Distributed Hierarchical Control of Energy Storage Systems in a DC Microgrid under Consensus Based Adaptive Droop Control Method

This paper proposes a distributed hierarchical control strategy that achieves State-Of-Charge (SOC) balancing, current sharing, and voltage restoration for Energy Storage Units (ESUs) with different capacities and SOCs. The adaptive droop control is used in the primary control level, and the droop coefficient is adjusted based on the SOCs and capacities of ESUs and the observed average SOC and capacity. A consensus algorithm is used to estimate the relevant average parameters. In the secondary control level, a proportional consensus algorithm-based control architecture is used to minimize the deviation of the DC bus voltage. The proposed control architecture guarantees the DC-bus voltage restoration even under transmission and self-processing delays. The effectiveness of the proposed distributed control strategy is evaluated in both simulations using Simulink and Hardware In the Loop (HIL) tests using the Typhoon HIL device. The experimental results showed that the control strategy achieved SOC balancing, current sharing, and voltage regulation while being robust to communication delays.