The optimized power flow control system for the photovoltaic DC microgrid

Abstract

The power flow control systems play a significant role in DC microgrids with photovoltaic inputs to supply the load with continuous power. The output power of the photovoltaic modules could experience a decline due to fluctuations in solar irradiation and temperature, which necessitates the use of batteries and the utility grid to reduce the negative effects of undesirable variations. However, an efficient control strategy is necessary to ensure an uninterrupted energy supply to the load units. This paper proposes an improved control of energy flow based on a State-of-Charge battery power estimation technique using the Coulomb counting method. By accurately estimating the available power from the batteries using the State-of-Charge technique, the microgrid is able to determine to assess if it requires to switch to the grid when the power output from photovoltaic modules is insufficient to meet the load demand. The proposed method also eliminates the need for DC bus voltage level-based approaches to charge or discharge the batteries with the advantages of the significant reduction in DC bus voltage variations. The simulation results of the proposed approach show that it provides satisfactory control performance to meet the load demand.