Sympathetic Interaction Phenomenon in Series-Connected Power Transformers
Herivelto de Souza Bronzeado1; Nelson Clodoaldo de Jesus2
1 Presidência da República; 2 GSI Engenharia consultoria LTDA
Resumo
In power systems with appreciable series impedance, such as those with long transmission lines, the transformers already connected to the supply system can experience unexpected saturation during the inrush transient of an incoming transformer. This saturation, which is established by the asymmetrical voltage drop across the system resistance produced by the inrush current, demands magnetising currents of high magnitude in the already connected transformers. This generates a transient interaction between the transformers, a "sympathetic interaction", which affects the magnitude and duration of the inrush current. Consequently, problems in the operation of the system, such as voltage dips, false operation of transformer protection and prolonged temporary harmonic overvoltages may occur. The sympathetic interaction between the transformers, mainly between those connected "in series", is analysed in the paper.
Palavras-chave: Transformer transient inrush; transformer saturation; sympathetic interaction; series-connected trasnsformers