Power quality enhancement for charging station with moving window min-max algorithm based shunt active power filter

The widespread development of charging infrastructure is essential for the projected growth of electric vehicles. These charging stations are non-linear loads and necessitate shunt active power filters (SAPFs) to prevent the propagation of current distortions into the grid. Otherwise, the system efficiency and power transfer capability would reduce. This paper proposes control of SAPF with a moving window min-max (MWM) algorithm-based computation of the fundamental active component (FAC) of load current. The proposed algorithm computes FAC as the average of the maximum and minimum value of d-axis current over the period corresponding to its lowest order harmonic. The lowest harmonic is six and two for the balanced and unbalanced loading, respectively. Based on whether the currents are balanced or not, the MWM algorithm determines the width of the moving window where the minimum and maximum values are stored for computing FAC. The computational simplicity of this algorithm is evident from the pseudo-code presented. The experimental results show that the proposed method offers faster dynamic and accurate steady-state responses than the low pass filter-based synchronous reference frame method. Furthermore, analysis of SAPF operation with the proposed extraction scheme based on simulations reveals that the charging station operation complies with the power quality standards. (C) 2022 The Author(s). Published by Elsevier Ltd.