An Improved Decentralized Control of Cascaded Inverters With Robust Stability Against Grid-Voltage Variation
Xiaochao Hou, Kai Sun, Xin Zhang, Yao Sun, Jinghang Lu
Abstract
The existing decentralized control method for grid-connected cascaded inverters has the problem that the system stability is sensitive to grid-voltage variation. As a result, the system would lose stability when the grid-voltage amplitude is abnormal. To address this issue, this letter proposes a novel decentralized ω-sinϕ and V-P power control scheme. The robust stability condition against grid-voltage variation is proved. Moreover, the power-factor-angle consistency of inherent synchronization mechanism is clearly revealed for cascaded inverters, and the flexible grid power factor is enabled. For future practical applications, the proposed primary control of this letter explores a promising control idea for cascaded PV/storage systems. Finally, the performance of the proposed method is compared with the existing method by simulations under small and large grid disturbances.