Modelling and Comparative Analysis of Low-Voltage Distribution Networks at Varying Levels of Approximation

This paper focuses on the modelling of low-voltage (LV) distribution networks at various levels of approximation. Based on an Australian representative LV network topology provided with only approximate sequence impedances, we construct a comprehensive unbalanced three-phase four-wire LV network model with Australian standard conductors. In addition, we adopt three widely applied approximations: (i) neutral Kronreduced model, (ii) sequence impedance model; and (iii) singlephase equivalent model. Real-life load data are utilised, and power flow analyses are carried out using the constructed Australian LV distribution network with 61 customers and three approximate models. Results show discrepancies between the original four-wire model and the approximated alternatives, in terms of bus voltage magnitudes, network losses, as well as transformer capacity utilisation levels. It is observed that simpler models exhibit greater inaccuracies. In addition, it is noted that the nontrivial neutral voltage negatively impacts the voltage performance, highlighting the importance of considering the neutral voltage shift. Through comprehensive analyses, this paper provides insight into the fidelity of various approximation levels in representing the original four-wire LV network model, as well as the risks to anticipate in the adopted assumptions. It underscores the importance of employing a detailed model that includes neutral voltage considerations, providing researchers with a clear understanding of how their modelling choices may impact the outcomes for LV distribution network studies.