A digital controller of active power filter applied in HVDC

In this paper, a new digital control impedance with lower cost and less space strategy of an active power filter adopting an approximate inverse system control strategy is discussed. The proposed approximate inverse system control is composed of digital band-pass filters, phase shifters and amplifiers, all which can be implemented with a TMS320C32 DSP. After the comparison of the performance of IIR digital filter with FIR digital filter, the former is preferred to be adopted here. The results of both simulations based on PSCAD and experiments on a 30 kVA HVDC system validate that the digital controller can ensure the good performance of APF without the stability problem.