PROJECT TITLE :

An Enhanced Power Sharing Scheme for Voltage Unbalance and Harmonics Compensationin an Islanded AC Microgrid - 2016

ABSTRACT:

In this paper, an enhanced hierarchical management structure with multiple current loop damping schemes for voltage unbalance and harmonics compensation (UHC) in ac islanded microgrid is proposed to deal with unequal power sharing problems. The distributed generation (DG) is properly controlled to autonomously compensate voltage unbalance and harmonics while sharing the compensation effort for the important power, reactive power, and unbalance and harmonic powers. The proposed control system of the microgrid mainly consists of the positive sequence real and reactive power droop controllers, voltage and current controllers, the selective virtual impedance loop, the unbalance and harmonics compensators, the secondary control for voltage amplitude and frequency restoration, and the auxiliary control to attain a high-voltage quality at the purpose of common coupling. By using the proposed unbalance and harmonics compensation, the auxiliary management, and also the virtual positive/negative-sequence impedance loops at basic frequency, and therefore the virtual variable harmonic impedance loop at harmonic frequencies, an accurate power sharing is achieved. Moreover, the low bandwidth communication (LBC) technique is adopted to send the compensation command of the secondary control and auxiliary management from the microgrid management center to the native controllers of DG unit. Finally, the hardware-in-the-loop results using dSPACE 1006 platform are presented to demonstrate the effectiveness of the proposed approach.