Decentralized Circulating Current Attenuation With Model Predictive Control for Distributed/Shunted Single/Three-Phase Grid-Tied Inverters

This letter proposed a decentralized control method to attenuate the circulating current among the grid-connected inverters without extra cost on the communication. Based on the combination of cascaded model predictive control (MPC) and modified $LCL$ filter topologies, the developed method can locally limit the circulating current for different types of inverters, e.g., single/three-phase grid-connection, and various applications, e.g., shunted or distributed inverters with/without common dc bus, respectively. The merits of the proposed method include the following. 1) Decentralized circulating current control without the need of a central controller or the corresponding communication to collect the sampling and calculate the common mode components for leakage current attenuation among different inverters. 2) Generalized control method that can be applied to single/three-phase inverters for both shunted and distributed inverters with/without common dc bus applications. 3) No synchronization is needed for pulsewidth modulation signals among different inverters to attenuate the circulating current. 4) Cascaded MPC without the need of individual inverter’s grid side uncertain filter parameters for the attenuation of circulating current and system parametric modeling. 5) Better transient performance with the inner loop MPC. The experimental results verified the proposed method.