Multi-mega VAR passive filters for mining applications: Practical limitations and technical considerations

This paper analyzes and proposes technical considerations for the selection and design of passive filter schemes rated at several mega-vars to compensate reactive power and current harmonics in mining power distribution systems. The paper includes technical information and analysis required to select the most adequate passive filter topology, to select the tuning frequency for each unit, to calculate filter parameters, and to distribute reactive power between passive filters. Passive filter schemes analyzed in this paper are used to compensate mining power distribution systems, especially when high power grinding mill drives energized from 12-pulse cycloconverters are used in conjunction with several other nonlinear loads. The manuscript also analyzes technical limitations that passive filters present in the attenuation of low frequency current harmonics. Finally, two power distribution systems with different passive filters schemes are evaluated, and the limitations in the attenuation of low frequency current harmonics generated by cycloconverters are demonstrated with measured results.