Fault response of grid-connected inverter dominated networks

The rapid increase in installed distributed generation (DG) has led to concerns about the impact on the proper operation of the protection system. In particular, the limited fault current capability of inverter interfaced distributed generation (IIDG) could lead to malfunctioning of the distribution network protection system which largely relies on overcurrent based protection techniques. The absence of tried and tested models and methods to calculate the inverter fault current contribution has been a significant challenge to the introduction of IIDG. This paper shows that with a few subtle changes, conventional analytical network analysis techniques can be used to analyse the fault response of inverter dominated distribution networks. The theoretical results are validated by PSCAD simulations and experimental results.