SYNCHRONIZATION METHOD FOR CURRENT DIFFERENTIAL PROTECTION

摘要

The present invention provides a synchronization method for current differential protection comprises the following steps: selecting a point on the transmission line protected by the current differential protection; measuring the current and the voltage of each of the terminals of said transmission line; calculating the compensating voltage at the selected point respectively according to the measured current and the voltage of the each terminal; detecting and calculating the synchronization error by comparing all the compensating voltages. The current and voltage of each of the terminals are measured before a fault or after a fault, and can be measured in vectors or sampling values. The current and voltage of each of the terminals are phase quantities or sequence quantities. The point can be selected from any points of transmission line; preferably the middle or the ends of the transmission line or the T connected point of the multi-terminal transmission lines. The synchronization method further comprises a step of distinguishing the calculated synchronization error caused by a serious line parameter change or an asymmetrical channel switching by calculating the changing speed of the phase angle difference or the wave shift of said compensating voltage.