K-rated transformers and active power filter for harmonic conditioning in industrial and commercial applications

Harmonic problems are common not only in industrial applications but in commercial buildings as well. This is primarily due to the switched mode power supply (SMPS) and variable frequency drives. A K-rated transformer is one which is used to deal with harmonic generating loads. K-rated transformers are sized appropriately to handle the additional heat produced by harmonic component. The Active Power Filter uses power electronic switching to generate harmonic currents that cancel the harmonic currents from a non-linear load. The harmonic current is considered as the reference current and switching signals for the VSI are generated. VSI will generate the required compensation current. In this paper SMPS were analyzed for harmonic analysis. Two techniques, K-rated transformer and active power filters, are considered and compared. K-Rated transformers do not mitigate the harmonics, but protect the transformers from overheating. The active filters mitigate the harmonics.