Robust Predictive Current Control for Photovoltaic Energy Storage System Based on Second-order Tracking Differentiator

Aiming at the problem of DC bus voltage fluctuation due to the change of photovoltaic (PV) output power, load mutations and nonlinear loads connection in DC microgrid system including PV power generation and energy storage, the robust predictive current control (PCC) for photovoltaic energy storage system based on second-order tracking differentiator (STD) is proposed in this paper. The traditional current loop controller based on PI is replaced by the controller based on the PCC. And the second-order tracking differentiator for the DC bus voltage control system of bidirectional DC-DC converters is designed. The second-order tracking differentiator can track the equivalent disturbance current quickly in the system without adding additional current sensors. Feed forward method based on the STD is proposed to improve the disturbance rejection capability of the system. The simulation results show that the DC bus voltage fluctuations can be suppressed effectively by using the predictive current control based on second-order tracking differentiator, and the dynamic performance and robustness of the system are improved.