Validation of the Concept for a Wideband-frequency Grid Impedance based Grid Emulator

More and more power electronics based components such as photovoltaic inverters, wind energy systems, energy storage systems or electric car chargers are integrated into modern grids. During their development, the components' behavior in a grid is validated by using grid emulators. Existing grid emulators act as an ideal voltage source or a voltage source behind a resistive-inductive impedance. But measurements reported in literature show that grid impedances of grids containing power electronics based components are much more complex than first order resistive-inductive impedances. Therefore, in this paper a novel AC and DC grid emulator concept is proposed. It enables, different from existing grid emulators, the emulation of higher order grid impedances. Requirements, which provide guidelines for the implementation of the grid emulator, are identified based on the proposed grid emulator concept. Based on those guidelines, a simulation-based single-phase grid emulator prototype, combining a real-time simulation with a power amplifier into a single device, is developed. Two PHiL interface algorithms for linking the real-time simulation and the power amplifier are compared with respect to their influence on the emulation bandwidth and stability of the grid emulator setup. Transient simulations illustrate the grid emulator's performance and verify the theoretical results, thus validating the proposed concept.