This paper describes the solution of power quality problems arising from 12-pulse smelter converters in ETI Aluminium Works. The design work is based on practical data collected in the field as well as on the results of detailed simulation studies obtained by EMTDC/PSCAD, SPICE and MATLAB. Main design objective is to meet both present regulations and harmonic standards by using robust, reliable and cost effective systems with a long life expectancy. The shunt-connected passive reactive power compensation system is composed of a damped 11(th) harmonic filter and a make-up filter tuned to 5(th) harmonic with optional damping resistor. Such a system exhibits nearly transient-free switching and series-resonance proof characteristics owing to damping resistors. A close correlation has been obtained between theoretical results and field data.