Smart impedance: Expanding the hybrid active series power filter concept

Hybrid active series power filters, as originally proposed in the literature, presents a way to improve the physical limitation of tuned passive filters. However, these improvements are restricted to a single filter parameter, i.e., quality factor or tuned factor. To overcome these limitations, a hybrid system composed by active impedance, capacitor bank and appropriated control strategy, called smart impedance, is proposed. The system completely eliminates the necessity of the classical passive filter tuning procedure, which requires capacitor/inductor association for each frequency. All tuning issues are performed electronically. The proposed topology is able to manipulate, at the same time, the displacement power factor, harmonic current frequency compensation (single or multiple), quality factor and tuned factor. Practical results demonstrate the smart impedance performance and its interaction with the power system under multiples harmonics frequencies along with the displacement power factor compensation. The proposed system is simpler and more efficient than those reported in the literature. The control algorithm is executed using the DSP TMS320F2812 and the inverter switching frequency is 20 kHz.