Master-Slave Control of Parallel-Operated Interfacing Inverters Based on Wireless Digital Communication

摘要

Parallel-operated inverters with common dc and ac bus can be used as interface of PV system connecting to public ac grid. This paper presents a parallel-operated gird-tied inverter system with master-slave current-sharing control based on wireless digital communication. Firstly, the proposed master-slave control scheme is introduced. Current reference of slave modules are all given by the master module through wireless digital communication. Thus the load can be evenly shared among the modules and dc link voltage can be regulated by the sole voltage controller in master module. Secondly, the influence of communication delay and zero-order-hold on the parallel-operated inverter system is analyzed. And a design criteria to reduce the influence of wireless digital communication is studied and determined. Performance of proposed control structure and design criteria are experimentally verified. With the proposed structure, the parallel inverter system is robust, the voltage regulation and load sharing are achieved, with improved modularity and operation flexibility.