Interaction of Traction Substations in Phase Shift Technique Based Traction Power Supply Network

Voltage unbalance in public utility caused by the single-phase AC traction network is a significant issue. Simple formula-based estimation and load flow-based calculation of unbalance are commonly used but they do not take into account the interaction between traction substations in phase shift technique-based traction power supply network. This paper presents a comparative analysis of different unbalance calculation methods: simple formula-based and load flow-based calculations with and without considering loads in other phases. The results show that unbalance calculated without considering interaction of traction substations overestimates the actual unbalance present. A detailed numerical analysis on voltage unbalance variation with load in other sections is also presented and it is emphasized that thorough analysis needs to be carried out for balancing load in different sections.