Statistical Study of Personal Computer Cluster Harmonic Currents from Experimental Measurements

The net harmonic currents generated by a cluster of desktop personal computers are studied statistically. Personal computers (PCs) are single-phase non-linear loads with low individual consumption but significant collective distortion effects, as many of them can be connected to the same bus (personal computer cluster). This article reports experimental measurements of harmonic currents injected by single-phase rectifiers and seven personal computer types during four operating modes. The probability density functions (pdfs) of the harmonic currents (magnitude and phase angle) are investigated from the measurements. An analytical procedure to obtain these probability density functions for any typical personal computer working session is described and experimentally validated. The obtained probability density functions are found to be applicable to large-scale harmonic penetration statistical studies. Furthermore, attenuation and diversity effects are analyzed from the previous probability density functions, and the harmonic current cancellation effect on personal computer clusters is investigated with Monte Carlo simulations.