ent Harmonics in Thruster AC Dr Rig Platforms

The paper investigates the ef harmonics in oil-rig's thruster drives, whi variable frequency AC induction motor driv system in the oil rig consists of two 12 pu transformers having a relative phase shift of converter and an induction motor. The exhibits clean energy characteristics accord 519.1992 with I-THD of 2.48% and harmoni 24n±1 at the busbar when both transform loaded.Due to the nonlinear nature of diode b dc link capacitors, the input line currents ar and contain significant amount of low order h overheating of the transformer. To investig harmonics on the transformer, the mathema electrical system of oil rig and thermal m windings dry transformer is developed in temperature rise in the transformer is IEEE.Std C57.12.91.2001. The test results are to increase the thermal capability of the tran is calculated and transformer is derated temperature rise decreases with the derating o and the transformer can now be loaded beyo rating upto 1.2 pu load without overheating. Index Terms—Thruster drives, 24-pulse, Har