Moving Window Min-Max Algorithm-Based Control of UPQC at EV Charging Station

This paper presents a moving window min-max (MWMM) algorithm-based control of a unified power quality conditioner (UPQC) located at an electric vehicle (EV) charging station. In UPQC, series and shunt compensation require computation of the peak fundamental positive sequence component (FPSC) of load voltage and fundamental active component (FAC) of load current, respectively. During abnormal grid conditions, d-q components contain ripples. Hence, FPSC and FAC estimation requires low-pass filtering. The proposed MWMM algorithm individually computes the mean value of d-q components by averaging the respective maximum and minimum values over a period equivalent to the harmonic of the lowest order. FPSC is computed as the root of the sum of squares of d-q axes load voltages computed by the MWMM algorithm. Similarly, the d-axis load current computed by the MWMM algorithm represents FAC. UPQC is controlled based on thus computed FAC and FPSC. With the proposed MWMM algorithm-based control, UPQC ensures power quality compliance at the charging station while maintaining sinusoidal supply currents at unity power factor and voltage regulation. Further, the experimental study shows that the MWMM algorithm outperforms previously reported techniques in terms of accurate steady-state and fast dynamic responses for FAC and FPSC extraction.