| Abstract: | Parallel operation of inverter modules is the solution to increase the reliability, efficiency, and redundancy of
inverters in microgrids. Load sharing among inverters in distributed generators (DGs) is a key issue. This study
investigates the feasibility of power-sharing among parallel DGs using a dual control strategy in islanded mode
of a microgrid. PQ control and droop control techniques are established to control the microgrid operation. P-f
and Q-E droop control is used to attain real and reactive power sharing. The frequency variation caused by load
change is an issue in droop control strategy whereas the tracking error of inverter power in PQ control is also a
challenge. To address these issues, two DGs are interfaced with two parallel inverters in an islanded AC microgrid. PQ
control is investigated for controlling the output real and reactive power of the DGs by assigning their references. The
inverter under enhanced droop control implements power reallocation to restore the frequency among the distributed
generators with predefined droop characteristics. A dual control strategy is proposed for the AC microgrid under islanded
operation without communication link. Simulation studies are carried out using MATLAB/SIMULINK and the results show
the validity and effective power-sharing performance of the system while maintaining a stable operation when
the microgrid is in islanding mode. |
