Capt Lorio’s research included a DC microgrid set up with a PV array, step-down switching DC-DC converter, lead acid batteries as the energy storage system and load, and an Opal-RT real-time simulator for rapid control prototyping.

Photovoltaic Array Maximum Power Point Tracking Efficiency Analysis using Real-time Hardware-in-the-loop Simulation and Testing

The current United States Navy and Marine Corps’ warfighting concepts focus on distributed and decentralized operations to increase the lethality and security of the force as a whole. An amplified reliance on electrical energy to power weapon systems, command and control structures, and other materiel, in conjunction with a distributed force, escalates the logistical requirements for each operational unit. Renewable energy resources, such as solar radiation, may be a means of reducing this logistical burden; however, photovoltaic (PV) arrays must operate at their maximum power point for these systems to be a more effective renewable energy resource technology.

This thesis studies the efficiencies of the controller for a PV power conditioning system implementing the two most common maximum power point tracking (MPPT) algorithms, “Perturb and Observe” and “Incremental Conductance”. The system includes a commercial-off-the-shelf PV array; a step-down switching DC-DC converter, engineered from standard energy storage components and an Insulated Gate Bipolar Transistor IGBT; lead-acid batteries as the energy storage system and load; and an Opal-RT real-time simulator for rapid control prototyping. First, a physics-based model of the system was simulated.Then, the efficiency of the MPPT controller, defined by the ratio of power achieved and the maximum theoretical power produced by the PV array considering environmental conditions, was studied and improved through control parameter optimization. Afterwards, the control algorithms were implemented in a physical system using the real-time simulator in a hardware-in-the-loop testing configuration. Lastly, the voltage, current, and power produced by the PV array were studied, measured, and compared to the simulated results. The experimental testing confirmed that the MPPT controller performed as designed and achieved the expected efficiency for the various solar irradiances and temperatures under which it was tested.

LEARN MORE
Capt David Lorio, USMC, is a student of Electrical Engineering at the Naval Postgraduate School. Contact Dr. Giovanna Oriti at goriti@nps.edu for more information about this research.