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.
KEYWORDS:
1.
Microgrid
2.
Inverter parallel
operation control strategy
3.
Droop control strategy
4.
Frequency restore
5.
Power sharing
SOFTWARE:
MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 2 Output voltage and current waveforms at PCC under the
proposed dual –control
Fig. 3 Tracking output power of PQ control inverter
CONCLUSION:
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