Comparison of direct current control techniques for a three-phase shunt active power filter

This paper deals with a comparative study of the performance of three direct current control techniques applied to a three-phase shunt active power filter. The three considered techniques are: (i) direct current control (DCC) based on a PI regulator; (ii) DCC based on a sliding mode control (SMC); and (iii) DCC based on a SMC combined with a one step ahead prediction (SMC-P). These three regulators are used to calculate the estimated peak value of the line-current in the control loop. The criterion established for current controllers comparison is chosen to be the total harmonic distortion (THD) of the line-current. It is expected that the (SMC-P) technique will improve the performance, since it avoids unnecessary switching of the solid-state devices. Indeed, this technique makes switching decisions based on the average between sampled and one step ahead predicted DC voltage errors. Simulation results are presented using Power system Blockset (PSB) of Matlab.