Fast Harmonic Rejecting Control Design to Enable Active Support of Charging Stations to Micro-Grids Under Distortion

Abstract

This paper proposes a fast harmonic rejecting control design to enable active support of electric vehicle (EV) charging stations to micro-grids under distortion. The proposed harmonic rejecting strategy is applied to control bidirectional converters and storage elements in charging stations to improve performance of charging stations under various distorted conditions. In this approach, power quality of both ac- and dc-grids is improved by actively rejecting unwanted harmonic components in voltages, currents, and powers. A fast dynamic control design can actively reject harmonic components where harmonic filters are used to eliminate unwanted components in signals. The paper shows that the proposed harmonic rejecting method can result in a simple control design in stationary frames without any phase-lock-loop ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PLL</i> ) blocks. A two-stage optimization method is introduced under the predictive control fashion, i.e., optimizing vector angle for control performance and then modulating vector magnitude by coordinating one active- and one zero-switching state. The comparative results prove that not only control performance is resilient under distorted conditions but also the power quality on both ac- and dc-grids is actively improved. Both MATLAB/Simulink and real-time experimental platforms are used to verify the efficacy of the proposed approach in terms of compensating the reactive power, rejecting the imbalance harmonic distortions, and smoothing the dc-voltage.