SoC based droop control for a DC microgrid with improved voltage regulation using Low Bandwidth Communication

Abstract

DC microgrids are becoming very popular these days because of their high efficiency and easy integration with renewable sources. The cost and efficiency depend on the effective usage of the components and reduction in the number of power electronic stages. Maintaining proper voltage regulation at the dc link is important to reduce the load side converter requirements. The work presented in this paper deals with the State of Charge (SoC) based droop control with improved voltage regulation on the DC line. Weighted average current based positive feedback term is employed for improving the voltage regulation. SoC based droop control ensures optimal utilization of all the energy storage elements, increasing the system reliability. Therefore, SoC terms are employed for both droop coefficient and the voltage regulation improvement part. The control favors SoC equalization that is made possible by communicating current and SoC information of all the sources in the microgrid to each individual converter controller. For evaluating the performance of the proposed control scheme, simulations were performed using MATLAB/Simulink for a system consisting of 2 sources and a load. The practical implementation of the system was performed for discharging mode of the storage units and the results are presented.