Power electronics for photovoltaic energy system of an Oceanographic buoy

This paper reports on design of power electronics for photovoltaic (PV) energy system of an offshore remote sensing apparatus. Challenges in design of a PV energy system for a marine application are investigated and the design limitations compared to inland PV system are discussed. The designed system includes PV cells as the main source of energy, electric storage (battery), maximum power point tracking (MPPT) and protection circuitries. An MPPT algorithm based on measuring the slope of the PV power-voltage curves is presented which can be implemented with simple analog electronic circuits. The MPPT circuit uses Sepic converter as a core and it also includes a protection unit for maintaining the battery voltage in a safe range. The performance of the proposed MPPT algorithm in presence of measurement noises is verified using a circuit simulation software tool (PSCAD). Simulation results verify that the algorithm appropriately regulates the voltage of PV cells at MPP and it is robust against measurement noises for a signal-to-noise ratio above -2db.