Analysis of Interaction Among Multiple Parallel Three-phase Grid-connected Inverters Based on RGA

As the main interface device between distributed generation and public grid, grid connected inverter is responsible for the stable operation of distributed generation system. In order to solve the problem of interaction among inverters in the parallel system of inverters, based on the double closed-loop PR control system of LCL filter, a multiple three-phase inverter grid system which is close to the reality with relatively complex control structure based on droop control is established. For the current control loop with additional active damping control in the system, a transfer function is established at αβcoordinate system. According to the principle of relative gain array, a method is proposed to analyze the interaction among multiple parallel three-phase inverters. It can quantitatively analyze the relationship between the system control parameters, operation frequency, number of parallel inverters, filter capacitor and the interaction among inverters. Finally, a grid connected model of three-phase inverter is built in MATLAB / Simulink simulation platform to verify the correctness of theoretical analysis and the effectiveness of interaction analysis method.