Adjustable Speed Drives (ASD) Test Bench for Harmonic Distortion Evaluation

Adjustable speed drives (ASD) are the most common source of harmonics in power distribution systems reducing the power quality. The fewer harmonics injected the better the ASD is; this consideration could be used to choose a good ASD among several possibilities in the market. Even more, there is also an increasing need to check for compliance with IEEE 519. Because of this distortion, the electric quantities are difficult to measure. Harmonic or power quality analyzers are expensive equipments for small industries. The test bench proposed is based on a LabView data acquisition system together with a MatLab FFT program calculation. Hall effect current sensors and transformers used as voltage sensors produce the basic signals to, after conditioning, measure the harmonics at the point of common coupling (PCC). Digital signal-processing techniques produce evaluation data and graphics displayed at the front panel of a virtual instrument (VI). A commercial 1 hp ASD was tested with this VI and the results are reported within