Research Of Constructing Algorithm Of Circulating Current In Y-delta Connected Transformer And New Protection Of Transformer

Transformer is one of major electric apparatuses in power system.It plays an important role in the transmission of power supply.Therefore,the research for new algorithm of transformer protection with high performance,such as fast,reliable and sensible capabilities, is in highly demand.For Y-delta connected transformer,the circulating current in delta winding are not easily measurable.The dissertation makes a deep analysis on its affect of transformer protection. Based on the research of circulating current,two ways of the indirect calculation of circulating current are proposed.One is based on the controlled switching,the other is according as the transformer model loop equation,the results show the circulating current of calculated can reflect the actual circulating current accurately.And besides,a way based on the difference of equivalent instantaneous inductance between inrush currents and internal fault for the discrimination between inrush and fault current is proposed.