Virtual impedance based phase locked loop for control of parallel inverters connected to islanded microgrid

摘要

This paper proposed modified phase locked loop (PLL) based inverter control scheme in is landed microgrid environment. Deviations in the synchronizing angle of the phase locked loop and the resistive nature of the lines are taken into account. The effects of the improper synchronization and the poor performance of the improved droop control scheme due to the resistive nature of the lines are studied. Virtual impedance based PLL is proposed to control parallel inverters and effectively compensate the improper power sharing. The proposed scheme improves synchronization, decoupling between the active reactive power and transient response. Unlike droop control, this scheme does not require any power calculations. Simulation is performed in MATLAB SIMULINK and compared with the conventional control to verify the effectiveness and improvement in the results. Experimental results are also presented and discussed to validate the simulation results with Power Hardware in the Loop using the setup of 5 kW and 3 kW parallel inverters. (C) 2018 Elsevier Ltd. All rights reserved.