Issues with high power shunt active filters operating with distorted mains voltages. Dual inverter topology

This paper deals with issues related to a high power shunt active filter which is compensating the distorting regime and reactive power introduced by a silicon controlled rectifier. The current and voltage distortion is analyzed as a function of the system configuration and line reactors compensation. Different solutions are given for compensation and one of them is modeled and simulated in MATLAB/Simulink software environment. The proposed compensation system is composed by line reactors for the voltage notches introduced by the thyristor commutation, and a dual inverter shunt active power filter for the distortion regime and reactive power compensation. The advantages over the single inverter configuration are discussed. The most important one is that the harmonic current to be injected can be divided between the inverters, halving the power rating and lowering the high di/dt response demand of the PWM inductances. The used solver is continuous for an accurate representation of the plant but the active filter controller is acting like a digital one, being composed of MATLAB coded functions and discretized Simulink blocks at a fixed sample time, making possible the implementation in a real time hardware setup like dSPACE.