Assessment of Direct and Indirect Current Control Techniques Applied to Active Power Filters

Background: In this paper, an assessment of active power filter (APF) performance is presented under direct and indirect current control schemes through on-line compensation theory. Methods: Conventional Direct Current Control (DCC) measures both load current and filter current beside source and DC-link voltages, while Indirect Current Control (ICC) measures only source current beside voltage measurements. Both DCC and ICC control algorithms are implemented using 80C196KC low-cost microcontroller. Results: The performance parameters of APF are compared under two methods, and it is assigned that ICC gives a better performance with lower cost due to reduced number of sensors. The DC-link output voltage is controlled through simple PI-controller, and the PWM switching signals required by APF power circuit is obtained by hysteresis current controller. Conclusion: The comparative simulation and experimental results exhibit that performance of APF due to ICC scheme is superior than DCC one.

Performance of three-phase three-wire cascaded H-bridge multilevel inverter-based shunt active power filter

<span lang="EN-US">Multilevel inverter (MLI) becomes more significant in Active Power Filter (APF) application due to capability to its produce low harmonic output current in which at the same time improving performance of APF. Among the topologies of MLI, Cascaded H-Bridge (CHB) is the most popular topology with less power devices requirement and simple design. MLI CHB is also capable to produce possible output voltage at twice of the number of DC source which in this case of APF is the best suited topology to replace with the conventional six -step inverter. This paper presents the performance of three- phase three-wire CHB MLI used in Shunt Active Power Filter (SAPF) based on Direct Current Control (DCC) and Indirect Current Control (ICC) schemes. Both schemes are developed and verified in MATLAB/Simulink. The simulation results show that both current control algorithms are capable to mitigate load current with Total Harmonic Distortion below than the permissible value based on IEEE 519 standard.</span>