FAULT DIRECTION PARAMETER INDICATOR DEVICE USING ONLY CURRENT AND RELATED METHODS

摘要

A method of determining a fault direction parameter of a fault on an AC transmission line 10 of a power distribution system 1 relative to a measurement location 12 of the transmission line 10 is described. The method comprises: measuring by a measurement unit 20 a time- dependent AC current of the transmission line 10 at the measurement location 12, thereby obtaining time-domain current data 80 indicative of the measured current; the measurement unit 20 comprising a current sensor for measuring the current at the measurement location 12 of the transmission line 10 but no voltage sensor; transmitting the current data to a decision logic section 36; obtaining a fault time 81 of the fault on the AC transmission line 10; identifying a first time tl and a second time t2 by identifying a periodically re-occurring feature of the current data 80, such that the fault time 81 is between the first time tl and the second time t2, wherein the periodically re-occurring feature is selected from the group consisting of a zero-crossing, a maximum, a minimum, a highest gradient of the current data; extracting, from the current data 80, an offset indicative parameter 82; 86, 87 indicative of a time offset 8G of the current at the fault time 81 wherein the offset indicative parameter 82 is a time interval between the first time t1 and the second time t2; calculating an offset direction parameter by comparing the offset indicative parameter 82; 86, 87 to a non-offset indicative parameter 84; and establishing the fault direction parameter based on the calculated offset direction parameter.