Research Of Principle And Measurement Of Anti-malfunction Of The Transformer Sympathetic Inrush

Differential protection has been a major protection of transformer in a long time. How to prevent the inrush causing malfunction in differential protection is a key and difficult problem. These years, there are instances of sympathetic inrush resulting in the malfunction of transformers'differential protection, the security and stability of power system is greatly affected. Considering the reasons of the malfunction of differential protection, the research for new algorithm of identifying the sympathetic inrush, is in highly demand. The major combustions of this dissertation are as follows:1. The simulation models of sympathetic inrush are developed. The principle and the reasons of the malfunction of differential protection are analyzed in the dissertation.2. The principle of sympathetic inrush in two transformers connected in wye-delta mode is analyzed. A new method of identifying the sympathetic inrush which is based on the time differential method is put forward.3. A new transformer protection method of identifying the winding parameter based on the square-root algorithm is put forward, this method could identify the internal,external fault,inrush (including sympathetic inrush ) correctly.