Abstract: A method of current differential protection performed in a control device is disclosed, wherein the control device has a first operate-restrain characteristic with a differential characteristic pick-up setting ID. The method includes: determining currents of all terminals of a protected object; determining a differential current based on the determined currents; determining direct current, DC, components in the respective determined currents; detecting a fault; and adjusting, for a detected external fault, the operate-restrain characteristics by setting an adjusted differential characteristic pick-up setting ID_adj to be equal to the sum of the differential characteristic pick-up setting ID and the determined DC components, providing an adapted operate-restrain characteristics. Corresponding control device, computer program and computer program product are also disclosed.

Abstract: A method of current differential protection performed in a control device is disclosed, wherein the control device has a first operate-restrain characteristic with a differential characteristic pick-up setting ID. The method includes: determining currents of all terminals of a protected object; determining a differential current based on the determined currents; determining direct current, DC, components in the respective determined currents; detecting a fault; and adjusting, for a detected external fault, the operate-restrain characteristics by setting an adjusted differential characteristic pick-up setting ID_adj to be equal to the sum of the differential characteristic pick-up setting ID and the determined DC components, providing an adapted operate-restrain characteristics. Corresponding control device, computer program and computer program product are also disclosed.

Abstract: The present invention discloses a method for detecting a fault and a current differential protection system thereof. The method for detecting fault includes calculating fault component currents, calculating an operate current and a restraint current of all terminals, and adjusting an operate level by adapting an operate-restraint characteristic according to a fault component. The method has very small operating area for external faults, which makes the method very reliable even for the case with serious CT saturation. A very big operating area for internal faults makes the method very sensitive for internal faults even for a heavy load and high resistance fault.

Abstract: The present invention discloses a method for detecting a fault and a current differential protection system thereof. The method for detecting fault includes calculating fault component currents, calculating an operate current and a restraint current of all terminals, and adjusting an operate level by adapting an operate-restraint characteristic according to a fault component. The method has very small operating area for external faults, which makes the method very reliable even for the case with serious CT saturation. A very big operating area for internal faults makes the method very sensitive for internal faults even for a heavy load and high resistance fault.

Abstract: A method for disconnecting a generator from a power system when the generator and the thereto connected power system are non-synchronized. The method includes the steps of: determining that there is a loss of synchronization between the generator and the power system, which loss of synchronization provides an amplitude variation of an electrical parameter associated with the generator. The method further includes determining when a minimum amplitude of the electrical parameter will occur, wherein when the occurrence of the minimum amplitude has been predicted, providing a command signal for disconnecting the generator from the power system, wherein the command signal is provided prior to the minimum amplitude of the electrical parameter is attained, and disconnecting the generator from the power system approximately when the determined minimum amplitude of the electrical parameter occurs. It is also presented a protection system for a generator in a power system.

Abstract: A method for disconnecting a generator from a power system when the generator and the thereto connected power system are non-synchronized. The method includes the steps of: determining that there is a loss of synchronization between the generator and the power system, which loss of synchronization provides an amplitude variation of an electrical parameter associated with the generator. The method further includes determining when a minimum amplitude of the electrical parameter will occur, wherein when the occurrence of the minimum amplitude has been predicted, providing a command signal for disconnecting the generator from the power system, wherein the command signal is provided prior to the minimum amplitude of the electrical parameter is attained, and disconnecting the generator from the power system approximately when the determined minimum amplitude of the electrical parameter occurs. It is also presented a protection system for a generator in a power system.

Abstract: A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e.

Abstract: A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e.