The paper presents a grid current control technique on the power converter level. The submitted analysis deals with a control method of positive and negative current sequences in a grid connected converter during voltage sags. The control method should assure the proper exchange of active and reactive power without power ripple, the mitigation of harmonic distortion of grid currents, and should also enable the control of grid current peaks. A simple expression is determined that allows estimation of maximum active and reactive powers exchanged between the grid and converter without exceeding the admissible converter current. Some simulation and experimental results are reported to validate theoretically predicted performance of the control strategy.

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Shunt active power filters are nowadays used for mitigation of harmonic currents from nonlinear loads. Current and voltage harmonics have negative effects on the operation of the electric power system. Thus, a great attention is focused on harmonic generation and control. Several standards have introduced limits on current harmonics injected into the power system and on voltage harmonics at the system busbars. The paper proposes a switching strategy for a four-switch converter as used in conventional six-switch converters. The voltage source converter is controlled by a unique space-vector modulation strategy proposed. Here is presented an analytical solution for a proposed active power filter topology, simulation, and experiments results proving the proposed strategy correctness and its characteristics.

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