A Cooperative Adaptive Droop Based Energy Management and Optimal Voltage Regulation Scheme for DC Microgrids

This paper presents an adaptive droop based cooperative energy management scheme for a photovoltaic (PV) battery based autonomous dc microgrid. To overcome the basic challenges in managing multiple batteries in a distributed dc network, a cooperative cyber network is employed to formulate an enhanced adaptive droop control philosophy. With PV panels operating as a constant power source at maximum power point tracking (MPPT), battery energy storage systems cooperate among themselves to balance state-of-charge (SoC) between them and undergo constant voltage (CV) charging mode when the condition arises, which is handled using the proposed adaptive droop concept. Further emphasis is given on optimal voltage regulation to induce robustness against time-delay as compared to the conventional voltage observers, which cause high observing error. Moreover, the design criteria of the proposed strategy is provided to ensure system stability under normal and time-delayed conditions. The proposed control strategy is simulated in MATLAB/SIMULINK environment to demonstrate SoC balancing, CV charging albeit various communication issues such as delay and multiple link failure. The proposed strategy is further tested on an field-programmable gate array (FPGA)-based experimental prototype to validate the effectiveness of the proposed strategy.