A Improved Two-Layer Distributed Control Strategy for Energy Storage Units

The deployment of energy storage units (ESUs) aids in addressing the uncertainty associated with renewable energy generation. An existing control strategy for ESUs is the two-layer distributed control, where droop control strategy is implemented in the lower layer and a consensus strategy is adopted in the upper layer. However, the traditional droop control strategy always adopts a constant droop coefficient, which leads to the unbalanced SOCs of ESUs. The consensus strategy may cause a longer convergence time and steady-state error. This paper introduces an improved two-layer distributed control strategy. The first layer adopts an improved droop control strategy with adaptive droop coefficients, which can balance the SOCs of each ESU during both the charging and discharging processes. The second layer is based on the diffusion strategy, which employs a gradient strategy to achieve a higher convergence rate than the consensus strategy. Finally, simulations were conducted to verify the effectiveness of the proposed strategy.