A Multicell Network Control and Design for Three-Phase Grid-Connected Inverter

Three-phase grid-connected inverter with the LCL filter is commonly controlled in synchronous frame in order to independently control active power and reactive power. And proportional-integral controller is usually adopted in synchronous frame to achieve zero steady error of inverter fundamental current. However, d–q axes cross-coupling issue may deteriorate the dynamic and steady-state performance. Moreover, the weak damping characteristic of the LCL filter will lead to resonance issue. Both issues are analyzed by the established complex-vector model of the inverter in this article. A novel multicell network control structure is proposed to address both coupling and resonance problems. To design all parameters of the multicell network controller, a multiple parameter design method is proposed. Moreover, this design method can adapt to weak grid well. Based on the proposed control structure and design method, d–q axes cross-coupling issue can be addressed thoroughly, and the damping performance is also improved obviously. Besides, the excellent steady-state and dynamic performances are realized simultaneously. Finally, the superior performances of the proposed control are verified by simulation and experimental results.