This paper describes a Bergeron model based current differential protection modified algorithm for half-wavelength transmission line. The algorithm uses three points as the reference points for the Bergeron model based current differential protection. Differential current amplitudes are calculated for three reference points

and then three current amplitudes are accumulated with the sum divided by two to obtain calculation results approximately equal to the actual short-circuit current at the fault point. This algorithm has solved the traditional Bergeron model based current differential protection issues that affect the position of the reference point. EMTP simulation shows that this algorithm can calculate the fault current fault point effectively and is suitable for application to half-wavelength transmission line.