Comparing the harmonic characteristics of typical single-phase nonlinear loads

Harmonic distortion in electric distribution system is increasingly growing due to the widespread use of nonlinear loads. Large concentrations of these loads have the potential to raise harmonic voltages and currents in an electrical distribution system to unacceptable high levels that can adversely affect the system. Hence there is need to study the impact of nonlinear loads in the system. This paper presents a method based on bispectrum analysis to characterize typical single phase nonlinear loads by analyzing the harmonic currents produced by these loads. Measurements are conducted using a power quality monitor to record the harmonic current waveforms, individual harmonic distortion levels and total harmonic distortion. To investigate the harmonic characteristics of these loads, the fast Fourier transform technique and the advance signal processing technique such as the bispectrum analysis are used. The results of harmonic characteristics obtained from these loads are compared so as to investigate the effectiveness of the bispectrum analysis in characterizing the various nonlinear loads.