|In power system engineering, a digital twin is a virtual representation of the grid that allows to understand and predict its behavior. However, due to the sensitive and condidential information the use of digital twins is limited to transmission system operators and utilities. As a consequence, the design, test and validation of any proposed implementation by the research community or the industry is limited to existing benchmark models. Nevertheless, most of these test bed systems lack the complexity or size of modern power grids. Alternatively, it is possible to create synthetic networks that have a similar topology and characteristics of a grid based on publicly available data. Several existing synthetic networks are based on meshed power systems and are available for phasor simulations or energy economic studies. This work aims to expand the research related on synthetic networks by deriving and developing one based on the Australian National Electricity Market (NEM), a longitudinal power system. The model, being jointly developed with OPAL-RT's AXES and eDBsim teams, will allow real-time electromagnetic transients simulations in OPAL-RT's HYPERSIM.