DQ-Voltage Droop Control and Robust Secondary Restoration With Eligibility to Operate During Communication Failure in Autonomous Microgrid

The combination of droop control and communication-based secondary control is eligible to maintain the steady voltage and frequency at the point of common coupling (PCC) together with the property of power sharing between the distributed generators. However, the performance of this combination is threatened by the slow dynamic and communication failure. In this context, an improved droop control is proposed to address the issue of slow dynamic and enhance the power-sharing accuracy in the autonomous microgrid. The droop coefficients are determined through a comprehensive analysis to assess the eigenvalues and plot the loci of the dominant poles. Robust secondary control is subsequently proposed to restore the voltage and frequency to their nominal values with a novel feature that ensures the performance continuity during the communication failure. The key idea of the proposed secondary control relies on utilizing the predictive values of the PCC voltage in the dq-rotating frame using two dynamic lookup tables during communication loss. The proposed control is evidenced by the simulation results in the MATLAB environment.