Low Harmonic Distortion of Input Voltage and Current of a Medium Voltage Drive for Sugar Mill Plants

Abstract

The medium voltage drive (MVD) is a high voltage alternating current variable frequency device developed and designed for the sugar mill plant in Thailand. The medium voltage drive features offer excellent performance, easy and convenient operation and a wide range of applications using IGBT power devices and complete digital control. Using multipulse input rectification transformer technology efficiently lowers the content of the grid side distortion current to less than 3%. The power cell rectifier is a regular six-pulse diode bridge. However, the phase-shift transformer is designed to combine all power cell input currents into a 24-pulse grid side current. It meets the IEEE 519-1992 standard and the strict requirements of electric grids for distortion, and enhances the power factor to more than 0.96 lagging. Finally, the comparative performances between 12-pulse, 18-pulse and 24-pulse converters are presented.