Two Layer Hierarchical Control Based on Distributed Secondary Control with the Aim of Improving Power Sharing and Voltage Regulation of Islanded DC Microgrids

Improvements in power electronic technology and devices cause DC microgrids (DC MGs) to be utilized in which the integration of DC distributed generation (DG) sources and loads into the power system is facilitated. Since the power sharing between DG sources and DC bus voltage regulation are two important control objectives in these microgrids, a two-layer hierarchical control strategy is implemented in this article to achieve these goals. The traditional drop control method is employed in the primary layer, but since it is not able to achieve these goals simultaneously, therefore, the proposed secondary control layer which is based on the proportional-integral cooperative distributed averaging (PICDA) secondary control strategy is introduced to overcome the challenges and achieve accurate voltage regulation. The proposed PICDA strategy has high flexibility due to the lack of prior knowledge of the grid topology and has a high convergence speed in reaching the control reference point. An islanded DC MG is simulated in MATLAB/Simulink software environment to verify the effectiveness of the proposed method, and the results of the proposed secondary control strategy are compared and analyzed with another distributed method under different operating scenarios, and the outperformance of the PICDA control method is confirmed.