Influence of harmonic and interharmonic distortion on electrical efficiency of low voltage grids

Like the title indicates, the paper approaches a few effects of harmonics, may be the most important concerns in power quality issues, affecting directly electrical efficiency. The introductory section presents briefly a few generalities related to harmonics, i.e., their sources, their methods of analysis, as well as the most important quantitative indices related to them. The second section presents a resolution of powers in non-sinusoidal and unbalanced regimes in accordance with the standard IEC 1459-2010, chiefly important in assessing separately the contributions of the standardized harmonic power components. As a representative example, the third section is devoted to the effects of harmonics affecting induction motors, one of the most type of motors in electric drives. The following experimental section presents a comparison between two case studies in which a squirrel cage induction motor is subjected to two different voltages supply, one almost sinusoidal and the second strongly distorted by interharmonics. The analysis shows a drastic decrease in the efficiency of this type of motor in the presence of interharmonics.