Method for sensing a fault in a power system based on travelling wave currents

摘要

A fault sensing system for a power system including a protected unit is disclosed. The fault sensing system is adapted to sense a fault in the protected unit. The fault sensing system includes at least one current sensing unit adapted to sense at least one first current in a first position in the protected unit and at least one second current in the second position in the protected unit and at least one voltage sensing unit adapted to sense at least one first voltage in the first position and at least one second voltage in the second position, and at least one processing unit. The at least one processing unit is adapted to model any distortion, attenuation and/or delay of the waveform of a wave due to propagation of the wave in the protected unit by means of a propagation function, determine at least one first travelling wave current in the first position based on the at least one first current and the at least one first voltage, determine at least one second travelling wave current in the second position based on the at least one second current and the at least one second voltage, estimate at least one of the at least one first travelling wave current and the at least one second travelling wave current by applying the propagation function to the at least one second travelling wave current or to the at least one first travelling wave current, respectively, on a condition that the at least one first travelling wave current is estimated, compare the estimated at least one first travelling wave current with the determined at least one first travelling wave current, on a condition that the at least one second travelling wave current is estimated, compare the estimated at least one second travelling wave current with the determined at least one second travelling wave current, and, based on the comparison or comparisons, determine whether there is a fault in the protected unit.