Influence of distributed generation interface transformer and DG configurations on Temporary Overvoltage (TOV)

This paper presents a comprehensive analysis of the impact of Distributed Generator Interface Transformer (DGIT) configuration on Temporary Over Voltage (TOV) on the healthy phases in a distribution feeder during an unsymmetrical fault. Three common types of transformer configurations are investigated both analytically and using EMTDC/PSCAD. Subsequently, an in-depth study of the effectiveness of grounding transformer in reducing the TOVs for both rotating machine based DG and inverter based DG has been performed. All these studies have been performed on study systems with realistic system data. The results of studies presented in this paper are expected to be helpful for utilities in assessing the impact of integration of distributed generators in their system and avoiding scenarios of high TOVs.