Theoretical and Experimental Investigation of Networked Control for Parallel Operation of Inverters

This paper presents an inverter parallel system with a corresponding networked control strategy for parallel operations. In this system, all the modules have the same circuit configuration and two control loops: the inner control loop is used for output voltage regulation, and the outer loop is used for accurate power-sharing regulation formulated by a weighted power function with networked data. The method with low-bandwidth communication is employed to achieve the superior load-sharing accuracy compared to droop-only scheme. In addition, good robustness can be obtained in the case of communication failure. A state-space model has been developed to describe the dynamics of the active and reactive power of the networked parallel-connected inverter system. We also present the methodologies of predicting stability for system with time delay and data drop-out due to the use of network-in-the-loop of this networked parallel inverter system. Experimental results are also shown to validate the effectiveness and advantages of the proposed networked parallel inverter system.