| 摘要 |
The present invention relates to a method for protecting a zone in a power system, which zone comprises a number of transmission lines connected to power sources and a number of transmission lines connected to a number of loads where the power sources and the loads are arranged outside the zone, wherein the method comprises the steps of: continuously measuring all the incoming currents (Iin) to the zone, continuously measuring all the outgoing currents (Iout) from the zone, and continuously calculating the differential current (Id) according to Id=Iin-Iout. The method is characterised in continuously integrating Iin, Iout and Id according to Formula (I), where T is the fundamental frequency cycle, whereby changes of the continuously integrated values I?IN?, IOUT and ID constitute indications of whether faults on the power system occur within or outside the zone. The present invention also relates to a device and computer program product for performing the method.
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