Decentralized control scheme for a photovoltaic system connected to the utility grid

This paper is focused on a decentralized non-linear control scheme applied on a photovoltaic system connected to the utility grid. This system is a cascade scheme. On the first stage, a controller is designed to regulate the voltage at the solar panel terminals (input voltage for a boost converter) such that the maximum power transfer is achieved. On the second stage, another controller is synthesized to regulate the DC-bus voltage and power factor in the grid-connected inverter. Both controllers are based on the block control linealization technique combined with the super-twistig algorithm and they are designed independently. As a result, a decentralized control system is created. In addition, an LCL-filter is designed to connect the inverter with the utility grid in order to reduce the current harmonic content. Finally, a simulation is developed, where external disturbances are introduced in the system behavior to demonstrate robustness on the decentralized controller proposed.