Grid Connected Photovoltaic Generation Plants. Components and Operation

Abstract

The main design objectives of photovoltaic (PV) systems have been for a long time to extract the maximum power from the PV array and to inject it into the AC grid. Therefore, the maximum power point tracking of a uniformly irradiated PV array and the maximization of the conversion efficiency have been the main design issues. But also, when the PV plant is connected to the grid, special attention has to be paid to the reliability of the system, the power quality and the implementation of protection and grid synchronization functions. Modern power plants are required to maximize their energy production requiring suitable control strategies to solve the problems related to the partial shading phenomena and different orientation of the PV modules towards the Sun. Moreover, the new policy concerning the injection of reactive power into the grid makes the development of suitable topologies and control algorithms mandatory. A general view of actual solutions for applications of the PV energy systems is presented. The paper covers some important issues such as the most reliable models used for simulation that are useful in the design of control systems, and the maximum power point tracking function, especially in distributed applications. The main topologies used in the PV power processing system and, finally, grid connection aspects are discussed, especially as far as synchronization, protections and integration are concerned.