Special Problems in Current Differential Protection Based on Bergeron Model

UHV long transmission line takes on distinct characteristics of distributed parameters, and it has great capacitive currents. Traditional phase segregated current differential protection is severely influenced by distributed capacitive current. In order to realize differential protection with high sensitivity and reliability for UHV transmission line, phase segregated current differential protection based on Bergeron model had been put forward. The time-domain Bergeron model is widely used for calculation during fault transient period. In theory, new principle can completely compensate capacitive current, but in practical application, consecutive sample values are necessary to realize calculation of Bergeron equation. Therefore, it´s necessary to estimate the voltage or current values at non-sampling points. The paper proposes that the cubic spline interpolation algorithm can be used for calculation of Bergeron equation. Theoretical analysis and simulation tests show that the proposed method is valid and precise.