The DC Microgrid-Based SoC Adaptive Droop Control Algorithm

In the direct current (DC) microgrid, a communication-less control algorithm to keep a stable state of the isolated DC microgrid is presented in this paper. In order to get balance of the state of charge (SoC) among multiple battery energy storage systems (BESs), a control algorithm with adaptive droop coefficient is proposed. When the SoC of BESs has a deviation, the droop coefficient will change with the SoC. The DC bus voltage is kept at a stable value within a small range of deviation using the proposed adaptive control algorithm, thus improving the voltage quality. The coordinated control strategy is significant to keep the system stable and to ensure the power balance of the DC microgrid. Finally, several representative cases are discussed and verified. The simulation results show that the DC bus voltage regulation has better stability and robustness without communication and the proposed control algorithm has a desirable performance on the balance of the SoC.