Patent ID: 11971440
Assignee: UNIVERSITY OF MANITOBA
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H  Y | IPC G  H

Claim 0:
1. A method for identifying one or more faulted conductors when a fault event has occurred in a power transmission system in which at least two of the conductors transmit power, wherein the power transmission system is a high voltage direct current (HVDC) transmission system having two power-transmitting conductors and no return conductor, the power-transmitting conductors being operably connected between two sets of power converter stations so as to transmit the power along the power-transmitting conductors from a first one of the two sets of power converter stations to a second one of the two sets of power converter stations, the method comprising:
monitoring current signals which are representative of currents in the conductors at a generally common location within the power transmission system;
filtering the current signals to produce filtered current signals;
determining a maximum rate of change of each filtered current signal within a predetermined time interval after the fault event has commenced;
calculating a ratio of a pair of the maximum rates of change of the filtered current signals; and
comparing the ratio against a threshold value to identify the one or more faulted conductors, wherein the threshold value is a positive constant representative of a minimum ratio of a pair of the maximum rates of change of the filtered current signals based on a fault occurring at a maximum distance from the generally common location at which the current signals are monitored;
wherein monitoring the current signals comprises measuring the current in each one of the power-transmitting conductors at or generally in proximity to a common selected one of the first and second sets of power converter stations;
wherein the ratio of a pair of the maximum rates of change of the filtered current signals is formed by dividing the maximum rate of change of the filtered current signal of a first one of the power-transmitting conductors assuming a positive current direction through the first power-transmitting conductor so as to be assigned a positive value, by the maximum rate of change of the filtered current signal of a second one of the power-transmitting conductors assuming a negative current direction through the second power-transmitting conductor so as to be assigned a negative value, where the positive current direction through the first power-transmitting conductor is taken as flowing out of the selected set of power converter stations and the negative current direction through the second power-transmitting conductor is taken as flowing into the selected set of power converter stations; and
wherein comparing the ratio against a threshold value to identify the one or more faulted conductors comprises:
checking whether the ratio is greater than or equal to the threshold value or less than or equal to an inverse of the threshold value, and
if the ratio is greater than or equal to the threshold value then determining that the first conductor is the only faulted conductor, or
if the ratio is less than or equal to the inverse of the threshold value then determining that the second conductor is the only faulted conductor.