Modeling and Experimental Validation of a Single-Phase Series Active Power Filter for Harmonic Voltage Reduction

Abstract

Research advances on renewable energy systems have increased the interest in the use of isolated power supplies composed of power converters based on high-frequency transformers. Such power equipment generally presents high internal impedance, which amplifies the effects of harmonic voltages produced by nonlinear loads that draw currents with high harmonic content. Some sensitive loads, e.g., electric motors and distribution transformers, may not properly operate when supplied by extremely distorted voltages. Series active power filters (SAPFs) are suitable to mitigate this inconvenient, being capable of providing harmonic voltage compensation and minimizing the distortion of supply voltages. In this context, this work addresses the small-signal modeling, control system implementation, and experimental validation of a single-phase SAPF. The proposed approach is solely employed for harmonic voltage compensation purposes, thus allowing loads to be supplied by a nearly sinusoidal voltage. During the modeling process, the operating steps are analyzed in detail, while the presence of parasitic elements is taken into account. An equivalent circuit is also derived, which is used to provide an easy understanding of the interactions among the SAPF, load, and power supply. From this model, transfer functions can be obtained so that it is possible to design the control loops used by the SAPF. Experimental results with distinct types of loads are presented to evaluate the SAPF performance in both steady-state and transient conditions.

Keywords

• Harmonic voltage filtering
• voltage quality
• series active power filter
• small-signal modeling
• voltage-source inverter