Use of AFE Rectifier with Chopper Control for Performance Enhancement of Mine Dragline

For many decades, most of draglines in overburden removal in open pit coal mining used analog control under Ward Leonard method. The conventional analog control is therefore digitalized to improve efficiency, reduce the power consumption and provide low-maintenance operation instead of completely replacing the dragline. Even though digitally retrofitted Ward Leonard gives more efficiency compared with analog control, there is no major change in maintenance cost or breakdown cost. This paper proposes implementing the Active Front End rectifier with DC chopper control in old analog Ward Leonard control dragline in place of digitally retrofitted Ward Leonard control. The proposed control technique is analyzed as a case study for a digitally retrofitted dragline in Indian coal mine, and a comparative study is done with the proposed system in terms of technical and economic aspects.