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US 7,002,784 B2Granted
Current compensation method and device for power system protection
AssigneeABB AB
InventorsJianping Wang, Zoran Gajic, Mikael Goransson
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AssigneeABB AB
InventorsJianping Wang, Zoran Gajic, Mikael Goransson
Estimating the term…
The present invention relates to a method for current compensation of a protection system 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 and a number of current transformers (CT) arranged to the transmission lines, 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, continuously calculating the differential current (Id) according to Id=Iin−Iout, continuously calculating q=Iout/Iin, continuously comparing q with set values and continuously comparing Iout with a set value Set1. The invention is characterised by setting Iout=Iin=Icomp at the instant when q changes and Iout exceeds the value set1, which is an indication of the occurrence of a fault external to the protection zone due to saturation of the CT of the faulted outgoing transmission line, and using the value Icomp in the protection system in order to prevent tripping of the protection system. The present invention also relates to a device and a computer program product for performing the method.
A method for current compensation of a protection system for protecting a zone in a power system having a number of incoming transmission lines connected to power sources and a number of outgoing transmission lines connected to a number of loads where the power sources and the loads are arranged outside the zone and a number of current transformers (CT) responsively coupled to the transmission lines, comprises the steps of:
A device for current compensation of a protection system for protecting a zone in a power system, having a number of incoming transmission lines connected to power sources and a number of outgoing transmission lines connected to a number of loads where the power sources and the loads are arranged outside the zone and a number of current transformers coupled to the transmission lines, comprising means for continuously measuring all incoming currents (Iin) to the zone, means continuously measuring all outgoing currents (Iout) from the zone, means for continuously calculating a differential current (Id) according to
A computer program product comprising computer code means or software code portions for making a computer or processor perform the steps of:
Dependencies are inferred from the claim text.