Generalised transformer modelling for power flow calculation in multi‐phase unbalanced networks

Abstract

Low voltage systems are unbalanced networks where a significant share of the users is single‐phase connected, so a multi‐phase system needs to be considered in order to assess the mutual influence of the different phases. The presence of single‐phase unevenly distributed users, leads to unbalances in the power flow on the three phases. This issue is emphasised considering the presence of local single‐phase generators. This study presents a generalised method for transformers modelling in any multi‐conductor grid representation in order to allow the analysis on unbalanced networks such as low‐voltage distribution systems. The method, based on an incidence matrix approach, is proposed to represent any network object involving mutual connections among the phases, once the impedances for each single‐phase equivalent circuit are known. Some application examples validate the approach and illustrate how to numerically realise the model.

Keywords

• generalised transformer modelling
• power flow calculation
• multiphase unbalanced networks
• power flow
• local single‐phase generators
• transformers modelling