Patent ID: 8183718

Claim:
A method for controlled reclosing of at least one line connected between two sub-systems of an electric power system that has been subjected to a disturbance and which line has been opened as a result of the disturbance, the at least one line having at least one circuit breaker connected thereto, the two sub-systems of the electric power system being connected by at least one branch element, the method comprising: determining an angular difference between voltage vectors on both sides of the at least one circuit breaker or at end points of the at least one branch element; calculating an adaptive comparison value based on an estimation of a future angular difference between the sides of the at least one circuit breaker or end points of the at least one branch element during stationary operation after reclosing the at least one line, wherein the comparison value is based on an expected state after reclosing or an operational state before the opening; comparing the determined angular difference with the adaptive comparison value; completing or blocking reclosing of the at least one line in dependence on a magnitude of a deviation of the determined angular difference from the adaptive comparison value; and regularly calculating and automatically updating the adaptive comparison value based on the angle between the voltage vectors at the two end points of the branch element after reclosing of a disconnected branch element so that an adaptive value is obtained.