Xuan Hoa Thi Pham
Abstract: This paper presents a power sharing control method for use between paralleled three-phase inverters in an islanded microgrid under unbalanced and non-linaer loads. 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 and voltage quality in an islanded microgrid are 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 methodis not affected by the time delay in the communication channel and local loads. The control model has been simulated in Matlab/Simulink with two or three inverters are connected in parallel. The simulation results demonstrate the accuracy of the proposed control method. Futhermore, in order to validate the theory analysis and simulation results, the experimental setup was built in laboratory and the experimental results have demonstrated the effectiveness of proposed methods.
Keywords: Droop control, power sharing, microgrid control, parallel inverter, voltage, line impedance, voltage unbalanced compensation