Control Power Sharing of Parallel Inverters in Microgrid with Consideration of Line Impedance Effect

Abstract

This paper presents a power sharing control method for use between paralleled three-phase inverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significant differences for inverters connected to a microgrid has been solved, the accuracy of power sharing in an islanded microgrid is improved, the voltage droop slope is tuned to compensate for the mismatch in the voltage drops across line impedances by using communication links. The method will ensure in accurate power sharing even if the communication is interrupted. If the load changes while the communication is interrupted, the accuracy of power sharing is reduced but the proposed method is better than the conventional droop control method. In addition, the accuracy of power sharing base on the proposed method is not affected by the time delay in the communication channel and local loads at the output of the inverters. The control model has been simulated in Matlab/Simulink with two or three inverters are connected in parallel. Simulation results demonstrate the accuracy of the proposed control method. Futhermore, in order to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Results obtained from the experimental setup verify the effectiveness of the proposed method.

Robust Parallel Operated Inverters in Microgrid with SRF(Synchronous Reference Frame) – PLL(Phase Locked Loop) and SRF - Virtual Impedance Compensation Loop for Proportional Load Sharing

“…In either grid connected mode or islanded mode the microgrid must be stable maintaining voltage, frequency droops, virtual impedance compensation [5] [16] [24 ]and sharing active and reactive powers proportionally keeping minimum phase angle droop [19] [23].…”