Differential protection method, device and system for monitoring a line of an electrical energy supply network

Abstract

A differential protection method monitors a line of an electrical energy supply network. Current signals are generated at the ends of the line using inductive current transformers, which current signals are proportional to a current flowing at the respective end. For each end, current measurement values are formed from the respective current signal using measuring devices, which current measurement values indicate a profile of the current flowing at the respective end. For each end, a respective charge value is determined from the current measurement values. The charge values of all the ends are summed to form a charge sum, and a fault signal that indicates an internal fault on the line is generated when the charge sum exceeds a charge threshold value. To perform line differential protection in the case of current transformer saturation, when transformer saturation of a current transformer is present, an estimated charge value is ascertained.