Abstract: A method and an apparatus for fault detection in a mixed configuration power transmission line including a plurality of sections arranged between one end of the transmission line and the other end of the transmission line and including at least one overhead line section and at least one cable section are disclosed. Based on a comparison travelling wave voltage or current time derivatives at the one end and the other end of the power transmission line with selected threshold values, it is determined if there is a fault occurring in at least one cable section of the power transmission line. Embodiments utilize amplification of travelling wave voltages and/or currents which may occur at junctions between a cable section and an adjacent overhead line section in determining if the fault occurs in a cable section of the power transmission line.

Abstract: The invention concerns a method of fault location in HVDC (High Voltage Direct Current) transmission lines, especially in mixed lines, where part of the line is overhead line and part is a cable line. The fault location is based on estimation arrival times of travelling waves induced by fault in transmission line that are propagating along the line from faulted point to the measurement point, which is located at one end of the transmission line.

Abstract: A method and an apparatus for fault detection in a mixed configuration power transmission line including a plurality of sections arranged between one end of the transmission line and the other end of the transmission line and including at least one overhead line section and at least one cable section are disclosed. Based on a comparison travelling wave voltage or current time derivatives at the one end and the other end of the power transmission line with selected threshold values, it is determined if there is a fault occurring in at least one cable section of the power transmission line. Embodiments utilize amplification of travelling wave voltages and/or currents which may occur at junctions between a cable section and an adjacent overhead line section in determining if the fault occurs in a cable section of the power transmission line.

Abstract: The invention concerns a method of fault location in HVDC (High Voltage Direct Current) transmission lines, especially in mixed lines, where part of the line is overhead line and part is a cable line. The fault location is based on estimation arrival times of travelling waves induced by fault in transmission line that are propagating along the line from faulted point to the measurement point, which is located at one end of the transmission line.

Abstract: A method for protecting a synchronous machine (2) against damage caused by pole slipping in a power generating unit or a drive unit (1) in an electric power network is disclosed. The method measures signals of current and voltage of the synchronous machine (2) and assumed constant parameters to determine a disturbance (Trig_start). When a disturbance is detected, an indicator of pole slipping is determined, and the time of rotor operation with the occurrence of pole slipping is totalized. Next, if a threshold value allowed for the rotor operation with slipping proves to be valid, corresponding measures protecting the synchronous machine (2) against slipping are implemented. If the detection process is not fulfilled, the process of sudden disturbance and/or the process of accrued detection is conducted until the criterion of pole slipping occurrence is fulfilled for the generator mode or for the motor mode.

Abstract: The subject of the invention is a method for protecting a synchronous machine (2) against damage caused by pole slipping, applicable during the operation of the synchronous machine in a power generating unit or a drive unit (1) in an electric power network.