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Investigation and mitigation of temporary overvoltage caused by harmonic filters in an oil refinery

Harmonic distortion caused by non-linear loads pose a threat to power quality that may result in failures or damage to various components of the electrical system. In this work the harmonic distortion in an oil refinery is investigated using the ATP/EMTP software. Harmonic filters are used to reduce harmonic distortion by diverting harmonic currents in low impedance paths. The switching activities of the harmonic filter may cause overvoltage to occur in the refinery causing adverse effects to the electrical system. This paper presents an investigation of the temporary overvoltage caused by the energizing and de-energizing of the filter with the aim to determine whether they exceed the withstand limits of the system. Thus, mitigation measures would be needed if the overvoltage is greater than the power frequency withstand level. For this reason, the use of pre-insertion resistors, surge arresters and controlled switching is considered to ascertain the effectiveness these components would have on mitigating the overvoltage.