Current differential protection using time-domain compensation of capacitive current

Abstract

A novel current differential protection using time-domain compensation of capacitive current is proposed. The capacitive current compensation is carried out in time domain using sampled data based on the differential equation of Π-equivalent circuit of the transmission line. The advantages and disadvantages of this time-domain compensation is analyzed and compared to phasor compensation method and Bergeron transmission line model method, and the phasor differential protections based on the three methods are simulated. The simulation shows that the proposed method can effectively get free of the difficulties with the other two methods. The proposed method enables phaselet algorithm with short data window to be applied to differential protection, thereby reducing the trip time to 5 ms, and enhancing the selectivity and sensitivity of protection. Simulations indicate that this time domain capacitive current compensation can be applied to existing protection devices that are currently operating with lower sampling frequency and communication rate. (6 pages)