Distributed damping reshaping control with constraints on dual stabilities for grid‐connected inverter in high penetration grid

Abstract

SummaryThe penetration level is limited by the occurrence of harmonic resonance under weakening grid. Under conventional current control, the penetrations with different power scheduling are assessed by the impedance Bode diagrams. To further suppress the current harmonics and improve the penetration with minimum cost, this paper proposes a distributed damping reshaping method by introducing the grid current feedback loop into the modulated wave of the inverter. The additional feedback loop is obtained by moving forward the feedback point of real damping link in hardware loop. Its equivalent control block has actual physical meaning, which helps to design damping coefficient. Further, instead of relying on the experience of engineer to select the damping coefficient, considering the effect of different values of damping on the inverter's performance, a damping design principle with the dual constraints on GCI's self‐stability and the global stability of the system is proposed. In detail, the range of the possible values of damping can be obtained by setting the desired system phase margin and the desired GCI's pole‐zero locations. In this range, the damping parameter, which remains the maximum ability of harmonic suppression for penetration improvement, can be determined by setting the desired damping ratio of the poles near the imaginary axis. Finally, simulations and experimental results were conducted to verify the correctness of the theoretical analysis.