Mathematical modeling of composite filter for power quality improvement of Electric Arc Furnace distribution network

Electrical Arc Furnace (EAF) is one of the responsible cause for deteriorating power quality in the distribution network by, introducing harmonics, propagating voltage flicker and causing unbalance in voltages and currents. This paper presents mathematical modeling of composite filter (CF) for power quality improvement of EAF distribution network. The composite filter is consisting of a shunt LC passive filter connected with a lower rated voltage source PWM converter based series active power filter (SAPF). The control strategy adopted for composite filter operation is based on simultaneous detection of source current and load voltage harmonic based on the vectorial theory dual formulation of instantaneous reactive power. A state-space averaging model of a composite filter constructed to analyze its system stability by traditional control strategy taking into account the effect of the time delay. Simulation for a typical EAF distribution network with a composite power filter has been carried out to validate the performance. Simulation results are shown in an attempt to verify the mathematical model of the filter. The simulations have been carried out in MATLAB environment using SIMULINK and power system block set toolboxes.