The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 21, 2006
Filed:
Jul. 11, 2001
Jianping Wang, Västeräs, SE;
Zoran Gajic, Västeräs, SE;
Mikael Goransson, Västeräs, SE;
ABB AB, Vasteras, SE;
Abstract
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 (I) to the zone, continuously measuring all the outgoing currents (I) from the zone, continuously calculating the differential current (I) according to I=I−I, continuously calculating q=I/I, continuously comparing q with set values and continuously comparing Iwith a set value Set1. The invention is characterised by setting I=I=Iat the instant when q changes and Iexceeds 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 Iin 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.