Title: Waveform sine principle based transformer excitation flow recognition method
Application Number: 200610113761 Application Date: 2006.10.16
Publication Number: 1967958 Publication Date: 2007.05.23
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H02H7/045;H02H3/32;G01R19/00
Applicant(s) Name: Beijing Jiaotong University Address:
Inventor(s) Name: He Jinghan;Li Jingzheng;Ou Zaojun
Attorney & Agent: maoyan sheng
Abstract:
    The invention relates to a transformer excitation inrush current recognize method based on wave-shape sine theory, wherein it uses the sine function character of normal operation, short circuit, and external circuit short; the excitation inrush current contains non-periodical component, and the distant angle has no sine character; via comparing the sine degrees, it can judge inrush current and short circuit. The invention defines and calculates out the wave-length non-sine degree sigmaS (t); comparing the wave-length non-sine degree and non-sine preset value sigmaSZd, to judge the inrush current and short circuit current; when the transformer is idle and closes gate, there is inrush current, sigmaS (t) is higher than preset value sigmaSZd; opening judging condition, closing protecting; when the transformer has short circuits, sigmaS (t) is lower than sigmaSZd, it will open protection. The invention has accurate judge and phase-divert brake, with significant effect on CT saturation.
Time: 12