Modelling and control of photovoltaic inverter systems with respect to German grid code requirements

The increasing share of renewable energies leads to the point where system operators require accurate modelling of generation units for planning extensions in their power system. Consequently manufacturers of renewable energy sources like wind power, photovoltaic or biomass are obliged to prove the electrical properties of their units in field test as well as validate the performance of simulation models based on the measurements. In Germany standards and technical guidelines were defined which describe the procedure for the testing of the generation units and the validation of the simulation models. Independent certification bodies have to supervise the testing and analyze the performance of the models to determine whether or not the generation unit fulfills the German Grid Code Requirement. In this paper the authors describe the different requirements of the German grid code with focus on the dynamic requirements. Additionally the testing setup and the methodology for comparing measurements with simulation are explained. Furthermore the control of a three-phase inverter system for photovoltaic application is derived. Finally simulation results of a photovoltaic inverter system are presented in order to demonstrate the behavior during short term grid disturbances.