Application of Frequency-Dependent Network Equivalents for EMTP Simulation of Transformer Inrush Current in Large Networks

In the near future, RTE will install long cable systems and power electronics converters to reinforce its grid. This situation requires RTE to perform extensive EMTP studies to analyze the interaction between the new network components and those of the existing network. To do so, large scale modeling of the network is often required for a good representation in the case of low-frequency transients. However this “detailed network modeling” can lead to several problems; the main one being lengthy computation times. This paper describes the utilization of Frequency Dependent Network Equivalents (FDNE) to represent a substantial part of the network as a way of mitigating the lengthy computation times. Comparisons are made between FDNE and a detailed network model in time domain for the energization of transformers on the French 400 kV and 225 kV network. This paper shows that large savings in CPU time is achieved with the FDNE model for transformer energization studies, without significant loss of accuracy.