method was tested on various electrical power systems with different levels of complexity (two of them are presented in this paper) and the results are compared with the value obtained by the impedance meter tool from the Simulink ®. The achieved performance and the good agreement with a traditional frequency scan method are very encouraging.