Energy coordinated control of DC microgrid integrated incorporating PV, energy storage and EV charging

Abstract

The power of photovoltaic (PV) and electric vehicles (EV) charging in integrated standalone DC microgrids is uncertain. If no suitable control strategy is adopted, the power variation will significantly fluctuate in DC bus voltage and reduce the system’s stability. This paper investigates the energy coordination control strategy for the standalone DC microgrid integrated with PV, energy storage, and EV charging. The specific research contents include the following: The maximum power point tracking (MPPT) control of the variable-step perturbation observation method is proposed to shorten the regulation time of the PV unit to reach the maximum power point; an improved droop control is designed based on the state of charge (SOC) of the batteries, and the power equalization and bus voltage recovery secondary controls are introduced to enhance the regulation effect of the DC bus voltage; a coordination control strategy based on the power difference is formulated to improve further the transient and steady-state performance of the DC bus voltage. The proposed coordination control strategy is applied to the integrated standalone DC microgrid model built by MATLAB/Simulink. The simulation results show that the proposed coordination control strategy can not only effectively improve the stability of the DC microgrid system but also reduce the capacity redundancy of the energy storage device.