Characteristic and noncharacteristic harmonics in AC power systems operation

The characteristic and noncharacteristic harmonics generated by an industrial rectifier have been assessed. The results of the analysis showed that the rectifier is not only a source of characteristic harmonics as it is usually assumed, but that it is also capable of injecting nonharmonic frequencies into the AC system. It is concluded that past practices of harmonic mitigation techniques based solely on the presence of characteristic harmonics need to be reviewed, and appropriate changes in the approach must be made to reduce the generation and possible injection of nonharmonic frequencies into the AC system by this type of converter installation