As solar generation increases globally, there exists a need for innovation and increased operational flexibility. In Photovoltaic Power Plants (PVPPs) and Large Scale Photovoltaic Power Plants (LS-PVPPs) the challenges increase due to the necessity to integrate them into the electrical system. To ensure the stability and reliability in the electricity supply, power systems require complex dynamic analysis. Therefore, to carry out these analysis, modelling and simulation tools are needed. This thesis focuses on the control and operation of PVPPs in OpenModelica, a free and open-source modelling and simulation environment based on Modelica language. In the later part, OpenModelica potential in large-scale power systemoriented models is investigated. These issues are addressed by a literature review concerning photovoltaic power systems and OpenModelica functionality, a theoretical analysis of a photovoltaic inverter and a LS-PVPP, and detailed simulations. The models are tested under variations in the active and reactive power requirements. The results show an optimal dynamic response and the capacity to perform independent active and reactive power controls. As an outcome, OpenModelica is a promising tool for power system modelling and simulation even though existing barriers and difficulties must be overcome.
