| For a proper operation of the shunt active power filters, the current reference detection method must be robust. This means it must extract correctly the fundamental frequency even if the grid has distorted and unbalanced voltages at the point of common connection. The most used reference current detection methods for shunt active power filters are analyzed and compared in this article, theoretically and through simulations in MATLAB/Simulink. One used criteria like settling time, transient performance, THD of reference and compensated grid current, overshoot and unbalance. Some practical aspects of hardware implementation and shunt active power filter design considerations are also discussed. Measured data, acquired with a dedicated data acquisition system provides the parameters required for a non-ideal real system simulation, namely a static excitation system of a power generator group. The simulated system consists of a transformer which feeds a Silicon Controlled Rectifier bridge. The Matlab/Simulink models allows for testing of the reference current detection methods implementation and improvement for dealing with problems arising with distortion and unbalance of mains voltages. Because the active power filter is a complex system, the reference current detection methods are studied with their dependencies, for example the different strategy to deal with voltage distortion and unbalance. The current controller and hardware setup are preserved. The study contributes to the existing comparisons in specialized literature by testing their weaknesses in distorted and unbalanced PCC voltages and may be useful in future hardware implementation. |
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