Inverter modelling techniques for protection studies

Traditional fault calculation techniques are not capable of accurately modelling the short-circuit behaviour of inverter interfaced distributed generation (IIDG). As the share of IIDG continues to rise, more accurate fault simulations are required. This paper gives an overview of fault calculation techniques described in literature. All techniques are evaluated from the viewpoint of protection studies in medium and low voltage grids with a high share of IIDG. The averaged value modelling technique is selected. The merits of this technique are illustrated in a Simulink/PLECS simulation environment, where averaged value models are compared to full time-domain switched models in terms of simulation time and accuracy.