Three-phase four-branch active filter for non-active power compensation under non-sinusoidal conditions

This article presents a three-phase four-branch active filter (AF) for compensating linear and nonlinear loads. This work is motivated by the necessity to reduce the line current harmonics and to correct the deteriorated power factor caused by the increase of consumer electronic equipment. The AF is designed to compensate for the "non-active" power of the load. The current compensation is based on Fryze\´s concept of nonactive current. This definition permits the power factor to become unity, even under non-sinusoidal source voltage conditions, and balances the active power per phase. The paper presents the three-phase non-active current definition and the power system compensation, as well as the details of the control design. The AF is simulated as a non-active power compensator to validate the theory. The line current spectral test shows that the AF brings the electrical power system into compliance with the IEEE standard 519-1002