A Robust Adjustable Speed Drive to Operate in Polluted Grid Conditions With Improved Line Current Harmonics

With an increase in the abnormalities in the supply voltage, it is required that the Adjustable Speed Drive (ASD) connected to the grid be immune to those disturbances. Based on the field Power Quality (PQ) data study, distortion in the supply voltage is found to be the dominant disturbance followed by unbalance. It is found that these disturbances mainly affect the lifetime of dc bus capacitor and in critical cases, it may lead to a failure. In order to save the ASD from such grid disturbances, a compensation module is introduced in this article. While reducing the stress on the capacitor, this module also mitigates the harmonics in the source current of ASD. The proposed module can be a retrofit to the existing commercial ASD and can be used where the supply voltage quality is poor. The proposed topology is analyzed by simulations and validated by the test setup created in the lab.