Modeling and Control of a Battery Connected Standalone Photovoltaic System

Nowadays, due to the decrease of conventional energy sources and growing problem of environmental pollution, renewable energy sources are playing a big role in producing electricity. For controlling the standalone PV system, its mathematical modeling is very much necessary. So the modeling of PV system and lead-acid battery by using the corresponding equivalent circuits are discussed. Three independent control loops are used to control the whole standalone system. Those are MPPT control loop for extracting maximum power from PV module, battery control loop for bidirectional power flow between battery and DC-link through bidirectional buck-boost converter and inverter control loop for maintaining stable voltage and current at local load. The stability analysis is performed by using bode plots for both the inverter control loop and buck-boost converter control loop and these control loops are stable for our tuned controller parameters. The system is simulated in MATLAB/SIMULINK and simulation results shown to fulfill the objectives of the standalone PV system. The simulation results prove the effectiveness of the proposed controllers.